Mississippi River flooding

Losses, 2024 dollars

$4.3 billion

Losses at the time

$3.0 billion

Deaths

7

The losses and deaths are NCEI’s, counting everything the disaster did. The episodes below are only what the Weather Service filed in its Storm Events record, which counts damage differently and often not at all, so the two never add up and are shown apart.

• Flooding in Washington, March 31, 20114 eventsHeavy rainfall on melting snowpack along the east slopes of the Washington Cascades caused flooding along numerous streams in western Kittitas and Yakima counties. Reported rainfall included 2.5 inches in Easton and .69 inches in Cle Elum.
• Debris Flows and Flood in Washington, March 31, 2011$10,000 · 3 eventsSeveral days of heavy rain and snow melt in the east slopes of the northern Cascades resulted in flooding and debris flows across the area. Three-day rainfall totals ranged from two to five inches.
• Flooding in South Dakota, April 1 to 30, 2011$6.5 million · 6 eventsMajor flooding of the James River, other streams, lakes, and general flooding, which began with a rapid March snowmelt, continued through April. Water levels with the more general areal flooding were at the highest at the start of April.
• Flooding in South Dakota, April 1 to 30, 2011$800,000 · 17 eventsSnowmelt flooding in March continued across much of central and northeast South Dakota as the rest of the snowpack melted into early April. Many roads along with countless acres of crop and pastureland remained flooded.
• Flooding in South Dakota, April 1 to 30, 2011$1.2 million · 3 eventsFlooding of lakes and lowlands in several counties in southeast South Dakota continued through April. The flooding included farmland and other lowlands, with some roads flooded and damaged.
• Flooding in South Dakota, April 1 to 30, 2011$1.0 million · 5 eventsMajor flooding of the Big Sioux River, other streams, lakes, and general flooding, which began with a rapid March snowmelt, continued through April.
• Flooding in Minnesota, April 1 to 30, 2011$600,000 · 8 eventsFlooding of lake, streams, and lowlands in several counties in southwest Minnesota continued through April. The flooding included farmland and other lowlands, with some roads flooded and damaged.
• Flooding in Iowa, April 1 to 30, 2011$20,000 · 3 eventsFlooding that began as snow melt continued into April across northern Iowa along the west fork of the Des Moines River. Flooding was persistent, but relatively minor and caused little additional damage.
• Flood in Arkansas, April 1 to 6, 2011$15,000 · 1 eventThe Cache River at Patterson remained above flood stage from late March into the first week of April.
• Flooding in South Dakota, April 1 to 30, 20118 eventsThe snowmelt river flooding from March continued throughout April across much of northeast and part of north central South Dakota. The additional snowmelt runoff kept many rivers and creeks across the area over flood stage.
• Heavy Rain in Arkansas, April 1 to 30, 20116 eventsWidespread drought conditions existed at the beginning of April. However, rain picked up considerably over most areas during the month. In what ended up being a complete turn-around in conditions, several reporting stations ended up with their wettest April ever recorded.
• Flooding in Iowa, April 1 to 30, 20115 eventsFlooding of lake, streams, and lowlands in a few counties in northwest Iowa continued through April. The flooding included farmland and other lowlands, with some roads flooded and damaged.
• Flooding in South Dakota, April 1 to 29, 20113 eventsMinor to moderate flooding of the Vermillion River and other lowlands, including farmland, continued through most of April. A few roads were flooded and some of the roads were damaged.
• Debris Flows and Flooding in Idaho, April 1 to 20, 2011$2.5 million · 12 eventsA stationary trough of low pressure off the Pacific Northwest Coast steered a deep fetch of subtropical moisture into the Idaho Panhandle which persisted from the end of March through April 7th bringing several rounds of heavy rain.
• Flash Flood and Flooding in Washington, April 1 to 3, 20116 eventsEnd of March heavy rainfall on melting snowpack along the east slopes of the Washington Cascades caused flooding along numerous streams in western Kittitas and Yakima counties. Reported rainfall included 2.5 inches in Easton and .69 inches in Cle Elum.
• Flooding in Wisconsin, April 3 to 29, 2011$75,000 · 2 eventsSnow that melted in late March, combined with rains in late March and early April, caused the Mississippi River to go out of its banks.
• Flooding in North Dakota, April 3 to 30, 20112 deaths · 8 eventsThe winter of 2010-2011 generally brought above normal amounts of snow to the area, but particularly so for the Devils Lake basin, the Sheyenne River basin, and the Wild Rice River basin.
• Flooding in Minnesota, April 3 to 30, 20111 death · 9 eventsThe winter of 2010-2011 generally brought above normal amounts of snow to the area, but particularly so for portions of the central and southern Red River Valley.
• Flood and Damaging Winds in Indiana, April 4, 2011$41,000 · 61 kt wind · 3 eventsA line of showers and thunderstorms pushed eastward from Illinois into central Indiana during the early morning hours of the 4th of April. These storms were strong enough to produce a couple wind damage reports from northwest portions of the forecast area.
• Flash Flood in Michigan, April 4, 2011$1.0 million · 1 eventThunderstorms produced one to three inches of rainfall over three to six hours. The heavy rain combined with melting snow to produce flash flooding of small creeks and streams from Hesperia in Oceana County east-northeast through central Mecosta County and into western Isabella…
• Flood and Hail in Ohio, April 4, 2011$49,000 · 50 kt wind · 7 eventsDuring the evening hours of April 3rd, an area of low pressure over Iowa moved northeast toward northern Michigan. A warm front extending east from the low across southern Ohio lifted north. By daybreak on the 4th, the warm front was located along the Lake Erie shoreline.
• Flash Flood and Hail in Missouri, April 4, 2011$22,000 · 1.75 in hail · 4 eventsA strong low pressure system tracked northeast from Western Kansas into the Great Lakes during the time period from April 2nd-April 4th, 2011. As a result, a trailing cold front moved through the Mid-South during the morning and early afternoon hours of April 4th.
• Flash Flood and Hail in Alabama, April 4, 2011$601,000 · 1.5 in hail · 66 eventsA strong cold front produced a squall line across the Ohio, Tennessee and lower Mississippi Valleys during the afternoon and evening hours of the 4th. Ahead of the front, windy conditions developed with wind gusts of 30 to 40 mph.
• Flash Flood and Hail in Alabama, April 4, 2011$291,000 · 1.75 in hail · 91 eventsA line of showers and thunderstorms moved across central Alabama on April 4th, out ahead of a strong cold front. This line of storms produced widespread damaging winds and large hail.
• Flooding in Pennsylvania, April 5, 2011$55,000 · 2 eventsRunoff from previous heavy rains casued Chartiers Creek and 10 Mile Creek to leave their banks and produce standing water on roadways in Washington county.
• Flooding in Montana, April 5 to 30, 20114 eventsExcessive rainfall coupled with the melting of record winter snows brought flooding to the area. The flooding continued into May.
• Flash Flood and Winter Storm in Hawaii, April 6 to 9, 201114 eventsAn upper low in the vicinity of the Hawaiian Islands generated heavy rain and thunderstorms over much of the Aloha State. The volcano summits on the Big Island received snow showers as well. No significant injuries or property damage were reported.
• Flood in Arkansas, April 8 to 14, 2011$25,000 · 1 eventAfter a brief period below flood stage, the Cache River at Patterson once again rose above flood stage.
• Flash Flooding and Flood in Indiana, April 9, 2011$30,000 · 1 in hail · 12 eventsScattered thunderstorms pushed eastward across central and southern Illinois into central Indiana during the morning hours of April the 9th.
• Flooding in Indiana, April 9 to 30, 2011$40,000 · 2 eventsThe White River began its upward trek in mid-April, cresting above major flooding levels late in the month. Another slightly higher crest occurred in early May. The April-May 2011 flood began to form in early April.
• Flash Flooding and Hail in West Virginia, April 9, 2011$495,000 · 1.75 in hail · 8 eventsA mesoscale convective complex moved southeast out of Indiana across eastern Kentucky and into southern West Virginia. With ample moisture, instability, and lift, new storms formed ahead of the initial complex.
• Flooding in North Dakota, April 10 to 30, 20119 eventsThe winter of 2010-2011 generally brought above normal amounts of snow to the area, but particularly so for the Devils Lake basin, the Sheyenne River basin, and the Wild Rice River basin.
• Flooding in Illinois, April 10 to 30, 2011$240,000 · 6 eventsThe Ohio River began its upward climb toward historic levels. The river rose above flood stage about mid-month. A series of heavy rainfall events gradually forced the river upward at an unsteady rate.
• Flooding in Vermont, April 11 to 14, 20111 death · $75,000 · 6 eventsLight to moderate rain associated with a warm front late on April 10 was preceded by several days of above freezing temperatures and melting snow. On April 11 a cluster of thunderstorms moved west to east across northern Vermont during the morning hours.
• Flooding in New York, April 11 to 12, 2011$30,000 · 3 eventsLight to moderate rain associated with a warm front late on April 10 was preceded by several days of above freezing temperatures and melting snow. On April 11 a cluster of thunderstorms moved west to east across northern New York during the early morning hours.
• Flash Flood and Damaging Winds in Tennessee, April 11, 2011$15,000 · 50 kt wind · 5 eventsA cold front moved through the Midsouth with a few rounds of thunderstorms. During the early morning hours storms developed in the warm and unstable air in advance of the front. These storms produced damaging winds.
• Flooding in Indiana, April 11 to 30, 2011$30,000 · 4 eventsThe Ohio River rose above flood stage about mid-month. A series of heavy rainfall events gradually forced the river upward at an unsteady rate. From Evansville downriver past the Wabash, the river continued rising past the end of the month.
• Flooding in New Hampshire, April 11 to 15, 20113 eventsMelting snow from several days of warm temperatures for caused northern portions of the Connecticut River to rise. Low pressure moving along a cold front then produced 1 to 2 inches of rain across the area which caused minor flooding of the river.
• Flooding in Indiana, April 12 to 30, 20113 eventsA cold front brought heavy rains to the area, causing river flooding over much of south central Indiana and central Kentucky. Additional heavy rains later in April kept the Ohio River at Tell City above flood stage through the end of the month.
• Flash Flooding and Flooding in Kentucky, April 12, 201126 eventsA slow moving low pressure system tracked across southeastern KY on April 12. Ample moisture from the Gulf of Mexico wrapped around this vertically stacked low pressure system into central Kentucky. A deformation band set up across this area.
• Flash Flooding and Flooding in Kentucky, April 12, 2011$12,000 · 8 eventsOn April 12th, a slow exiting low pressure system produced constant rainfall over the northern portion of the CWA as the system was slow to exit the area. The low pressure center eventually moved off to the north but not before 2 flash flood warnings needed to be issued.
• Flooding in Kentucky, April 12 to 20, 201111 eventsA cold front brought heavy rains to the area, causing river flooding over much of south central Indiana and central Kentucky. Additional heavy rains later in April kept the Ohio River at Tell City above flood stage through the end of the month.
• Flooding and Heavy Rain in Kentucky, April 12, 2011$8,000 · 6 eventsAn area of heavy rain caused flooding around the region.
• Flooding in Kentucky, April 12, 2011$80,000 · 3 eventsRain began Monday evening the 11th, around the north side of a strong mid level disturbance. The rain increased during the predawn hours on the 12th. Rain amounts of 1 to 1.5 inches were measured by dawn on the 12th.
• Flooding in Ohio, April 12, 2011$15,000 · 2 eventsRain began Monday evening the 11th, around the north side of a strong mid level disturbance. The rain increased during the predawn hours on the 12th. Rain amounts of 1 to 1.5 inches were measured by dawn on the 12th.
• Flooding and Heavy Rain in Ohio, April 12, 2011$9,000 · 8 eventsAn area of heavy rain caused flooding around the region.
• Flash Flooding in Virginia, April 12, 2011$220,000 · 3 eventsA strong upper level low pressure approaching from the west triggered shower and thunderstorm activity across the region. These storms were slow moving trained over the same areas producing very heavy rainfall.
• Flash Flooding in Virginia, April 12, 20118 eventsLow pressure both at the surface and the upper levels of the atmosphere passed through the region on the 12th. Showers and thunderstorms developed across the area.
• Flash Flooding in West Virginia, April 12, 20117 eventsLow pressure both at the surface and the upper levels of the atmosphere passed through the region on the 12th. Showers and thunderstorms developed across the area.
• Lakeshore Flood in Vermont, April 13 to 30, 20115 eventsRecord Flooding occurred along the shores of Lake Champlain from mid-April to mid-June.
• Flood in Massachusetts, April 13, 2011$40,000 · 1 eventA coastal storm brought heavy rain to much of southern New England. Areas of Cape Cod flooded as a result of two to six inches of rain.
• Flood in Iowa, April 13 to 22, 2011$250,000 · 1 eventWater from snow-melt in the upper Midwest moved south through the Mississippi River basin causing major flooding along the Mississippi River. The snowfall was well above normal for the 2010-11 winter in much of Minnesota and Wisconsin.
• Flood in Illinois, April 13 to 22, 2011$250,000 · 1 eventWater from snow-melt in the upper Midwest moved south through the Mississippi River basin causing major flooding along the Mississippi River. The snowfall was well above normal for the 2010-11 winter in much of Minnesota and Wisconsin.
• Flooding in Kentucky, April 13 to 30, 2011$50,000 · 7 eventsThe Ohio River began its upward climb, approaching historic levels in places downriver from the Smithland area. The river rose above flood stage about mid-month. A series of heavy rainfall events gradually forced the river upward at an unsteady rate.
• Flooding in Virginia, April 14, 201123 eventsStrong southerly flow at the low levels brought northward a highly moist atmosphere from the Gulf of Mexico into the Mid-Atlantic. Widespread moderate to heavy rain developed in advance of a slow moving cold front on the morning of the 14th, causing flooding.
• Debris Flow in California, April 14, 2011$100,000 · 1 eventStorms from March provided the necessary moisture to cause a hillside to fail producing a debris flow weeks later.
• Flash Flood and Hail in Mississippi, April 15, 20111 in hail · 7 eventsA Strong area of low pressure in Oklahoma intensified and moved into the Mid Mississippi Valley on April 15, 2011.
• Flash Flooding and Damaging Winds in Alabama, April 15, 2011$10,000 · 52 kt wind · 9 eventsNorth Alabama averted most of the severe weather associated with a large severe weather outbreak across the deep South.
• Flood in Arkansas, April 16 to 30, 2011$60,000 · 1 eventHeavy rainfall from spring thunderstorms caused the Cache River at Patterson to rise back above flood stage during the middle of the month. Additional very heavy rainfall kept the river above flood stage through the rest of the the month, and into the month of May.
• Flash Flooding in Kentucky, April 16, 20114 eventsOn April 16th, showers and thunderstorms moved north into Bell, Harlan, and Pike counties. The storms trained over the same areas, prompting the issuance of 2 flash flood warnings.
• Flash Flooding in West Virginia, April 16, 20111 death · $50,000 · 4 eventsShowers and thunderstorms moved north during the overnight hours, ahead of an approaching cold front.
• Flooding in Ohio, April 16, 2011$15,000 · 2 eventsShowers and thunderstorms with heavy rain caused some small streams and creeks to be bankfull or overflow in the afternoon.
• Flash Flooding and Flooding in Virginia, April 16 to 17, 20112 deaths · $30,000 · 15 eventsA strong and closed low pressure system over the Ohio Valley remained nearly stationary through the 16th, bringing copious moisture northward up the eastern seaboard.
• Flash Flood and Flooding in West Virginia, April 16, 201110 eventsA strong and closed low pressure system over the Ohio Valley remained nearly stationary through the 16th, bringing copious moisture northward up the eastern seaboard.
• Coastal Flood in Maryland, April 16 to 17, 20113 eventsA strong pressure gradient between high pressure over the Atlantic Ocean and a cold front moving in from the Ohio Valley resulted in a strong onshore flow.
• Flooding in Iowa, April 16 to 30, 2011$1.5 million · 6 eventsWater from snow-melt in the upper Midwest moved south through the Mississippi River basin causing major flooding along the Mississippi River. The snowfall was well above normal for the 2010-11 winter in much of Minnesota and Wisconsin.
• Flooding in Illinois, April 16 to 30, 2011$1.3 million · 5 eventsWater from snow-melt in the upper Midwest moved south through the Mississippi River basin causing major flooding along the Mississippi River. The snowfall was well above normal for the 2010-11 winter in much of Minnesota and Wisconsin.
• Flash Flooding and Damaging Winds in Pennsylvania, April 16 to 17, 2011$25,000 · 50 kt wind · 12 eventsA dynamic area of low pressure and trailing frontal zone moved across southeastern Pennsylvania during the late afternoon and evening, producing intense lines of heavy showers and thunderstorms.
• Coastal Flood in New York, April 16, 20115 eventsA tight pressure gradient, between strong low pressure tracking from the Mid-Mississippi River Valley to the Great Lakes and stubborn high pressure over the Canadian Maritimes, created a 24-30 hour period of strong east to northeast winds across the region April 16 into the…
• Coastal Flood in New Jersey, April 16, 20111 injured · $1.0 million · 5 eventsThe strong southeast onshore flow on the 16th combined with the already high astronomical tides associated with the full moon to produce minor to moderate tidal flooding along the New Jersey oceanic coast and moderate to severe flooding in Delaware Bay in Cape May and Cumberland…
• Flash Flood and High Wind in Pennsylvania, April 16 to 17, 2011$185,000 · 54 kt wind · 5 eventsA low pressure system moved northeast from Illinois to the Great Lakes region during the day. With high pressure to the east over New England, a tightening pressure gradient brought an increase in winds as the low approached.
• Flooding in Maryland, April 16 to 17, 20114 eventsA strong and closed low pressure system over the Ohio Valley remained nearly stationary through the 16th, bringing copious moisture northward up the eastern seaboard.
• Flooding in Pennsylvania, April 16 to 17, 20114 eventsA dynamic area of low pressure and trailing frontal zone moved across southeastern Pennsylvania during the late afternoon and evening. Deep moisture and very strong wind fields ahead of the frontal system produced torrential rains with 3-4 inches of rain observed.
• Flooding in Pennsylvania, April 16 to 17, 20116 eventsHeavy rain caused poor drainage flooding in Eastern Pennsylvania and mainly minor to moderate creek and river flooding in Berks County and Southeastern Pennsylvania.
• Coastal Flood in New Jersey, April 16 to 17, 20111 death · $1.5 million · 4 eventsThe strong southeast wind up the Delaware Bay and River combined with the already high astronomical tides associated with the full moon and fresh water runoff from heavy rain to produce severe tidal flooding along the Delaware River and tidal sections of its tributaries during…
• Coastal Flood in Delaware, April 16 to 17, 2011$100,000 · 1 eventThe strong southeast wind up the Delaware Bay and River combined with the already high astronomical tides associated with the full moon and fresh water runoff from heavy rain to produce severe tidal flooding along the Delaware River and tidal sections of its tributaries during…
• Flooding in New Jersey, April 16 to 22, 2011$250,000 · 7 eventsHeavy rain caused poor drainage flooding in New Jersey and stream and river flooding mainly in west central and northern New Jersey. Major flooding occurred again in sections of the Passaic River Basin.
• Flooding in New Jersey, April 16 to 17, 20114 eventsAs an area of low pressure tracked from the Great Lakes into Southeast Canada, a triple point low pressure system developed in the Ohio Valley. This storm system brought flooding rains to portions of Northeast New Jersey as it tracked north and west of the local area.
• Coastal Flood in Pennsylvania, April 16 to 17, 2011$250,000 · 3 eventsThe strong southeast wind up the Delaware Bay and River combined with the already high astronomical tides associated with the full moon and fresh water runoff from heavy rain to produce severe tidal flooding along the Delaware River and tidal sections of its tributaries during…
• Coastal Flood and High Wind in Maine, April 17, 201152 kt wind · 6 eventsStrong south to southeast winds developed between high pressure east of the maritimes and deep low pressure approaching from the southwest. The strong winds snapped branches and toppled trees which brought down powerlines contributing to numerous power outages.
• Flooding in Maine, April 17 to 18, 20113 eventsLow pressure developed in southern New England and moved northeast along the coast of Maine. Precipitation ranged from around 1 inch or less in the mountains to 2 or more inches along the coast. The runoff was enhanced by melting snow. Minor flooding occurred on area rivers.
• Flooding in Nebraska, April 17 to 30, 2011$20,000 · 4 eventsSeveral periods of moderate to heavy rain in eastern Nebraska and southwest Iowa combined with snow melt runoff in the upper Missouri basin brought increased flows along the Missouri River downstream of Omaha.
• Debris Flow in Wyoming, April 18, 2011$237,000 · 1 eventA rockslide on US Highway 14A east of Lovell in the Bighorn Mountains deposited at least 7,500 cubic yards of rock on the roadway. The slide occurred near milepost 73.4 and was witnessed and recorded by at least one person.
• Flooding in Utah, April 18 to 20, 2011$80,000 · 6 eventsThe combination of warmer temperatures and heavy rainfall caused flooding across many creeks and rivers across northern Utah. A few of the most impacted waterways included the Blacksmith Fork River, the Weber River, and Chalk Creek.
• Flash Flooding and Hail in Kentucky, April 19, 2011$3,000 · 1 in hail · 6 eventsAn area of storms moved through during the morning hours of April 19th. Hail, damaging winds, and flooding occurred with these storms.
• Flash Flood and Flooding in Ohio, April 19, 2011$23,000 · 0.88 in hail · 14 eventsAn area of storms moved through during the morning hours of April 19th bringing hail to the region.
• Flash Flood and Flood in Indiana, April 19, 2011$23,000 · 3 eventsShowers and thunderstorms moving over the area caused flash flooding in some locations.
• Flooding and Hail in West Virginia, April 19, 2011$100,000 · 0.88 in hail · 7 eventsOn Tuesday the 19th, a strong east to west front stretched from north central West Virginia on across extreme southern Ohio near the Ohio River.
• Flash Flood and Hail in Indiana, April 19, 2011$2,000 · 1.75 in hail · 8 eventsScattered showers and thunderstorms pushed east out of central Illinois into central Indiana during the late morning and early afternoon hours of the 19th of April.
• Flooding in Missouri, April 19 to 30, 2011$150,000 · 5 eventsThe Mississippi River began its upward trend toward historic flooding. The river rose above flood stage late in the month. A series of heavy rainfall events gradually forced the river upward at an unsteady rate. The river continued rising past the end of the month.
• Flooding and Hail in Ohio, April 19 to 21, 2011$242,000 · 61 kt wind · 8 eventsOn Tuesday the 19th, a strong east to west front stretched from north central West Virginia on across extreme southern Ohio near the Ohio River. Rounds of showers and thunderstorms moved into southeast Ohio around 0200E and continued into the late afternoon.
• Flooding in Ohio, April 19, 2011$65,000 · 9 eventsShowers and thunderstorms moving repeatedly along a stalled frontal boundary produced flooding of streams and creeks across parts of eastern Ohio, northern West Virginia, and Garrett county Maryland.
• Flooding in Kentucky, April 19 to 30, 20113 eventsThe Mississippi River began its upward trend toward historic flooding. The river rose above flood stage late in the month. A series of heavy rainfall events gradually forced the river upward at an unsteady rate. The river continued rising past the end of the month.
• Flood and Hail in Illinois, April 19, 20111 in hail · 10 eventsStrong thunderstorms with heavy rain and hail developed across Northern and Central Illinois during the evening of April 19th. Numerous reports of mostly sub-severe hail were received.
• Flooding in West Virginia, April 19, 2011$20,000 · 3 eventsShowers and thunderstorms moving repeatedly along a stalled frontal boundary produced flooding of streams and creeks across parts of eastern Ohio, northern West Virginia, and Garrett county Maryland.
• Flood in Maryland, April 19, 2011$25,000 · 1 eventShowers and thunderstorms moving repeatedly along a stalled frontal boundary produced flooding of streams and creeks across parts of eastern Ohio, northern West Virginia, and Garrett county Maryland.
• Flooding in West Virginia, April 19, 20113 eventsA wave of low pressure rode along a stationary boundary over northern West Virginia, producing scattered showers and isolated thunderstorms.
• Flash Flooding and Hail in Arkansas, April 19 to 21, 2011$383,000 · 2.5 in hail · 123 eventsA cold front approached Arkansas on the 19th. Thunderstorms developed in the warm, moist air out ahead of the front. From the evening of the 19th into the morning of the 20th, a line of storms formed and pushed across Arkansas.
• Flooding in Iowa, April 19 to 25, 2011$10,000 · 3 eventsWater levels along the west fork of the Des Moines River remained high though the month. Minor flooding also took place on the upper reaches of the east fork of the Des Moines River.
• Flash Flood and Hail in Arkansas, April 19 to 20, 20111.75 in hail · 19 eventsA strong area of low pressure moved from the Southern Plains into the Middle Mississippi Valley from April 19th into April 20th.
• Flash Flooding and Hail in Mississippi, April 19 to 20, 20111 injured · 1.75 in hail · 40 eventsA strong area of low pressure moved from the Southern Plains into the Middle Mississippi Valley from April 19th into April 20th.
• Flash Flooding and Hail in Alabama, April 20 to 21, 2011$493,000 · 1 in hail · 47 eventsA slow moving cold front caused two rounds of severe thunderstorms across Central Alabama, the first round in the morning hours of April 20, and the second round lasting from the evening of April 20 to the early morning of April 21.
• Flash Flooding and Hail in Arkansas, April 20 to 21, 20111.75 in hail · 17 eventsThe cold front, responsible for producing widespread severe weather across southern and southwest Arkansas during the evening of the 19th and early morning hour of the 20th, stalled out across the region during the afternoon and evening of the 20th.
• Flooding in Illinois, April 21 to 30, 2011$50,000 · 3 eventsThe Mississippi River rose above flood stage late in the month. A series of heavy rainfall events gradually forced the river upward at an unsteady rate. The river continued rising past the end of the month. Impacts of the May crest will be included in the May report.
• Flash Flood and Hail in Missouri, April 21, 20111.75 in hail · 3 eventsA cluster of strong to severe thunderstorms moved across southwest Missouri producing isolated large hail. This was in response to an upper level disturbance moving across the Ozarks.
• Flooding in Indiana, April 22 to 30, 2011$40,000 · 2 eventsThe Wabash River began its upward trek toward record high levels. The river crested at a record crest in early May at Mount Carmel. Details on the impact of the record crest will be included in the May report. The April-May 2011 flood began to form in early April.
• Flash Flood and Hail in Illinois, April 22, 20111.5 in hail · 8 eventsElevated convection fired up over the region on nose of strong low level jet. Numerous reports of large hail and isolated flash flooding were reported with these storms.
• Flash Flooding and Hail in Illinois, April 22 to 23, 20112 injured · $147,000 · 1.75 in hail · 17 eventsAn upper-level disturbance interacting with a frontal boundary brought periods of showers and thunderstorms to central and southeast Illinois on April 22nd.
• Flooding in Illinois, April 22 to 30, 2011$20,000 · 2 eventsThe Wabash River began its upward trek toward record high levels. The river crested at a record crest in early May at Mount Carmel. Details on the impact of the record crest will be included in the May report. The April-May 2011 flood began to form in early April.
• Flooding in Kentucky, April 22 to 30, 20119 eventsA squall line on April 23 caused flooding on the main stem of the Ohio River, along with another round of flooding on some tributaries of the Ohio. Many area rivers would remain in flood through the end of the month, with flooding continuing into May.
• Flash Flood and Hail in Illinois, April 22 to 23, 201166 kt wind · 4 eventsBands and clusters of strong to severe thunderstorms produced isolated reports of damaging winds. A fast-moving upper level trough tracked east-northeastward from the central Plains into the upper Midwest.
• Flash Flooding and Flooding in Missouri, April 22 to 26, 20112 deaths · $33 million · 143 eventsMultiple rounds of thunderstorms produced very heavy rainfall across the Ozarks over the course of a week. A persistent trough over the central plains brought multiple upper level storm systems over the region which produced intense thunderstorms with very heavy rainfall.
• Flooding and Hail in Ohio, April 22 to 25, 2011$277,000 · 50 kt wind · 11 eventsSeveral more rounds of showers and thunderstorms moved through southeast Ohio from Friday the 22nd into Sunday the 24th. This time the heaviest rains were a bit further south. The counties of Gallia and Lawrence were hit the hardest.
• Flash Flooding and Hail in Ohio, April 22 to 23, 2011$17,000 · 1.75 in hail · 10 eventsA complex of showers and thunderstorms moved through the area during the early morning hours.
• Flash Flooding and Flooding in Indiana, April 23, 20111 in hail · 14 eventsMultiple waves of showers and thunderstorms tracked along a boundary that was stalled out approximately along the Ohio River on April 23. These thunderstorms brought a mix of severe weather and heavy rain to the region.
• Flash Flooding in Indiana, April 23, 2011$22,000 · 3 eventsA complex of showers and thunderstorms moved through during the morning hours. This heavy rainfall caused some flooding across the area.
• Flood and Damaging Winds in Kentucky, April 23, 2011$57,000 · 50 kt wind · 7 eventsSeveral rounds of showers and thunderstorms moved through southern Ohio from Friday the 22nd into Sunday the 24th. The heaviest rains brushed Greenup County in northeast Kentucky.
• Flash Flooding and Hail in Missouri, April 23 to 26, 20111.5 in hail · 9 eventsA stationary front remained anchored over northern Arkansas to the Ohio Valley for several days. There were some isolated large hail reports as well as several rounds of very heavy rainfall which caused flash flooding through the 26th of April.
• Flash Flooding in Indiana, April 23, 2011$20,000 · 2 eventsBands of thunderstorms developed along a surface cold front extending from northern Arkansas northeastward along the Ohio River. Relatively strong diurnal heating occurred south of the front, where mixed-layer cape values increased to around 1500 j/kg.
• Flash Flooding and Damaging Wind in Ohio, April 23, 2011$20,000 · 50 kt wind · 4 eventsA line of storms moved through during the afternoon hours of April 23rd. Damaging thunderstorm winds, tornadoes, and flash flooding occurred with this event.
• Flooding in Indiana, April 23 to 29, 20113 eventsThe main stem of the Ohio River had been in flood for much of late April. A squall line on April 23 caused new flooding on some of the flashier streams in south central Indiana.
• Flash Flooding and Hail in Illinois, April 23 to 26, 20110.88 in hail · 5 eventsA stationary front remained anchored over northern Arkansas to the Ohio Valley for several days. There were some isolated large hail reports as well as several rounds of very heavy rainfall which caused flash flooding through the 26th of April.
• Flooding in Arkansas, April 23 to 30, 2011$3.4 million · 20 eventsSeveral rounds of very heavy rainfall during the latter half of April caused many rivers across Arkansas to rise above flood stage. Rainfall amounts of 5 inches to well over 10 inches were seen, with much of that rain falling in a period of less than a week.
• Flash Flooding and Flooding in Kentucky, April 24, 20111.75 in hail · 19 eventsMultiple episodes of severe weather affected the region on April 24. During the morning storms moved in from the south producing a couple of damaging wind gusts. Later in the afternoon the atmosphere became unstable once again with some dry air intruding at the mid levels.
• Flash Flood and Flooding in Missouri, April 24 to 30, 2011$4.8 million · 6 eventsThe Current, Black, and St. Francis Rivers rose above flood stage late in the month. A series of heavy rainfall events gradually forced the rivers upward at an unsteady rate. Another round of heavy rain in early May sent some of the rivers to record high flood crests.
• Flooding in Missouri, April 24 to 30, 2011$1.3 million · 11 eventsWidespread heavy rainfall from 13 to 18 inches with locally higher amounts occurred during the last week of April. At the Cape Girardeau airport, a rainfall total of 16.45 inches was measured from April 22-30.
• Flooding in Illinois, April 24 to 30, 2011$110,000 · 19 eventsWidespread heavy rainfall from 8 to 14 inches occurred during the last week of April. At the Carbondale airport, a rainfall total of 11.01 inches was measured from April 22-30. This excessive rainfall caused most creeks and streams to flood for an extended period of time.
• Flooding in Kentucky, April 24 to 30, 201122 eventsWidespread heavy rainfall from 8 to 14 inches occurred during the last week of April. At the Paducah airport, a total of 11.11 inches fell from April 22-30.
• Flash Flooding and Hail in Missouri, April 24 to 26, 2011$60,000 · 1.75 in hail · 7 eventsSeveral clusters of thunderstorms occurred along a nearly stationary surface front that extended from northern Arkansas northeast across the Lower Ohio Valley.
• Flooding in Indiana, April 24 to 30, 20116 eventsWidespread heavy rainfall from 6 to 9 inches with locally higher amounts occurred during the last week of April. At Evansville, a total of 7.31 inches fell from April 22 to April 30.
• Flash Flooding and Hail in Kentucky, April 24 to 25, 2011$130,000 · 1.25 in hail · 16 eventsSeveral clusters of thunderstorms occurred along a nearly stationary surface front that extended from northern Arkansas northeast across the Lower Ohio Valley.
• Flash Flooding and Hail in Arkansas, April 24 to 25, 2011$175,000 · 1.75 in hail · 18 eventsOn the afternoon of the 24th, a stalled frontal boundary extended through northwestern Arkansas and far southeastern Oklahoma.
• Flash Flood and Hail in Kansas, April 25, 20111 in hail · 3 eventsNumerous showers and thunderstorms from the early morning into the afternoon on the 25th affected portions of south-central and southeast Kansas, in response to a strong upper level disturbance approaching from the southwest.
• Flash Flooding and Hail in Oklahoma, April 25, 2011$15,000 · 1.25 in hail · 17 eventsPeriods of showers and thunderstorms resulted in widespread heavy rainfall on the 25th with a frontal boundary extending through eastern Oklahoma and an upper level disturbance approaching the region.
• Flash Flooding and Hail in Arkansas, April 25, 20115 deaths · $350,000 · 0.75 in hail · 12 eventsPeriods of showers and thunderstorms resulted in widespread heavy rainfall on the 25th with a frontal boundary extending through northwestern Arkansas and an upper level disturbance approaching the region.
• Flash Flooding in Kansas, April 25, 20114 eventsMultiple rounds of thunderstorms produced very heavy rainfall across southeast Kansas over the course of a week. A persistent trough over the central plains brought multiple upper level storm systems over the region which produced intense thunderstorms with very heavy rainfall.
• Flash Flood and Hail in Tennessee, April 25, 2011$140,000 · 1 in hail · 12 eventsA boundary across the area triggered thunderstorms in east Tennessee during the afternoon and evening hours. A few became severe producing large hail and damaging thunderstorm wind.
• Flood in Oklahoma, April 25 to 26, 2011$50,000 · 1 eventAn active weather pattern across the Southern Plains resulted in several episodes of locally heavy rainfall over much of northeastern Oklahoma. This heavy rainfall resulted in record flooding along the Baron Fork River near Eldon.
• Flash Flooding in Ohio, April 25, 2011$180,000 · 3 eventsA large area of rain and embedded thunderstorms moved from central into northern Ohio during the afternoon and early evening hours as warm front lifted north over Lake Erie.
• Flash Flooding and Damaging Wind in Illinois, April 25, 2011$250,000 · 51 kt wind · 4 eventsA surface low pressure center developed northeastward from south central Oklahoma to southwest Missouri. A gradual increase in the warm sector southerly low level jet occurred as the surface low deepened.
• Flash Flooding and Hail in Pennsylvania, April 25 to 27, 2011$3.2 million · 1.75 in hail · 24 eventsA slow moving warm front pushed northward across northeast Pennsylvania late in the afternoon on April 25th.
• Flash Flood and Hail in Indiana, April 26 to 27, 2011$12,000 · 1 in hail · 3 eventsA weakening line of thunderstorms pushed into southern portions of central Indiana from the southwest during the 26th of April. Only isolated severe reports across southern portions of the forecast area were received.
• Flooding in Iowa, April 26 to 30, 20113 eventsA large storm system moved through the central U.S. late on the 25th into early the 27th. Although the rainfall was not extremely heavy, it was significant for late April.
• Flash Flood and Hail in Pennsylvania, April 26 to 27, 2011$1.9 million · 2 in hail · 18 eventsSeveral bands of strong to severe thunderstorms developed along two north-south axes of low level confluence across central Pennsylvania into upstate New York.
• Flash Flooding and Hail in New York, April 26, 2011$2.3 million · 1 in hail · 4 eventsA line of showers and thunderstorms crossed the area during the evening hours. The thunderstorms were accompanied by strong winds, large hail and intense rains. The winds downed trees and wires on Whig hill and one inch hall fell in Scio.
• Flash Flood and Flooding in New York, April 26 to 27, 2011$4.5 million · 3 eventsSnowmelt from an above normal snowpack and daytime high temperatures in the 50s and 60s on the 25th and 26th, combined with rainfall of a half to one inch early on the 26th to set the stage for a significant flood event across the region.
• Flash Flooding and Flooding in Vermont, April 26 to 29, 2011$5.9 million · 10 eventsSnowmelt from an above normal snowpack and daytime high temperatures in the 50s and 60s on the 25th and 26th, combined with rainfall of a half to one inch early on the 26th to set the stage for a significant flood event across the region.
• Flooding in New Hampshire, April 26 to 27, 2011$85,000 · 4 eventsA stationary front located along the Canadian border resulted in 2 to 3 inches of rain during the evening of April 26. The heaviest rain fell between 8 pm and midnight.
• Flash Flooding and Flooding in Kentucky, April 27 to 28, 2011$69,000 · 1 in hail · 40 eventsThis event began in the early morning hours of April 27 as a squall line extending from Louisville south into Tennessee. Some of the the line was in bowing segments. The morning event resulted in 4 severe thunderstorm warnings and 2 tornado warnings.
• Flooding in New Hampshire, April 27 to 30, 20117 eventsA stationary front located along the Canadian border provided a focus for heavy rain to develop during the evening of April 26. Up to 3 inches of rain fell in far northern New Hampshire. This caused rivers and streams to rise to minor or moderate flood levels.
• Flash Flooding in Kentucky, April 27, 20113 eventsA 994 mb surface low pressure center over north central Arkansas moved northeast along a quasi-stationary front into extreme southern Illinois. Lines and clusters of thunderstorms developed coincident with the surface low and southeast of the low.
• Flash Flood and Hail in Illinois, April 27, 20111 in hail · 5 eventsA 994 mb surface low pressure center over north central Arkansas moved northeast along a quasi-stationary front into extreme southern Illinois. Lines and clusters of thunderstorms with embedded rotational signatures developed coincident with the surface low.
• Flooding in New York, April 27 to 30, 2011$10 million · 3 eventsHeavy rain and snowmelt combined to produce significant flooding in the northern Adirondacks. Rivers were running high due to melt from an above normal snowpack, then two to three inches of rain fell across the area on April 26 and 27.
• Debris Flow in Idaho, April 27, 2011$75,000 · 1 eventA wet spring resulted in saturated soils across northern Idaho. Recent heavy rainfall on the 25th and 26th of April was too much for a hillside along East Hayden Lake Road. Rainfall totals for the event ranged from three-quarters of an inch to an inch and a half across this area.
• Flash Flooding and Hail in Pennsylvania, April 27 to 28, 2011$178,000 · 1.25 in hail · 36 eventsA fast-moving upper level impulse and attendant surface low pressure system moved across the Great Lakes Region.
• Flooding in New York, April 27 to 30, 2011$1.4 million · 11 eventsAbove normal to record precipitation of 5 to 9 inches occurred in April across a large area of New York State. There was above normal snowpack across the higher elevations of the Adirondacks with snow depths at least a foot above normal.
• Flood in Michigan, April 27 to 28, 2011$25,000 · 1 eventSeveral days of significant rainfall resulted in localized flooding in northern Cheboygan County. Inverness Trail was washed out near Maynard Road. Numerous other secondary and gravel roads were washed out and closed. Water levels reached the sides of a few homes.
• Flood and Hail in West Virginia, April 27 to 28, 2011$15,000 · 1 in hail · 7 eventsWidespread severe weather impacted the area. A strong upper level trough approaching from the west provided strong winds aloft, and a weak upper level low pressure system moved across during the afternoon hours setting off scattered thunderstorms.
• Flash Flooding and Flooding in Virginia, April 28, 201110 eventsA strong cold front slowly passed through the region during the morning of the 28th A southerly flow ahead of the front caused deep moisture over the area. The cold front combined with the instability to trigger showers and thunderstorms with very heavy rainfall rates.
• Flash Flooding in West Virginia, April 28, 2011$5,000 · 6 eventsA strong cold front slowly passed through the region during the morning of the 28th A southerly flow ahead of the front caused deep moisture over the area. The cold front combined with the instability to trigger showers and thunderstorms with very heavy rainfall rates.
• Flash Flooding and Flood in New York, April 28 to 29, 2011$1.8 million · 3 eventsRainfall of one to 1.5 inches fell across the northern Adirondacks late on April 27 into the early morning hours of April 28.
• Flash Flooding and Flooding in Maryland, April 28, 20119 eventsA strong cold front slowly passed through the region during the morning of the 28th A southerly flow ahead of the front caused deep moisture over the area. The cold front combined with the instability to trigger showers and thunderstorms with very heavy rainfall rates.
• Flooding and Damaging Wind in Michigan, April 28, 2011$1,000 · 52 kt wind · 3 eventsAn isolated severe storm moved through Monroe.
• Flooding in Pennsylvania, April 28 to 30, 20114 eventsSeveral periods of very intense rain brought river flooding to the area. Moderate river flooding occurred along the Yellow Breeches Creek bordering York and Cumberland Counties.
• Flooding in New York, April 28 to 30, 20111 death · $1.4 million · 2 eventsAfter near record-setting spring rainfall, a warm front brought two to four inches of rain to the eastern Lake Ontario Region. The runoff resulted in flooding across the Black River basin, including the Black River and some of its major tributaries.
• Debris Flows in Puerto Rico, April 29, 20115 eventsAn upper level trough located west of Puerto Rico, combined with a strong upper level jet and moisture advected from the southeast, to produce numerous showers with thunderstorms across the region.
• Flooding in Arkansas, April 29 to 30, 2011$240,000 · 4 eventsVery heavy rainfall across northern and central Arkansas caused the White River to rise above flood stage late in the month. While the flooding was minor in the month of April, flooding persisted into the month of May where historic river levels were seen.
• Flash Flooding and Flood in Arkansas, April 30, 2011$47,000 · 1 in hail · 5 eventsA cold front pushed into Arkansas on the 30th and then became nearly stationary. Although there was isolated severe weather, the more significant event was heavy rain and flash flooding.
• Debris Flow in California, April 30, 2011$250,000 · 1 eventStorms from March provided the necessary moisture to cause a hillside to fail producing a debris flow weeks later.
• Lakeshore Flood in Vermont, May 1 to 31, 2011$9.8 million · 5 eventsRecord Flooding occurred along the shores of Lake Champlain from mid-April to mid-June.
• Lakeshore Flood in New York, May 1 to 31, 2011$5.0 million · 2 eventsRecord Flooding occurred along the shores of Lake Champlain from mid-April to mid-June.
• Flooding in Indiana, May 1 to 30, 2011$2.5 million · 10 eventsHeavy rainfall in March set the stage for major flooding when near-record rains fell in April and May. At Evansville, April was the second wettest April on record with 11.77 inches.
• Flash Flood and Flooding in Indiana, May 1 to 10, 2011$260,000 · 7 eventsWidespread flooding continued from April into May across southwest Indiana. Following excessive rain in April, a final dose of heavy rain came between April 30 and May 2.
• Flooding in New York, May 1 to 9, 20116 eventsIn April, the combination of several rounds of heavy rainfall from convection, rapid snowmelt due to the warm temperatures and above normal soil moisture led to increased runoff and rapid river rises.
• Flooding in Kentucky, May 1 to 10, 20115 eventsMany area rivers, including the main stem of the Ohio, went into flood in April and remained in flood through early May. Some additional heavy rains on May 2 and 3 slowed the fall or even delayed the crest on some of the streams.
• Flooding in New York, May 1 to 7, 20113 eventsHeavy rain and snowmelt combined to produce significant flooding in the northern Adirondacks. Rivers were running high due to melt from an above normal snowpack, then two to three inches of rain fell across the area on April 26 and 27.
• Flooding in Arkansas, May 1 to 31, 20114 deaths · $6.6 million · 14 eventsHeavy rains continued to occur across the Mid-Mississippi Valley into the Ohio Valley during the beginning part of May. In addition, spring snow melt across the Dakotas and Minnesota continued to create higher than normal river levels on the Mississippi River.
• Flooding in Arkansas, May 1 to 31, 20112 deaths · $250 million · 45 eventsAreal flooding was widespread in Arkansas, beginning early in May. The flooding was caused by large amounts of rain on April 30th, and May 1st and 2nd; high water flowing down from Missouri; and backwater flooding from rivers and large creeks and bayous.
• Flooding in Tennessee, May 1 to 31, 2011$2.0 billion · 5 eventsHeavy rains continued to occur across the Mid-Mississippi Valley into the Ohio Valley during the beginning part of May. In addition, spring snow melt across the Dakotas and Minnesota continued to create higher than normal river levels on the Mississippi River.
• Flooding in Mississippi, May 1 to 31, 2011$1.0 billion · 3 eventsHeavy rains continued to occur across the Mid-Mississippi Valley into the Ohio Valley during the beginning part of May. In addition, spring snow melt across the Dakotas and Minnesota continued to create higher than normal river levels on the Mississippi River.
• Flash Flooding and Flooding in Missouri, May 1 to 31, 2011$295 million · 13 eventsHeavy rainfall in March set the stage for major flooding when record-setting rains fell in April and May. At Cape Girardeau, 31.85 inches of rain fell between March and May.
• Flooding in North Dakota, May 1 to 31, 2011$110 million · 4 eventsThis was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains, not only in North Dakota but in Saskatchewan, Canada, as well.
• Flooding in Kentucky, May 1 to 31, 2011$32 million · 13 eventsHeavy rainfall in March set the stage for major flooding when record-setting rains fell in April and May. At Paducah, 15.91 inches of rain fell in April, which was 10.96 inches above normal.
• Flash Flood and Flooding in Kentucky, May 1 to 10, 2011$9.3 million · 23 eventsWidespread flooding continued from April into May across western Kentucky. Following excessive rain in April, a final dose of heavy rain came between April 30 and May 2.
• Flash Flood and Flooding in Illinois, May 1 to 31, 20111 injured · $7.3 million · 16 eventsHeavy rainfall in March set the stage for major flooding when record-setting rains fell in April and May. At Paducah, 15.91 inches of rain fell in April, which was 10.96 inches above normal.
• Flash Flood and Flooding in Missouri, May 1 to 10, 2011$7.9 million · 12 eventsWidespread flooding continued from April into May across southeast Missouri. Following excessive rain in April, a final dose of heavy rain came between April 30 and May 2. Numerous rounds of showers and thunderstorms produced additional average rainfall amounts of 4 to 6 inches.
• Flooding in Arkansas, May 1 to 31, 2011$2.3 million · 21 eventsWidespread heavy rainfall during late April and into the first part of May caused many rivers across the state to rise above flood stage. Many of the rivers rose above flood stage in late April, and the flooding persisted through much of May.
• Flooding in Illinois, May 1 to 10, 2011$1.5 million · 19 eventsWidespread flooding continued from April into May across southern Illinois. Following excessive rain in April, a final dose of heavy rain came between April 30 and May 2. Numerous rounds of showers and thunderstorms produced additional average rainfall amounts of 4 to 6 inches.
• Flooding in Missouri, May 1 to 31, 2011$750,000 · 2 eventsHeavy rains continued to occur across the Mid-Mississippi Valley into the Ohio Valley during the beginning part of May. In addition, spring snow melt across the Dakotas and Minnesota continued to create higher than normal river levels on the Mississippi River.
• Flood in Mississippi, May 1 to 31, 2011$250,000 · 1 eventSnow melt in the central and northern United States and heavy springtime rainfall in the Ohio Valley and Tennessee Valleys contributed to significant flooding along the lower Mississippi River. The magnitude of flooding was comparable to the floods of 1927, 1983, and 1993.
• Flooding in Nebraska, May 1 to 31, 2011$30,000 · 4 eventsSeveral episodes of heavy rain in eastern Nebraska and southwest Iowa combined with high flows upstream from snow melt and rain brought a prolonged period of flooding along the Missouri River, initially generally downstream of Plattsmouth, but by the end of the month it affected…
• Flooding in South Dakota, May 1 to 31, 20116 eventsModerate to major flooding on the James River continued through the month, with the river very slowly subsiding and no new flooding reported. Highest stages during the month were all on May 1st. Farmland and some roads near the river remained flooded.
• Heavy Rain in Arkansas, May 1 to 31, 20115 eventsSeveral reporting stations reported record rainfalls for the month of May.
• Flooding in South Dakota, May 1 to 31, 20114 eventsPrevious snowmelt and above normal May rainfall resulted in continued flooding on several rivers and creeks across northeast South Dakota throughout May.
• Flooding in North Dakota, May 1 to 17, 20113 eventsOverlanding flooding problems slowly abated by mid-May. It took longest to fall for areas just north of Fargo and from Oslo to Pembina.
• Flooding in Minnesota, May 1 to 17, 20113 eventsOverlanding flooding problems slowly abated by mid-May. It took longest to fall for areas just north of Fargo and from Oslo to Pembina.
• Flooding in South Dakota, May 1 to 31, 20113 eventsPrevious snowmelt along with above normal May rainfall kept parts of northeast South Dakota flooded throughout May. The counties mainly affected were Brown, Spink, and Edmunds. Crop and pastureland along with many roads remained flooded throughout the month.
• Flooding in North Dakota, May 1 to 13, 20113 eventsDevils Lake began the month at a level of about 1453.60 feet MSL and rose to a level of about 1454.25 feet MSL by the end of the month. Stump Lake also started at a level of about 1453.25 feet MSL and ended the month at about 1454.05 feet MSL.
• Flooding in Idaho, May 1 to 31, 2011$3,000 · 5 eventsExtensive snowfall melt combined with rain in May caused minor flooding in several counties.
• Flash Flooding and Hail in Oklahoma, May 1, 20111 in hail · 8 eventsA slow moving cold front moved through eastern Oklahoma on May 1st with widespread showers and thunderstorms occurring along and behind the front.
• Flash Flooding and Hail in Tennessee, May 1 to 2, 20111.75 in hail · 8 eventsA slow moving cold front moved into the Mid-South during the May 1st-May 3rd, 2011 time frame. Showers and thunderstorms developed along the front and trained across the same area. As a result, flash flooding occurred in areas mainly north of Interstate 40 in West Tennessee.
• Flash Flooding and Damaging Wind in Arkansas, May 1 to 2, 201150 kt wind · 4 eventsA slow moving cold front moved into the Mid-South during the May 1st-May 3rd, 2011 time frame. Showers and thunderstorms developed along the front and trained across the same area.
• Flash Flooding in Missouri, May 1 to 2, 20117 eventsA stubborn upper level trough over the central and southern Plains region along with a stalled out stationary front over the lower Mississippi Valley produced several rounds of moderate to heavy rainfall especially over the southern and eastern Ozarks.
• Flash Flood and Lightning Strike in Hawaii, May 1 to 3, 2011$50,000 · 14 eventsAn upper low in the area affected the Aloha State, bringing heavy rain and thunderstorms, and even small hail to parts of the Big Island of Hawaii and Maui. There were no reports of serious injuries. The costs of physical damages were not available.
• Flash Flooding and Flooding in Indiana, May 2, 201113 eventsStorms developed across southern Indiana just to the north of a frontal boundary stalled along the Ohio River. A LLJ impinging on the boundary and a shortwave over southern Illinois helped to enhance shower and thunderstorm activity.
• Flash Flood and Hail in Tennessee, May 2 to 3, 2011$36,000 · 1 in hail · 11 eventsSevere thunderstorms occurred across seven Middle Tennessee counties during the late afternoon through early evening hours on Monday, May 2nd. This resulted in funnel cloud, large hail, and thunderstorm wind damage reports, along with a flash flooding event.
• Flooding in Kentucky, May 3 to 7, 20116 eventsArea streams were running at high levels after flooding in April. A slow moving frontal boundary set off more heavy rains on May 2nd and 3rd. This caused renewed flooding on area streams.
• Flooding and Heavy Rain in Kentucky, May 3, 20116 eventsA nearly stationary front stretched from eastern KY through northern AL the morning of May 3. The area was also under the right entrance region of an upper level jet.
• Flooding in Kentucky, May 3, 2011$8,000 · 4 eventsAn area of showers and thunderstorms moved across the area during the morning hours. This heavy rain caused flooding across the region.
• Flash Flooding and Damaging Winds in Pennsylvania, May 3, 2011$8,000 · 50 kt wind · 6 eventsA broken line of severe thunderstorms formed ahead of a cold front during the late afternoon, and produced localized wind damage and heavy rainfall across portions of east-central Pennsylvania.
• Flooding in Mississippi, May 4 to 31, 20111 death · $11 million · 10 eventsThe flood of 2011 had its birth around the end of March when heavy rainfall of 2 to 5 inches fell across Arkansas, Southeast Missouri, and the Ohio River Valley.
• Flood in Arkansas, May 5 to 31, 2011$2.2 million · 1 eventThe flood of 2011 had its birth around the end of March when heavy rainfall of 2 to 5 inches fell across Arkansas, Southeast Missouri, and the Ohio River Valley.
• Flood in Louisiana, May 5 to 31, 2011$50,000 · 1 eventSnow melt in the central and northern United States and heavy springtime rainfall in the Ohio Valley and Tennessee Valleys contributed to significant flooding along the lower Mississippi River. The magnitude of flooding was comparable to the floods of 1927, 1983, and 1993.
• Flooding in Louisiana, May 6 to 31, 2011$25 million · 4 eventsThe flood of 2011 had its birth around the end of March when heavy rainfall of 2 to 5 inches fell across Arkansas, Southeast Missouri, and the Ohio River Valley.
• Flash Flooding and Heavy Rain in Hawaii, May 6 to 10, 20119 eventsAn upper trough remaining near the islands triggered heavy rain, thunderstorms, and flash flooding over much of the Aloha State. There were no serious injuries reported. Costs of any property damages were not available.
• Flood in Arkansas, May 6 to 9, 2011$15,000 · 1 eventThe Saline River at Rye rose above flood stage during the first week of May as a result of heavy rainfall and high water upstream.
• Flash Flooding and Hail in Indiana, May 7 to 8, 2011$17,000 · 1.5 in hail · 10 eventsA few thunderstorms pushed southeast out of east-central Illinois into central Indiana during the evening of May the 7th. One storm in particular, produced numerous large hail reports out of Vigo County. Flash flooding was also observed in Vigo County.
• Flood in Utah, May 8 to 9, 2011$50,000 · 1 eventSnowmelt and heavy rain caused flooding on the Blacksmith Fork River. This minor flooding caused several road closures around the towns of Logan and Millville.
• Flood in Alaska, May 8 to 12, 2011$1.5 million · 1 eventIce jam flooding along the Kuskokwim River at Crooked Creek and Red Devil caused significant damage. Ten homes were destroyed in Crooked Creek and 14 sustained damage. Four homes were damaged in Red Devil.
• Flash Flooding in North Dakota, May 9, 2011$11,000 · 2 eventsIn the early morning hours of the 9th, a cluster of elevated thundestorms moved from eastern South Dakota into western Minnesota. One storm dropped large hail near Norcross in Grant County (MN), which was the first severe thunderstorm event of the season.
• Flash Flood and Hail in Wyoming, May 9, 2011$163,000 · 1.5 in hail · 3 eventsA thunderstorm developed over Newcastle and remained over the city for over an hour. It produced ping-pong ball sized hail and heavy rain, which caused flash flooding.
• Flash Flooding and Flooding in South Dakota, May 9 to 10, 20118 eventsFlash flooding occurred over portions of northwestern South Dakota when three to four inches of rain fell in three hours.
• Flooding in Montana, May 10 to 17, 20116 eventsA significant spring storm impacted south central Montana May 8-11 as a moist and slow moving storm system impacted the region. Rain began to move into the region late Sunday, May 8th with the heaviest rainfall Monday into Tuesday.
• Flooding in Montana, May 10 to 14, 20114 eventsHeavy rains in Petroleum and Garfield counties swelled creeks and resulted in higher levels on the Musselshell River to above Flood Stage.
• Flooding in Montana, May 10 to 11, 20114 eventsHeavy rain fell in many areas of Valley, McCone, Garfield and Dawson counties where up to 2.5 inches fell, swelling creeks and rivers.
• Flash Flood and Hail in Virginia, May 10, 2011$15,000 · 2 in hail · 20 eventsStrong to severe storms developed along a warm front that stretched from Indiana southeast into the Carolinas.
• Flash Flooding and Hail in Kentucky, May 10 to 11, 2011$2.0 million · 1.75 in hail · 19 eventsRepetitive showers and thunderstorms, moved southeast through southeast Ohio and into portions of northeast Kentucky between 1500E and 1830E on Tuesday, the 10th. In northeast Kentucky, the heaviest rains fell in eastern Greenup County and Boyd County.
• Flash Flooding and Flooding in Ohio, May 10 to 12, 20111 death · $385,000 · 1.75 in hail · 60 eventsA very unstable airmass was in place south of a warm front in the area. This unstable airmass led to the development of widespread severe weather.
• Flash Flooding and Hail in Ohio, May 10 to 11, 2011$19 million · 1.75 in hail · 14 eventsRepetitive showers and thunderstorms, moved southeast through western Vinton County, Jackson County, and western and central portions of Lawrence County between 1500E and 1830E on Tuesday, the 10th. This convection was just northeast of the surface warm front.
• Flash Flooding and Hail in West Virginia, May 10 to 11, 2011$530,000 · 1 in hail · 9 eventsRepetitive showers and thunderstorms, moved southeast through southeast Ohio and into portions of northeast Kentucky, and western West Virginia between 1500E and 1900E on Tuesday, the 10th. This convection was just northeast of a warm front.
• Flooding in North Dakota, May 11 to 31, 2011$400,000 · 4 eventsThis was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains, not only in North Dakota but in Montana as well.
• Flash Flooding and Flood in Kentucky, May 11, 2011$106,000 · 1.25 in hail · 12 eventsA small cluster of strong to severe thunderstorms led to isolated instances of large hail, flash flooding, and tree damage in Johnson and Floyd counties during the overnight hours of May 11th.
• Flood and Hail in Oklahoma, May 11, 2011$16,000 · 61 kt wind · 21 eventsA powerful storm system moved through the inter-mountain west toward the southern Plains late on the 10th and into the 11th. Thunderstorms developed very early over eastern New Mexico/West Texas, as a lead disturbance rotated around main storm system.
• Flash Flooding and Hail in Michigan, May 11, 2011$194,000 · 1.5 in hail · 7 eventsA large area of showers and thunderstorms impacted Northern Michigan for much of the day on the 11th. The storms produced isolated severe weather and excessive rainfall, along with an area of high winds associated with a wake low trailing well behind the storms.
• Flash Flood and Hail in Texas, May 11, 20111.75 in hail · 13 eventsA shortwave and dryline combined to produce scattered severe thunderstorms. The main impacts with these thunderstorms were strong gusty winds and large hail.
• Flash Flooding and Hail in Texas, May 11 to 12, 2011$51,000 · 1.75 in hail · 55 eventsAn upper level area of low pressure moved out of the southern Rockies into the plains and combined with a dryline to produce severe thunderstorms on successive days. On May 11th the storms were mainly in the northeastern part of the forecast area.
• Flash Flood and Flood in Iowa, May 11, 2011$1,000 · 3 eventsTemperatures in the 80s and dew point temperatures in the mid/upper 60s from southeast Nebraska and southwest Iowa into eastern Kansas created moderately unstable conditions over the area as a large upper level low pressure system organized over Colorado.
• Flooding and Hail in Illinois, May 11, 2011$9,000 · 1.5 in hail · 25 eventsStrong to severe thunderstorms moved across many areas of northern Illinois during the afternoon and evening hours of May 11th.
• Flash Flood and Heavy Rain in Hawaii, May 11 to 14, 20116 eventsA surface trough west of the Garden Isle of Kauai caused inclement weather across Kauai and Oahu, triggering showers and thunderstorms. No serious injuries were reported. Costs of damages were not available.
• Flash Flooding and Flooding in Ohio, May 12 to 14, 2011$632,000 · 1.75 in hail · 35 eventsDuring the evening and nighttime hours of May 11th, an area of low pressure located over southern Wisconsin slowly progressed northeast over the upper Great Lakes. A frontal boundary extended southeast of the low, across portions of Indiana into southern Ohio.
• Flood and Hail in Ohio, May 12, 2011$20,000 · 1.75 in hail · 6 eventsSevere thunderstorms developed along a slow moving warm front that was positioned northwest to southeast across Ohio. Thunderstorms developed and rode along the front during both the morning and afternoon hours.
• Flash Flooding and Hail in West Virginia, May 12, 2011$35,000 · 1.75 in hail · 9 eventsPredawn convection was in northern and eastern Ohio, along a slowly moving warm front. The convection dropped southeast around the eastern side of the mid level ridge. Storms pulsed stronger, causing some large hail.
• Flash Flood and Hail in Texas, May 12, 2011$15,000 · 50 kt wind · 7 eventsA large complex of thunderstorms, that developed during the early morning hours south of Del Rio, moved across the entire South Texas region during the afternoon of May 12th. There were several reports of strong winds with these storms and a few reports of small hail.
• Flash Flood and Hail in Virginia, May 12, 2011$2,000 · 2 in hail · 18 eventsNorthwesterly flow aloft continued the pattern of storminess over the mountains as disturbances dropped southeast along the periphery of the upper ridge. Storms developed in the early afternoon and dropped mainly hail and heavy rain across several counties.
• Debris Flow and Flooding in Washington, May 12 to 17, 2011$46,000 · 8 eventsA wet spring season resulted in saturated soils across the Inland Northwest. Rivers, small streams, and creeks began to rise as warming temperatures on May 13th and 14th melted mountain snowpack across the east slopes of the northern Cascades and Northeast Mountains.
• Flash Flooding and Hail in Oklahoma, May 12, 2011$205,000 · 3 in hail · 25 eventsA cold front moved into and across the region during the afternoon and evening of the 12th. A warm, moist, and unstable air mass existed over eastern Oklahoma ahead of the front.
• Flash Flooding and Flood in Nebraska, May 12 to 13, 2011$4,000 · 1.75 in hail · 26 eventsSevere thunderstorms, some which produced heavy rain and flash flooding, tracked across eastern Nebraska for the second consecutive day. The storms were focused along two boundaries.
• Flooding and Hail in West Virginia, May 12, 2011$20,000 · 0.75 in hail · 3 eventsSevere thunderstorms developed along a slow moving warm front that was positioned northwest to southeast across Ohio. Thunderstorms developed and rode along the front during both the morning and afternoon hours.
• Flash Flooding and Hail in Arkansas, May 12, 2011$180,000 · 1.75 in hail · 9 eventsA cold front moved across northwestern Arkansas during the evening of the 12th. A warm, moist, and unstable air mass existed over the region ahead of the front.
• Flood in Pennsylvania, May 12, 2011$15,000 · 1 eventSevere thunderstorms developed along a slow moving warm front that was positioned northwest to southeast across Ohio. Thunderstorms developed and rode along the front during both the morning and afternoon hours.
• Flooding in Utah, May 13 to 18, 2011$550,000 · 2 eventsMore river flooding occurred across northern Utah in mid-May. The main rivers that were impacted were the Blacksmith Fork River and the South Fork of the Ogden River.
• Flash Flooding and Hail in Virginia, May 13, 2011$90,000 · 1 in hail · 18 eventsAn upper level storm system approaching from the west helped to trigger numerous showers and thunderstorms mainly over the Appalachians and Blue Ridge Mountains.
• Flooding and Hail in Pennsylvania, May 13 to 14, 2011$110,000 · 0.88 in hail · 16 eventsA low pressure system and its associated warm front were slowly progressing through the Ohio valley bringing numerous rounds of showers and thunderstorms.
• Flooding and Hail in Ohio, May 13, 2011$40,000 · 1 in hail · 5 eventsA low pressure system and its associated warm front were slowly progressing through the Ohio valley bringing numerous rounds of showers and thunderstorms.
• Flash Flood and Hail in North Carolina, May 13, 20111 in hail · 8 eventsAn upper level storm system approaching from the west helped to trigger numerous showers and thunderstorms mainly over the mountainous terrain of northwest North Carolina.
• Flash Flood and Hail in Mississippi, May 13, 20111.75 in hail · 6 eventsA mesoscale convective system moved through the Mid-South during the morning hours. This system generated outflow boundaries that when combined with surface heating and an upper level disturbance moving through the region produced scattered thunderstorms later in the day.
• Flash Flooding and Flood in New York, May 13, 2011$830,000 · 11 eventsLow pressure moved across the Great Lakes bringing moist, unstable air to the region. Showers and thunderstorms developed along lake breeze boundaries and persisted through the late afternoon and evening hours across the western southern tier and western Finger Lakes Region.
• Flash Flood and Hail in Michigan, May 13, 2011$100,000 · 1 in hail · 5 eventsA surface trough dropping south through Saginaw Bay interacted with thunderstorms coming up from the south, producing heavy rainfall around the I-69 corridor, specifically in Genessee county where flash flooding occured.
• Flash Flooding and Hail in Illinois, May 13 to 14, 20111 in hail · 4 eventsLow pressure moving across central Illinois triggered scattered strong thunderstorms during the evening of May 13th. A few of the storms produced large hail and locally heavy rainfall across Tazewell County and Christian County.
• Debris Flow and Flooding in Washington, May 14 to 23, 2011$4.3 million · 52 kt wind · 8 eventsAn upper level low pressure system moved over the Pacific Northwest. Moist and unstable conditions ahead of the low triggered widespread thunderstorms with heavy rainfall and isolated large hail. This combined with the abundant spring snow-pack and wet ground to cause flooding.
• Debris Flow in Wyoming, May 14 to 25, 2011$500,000 · 1 eventMud and debris began flowing onto US Highway 26/89 near milepost 127 in the Snake River Canyon on Saturday morning, May 14, as a result of rapid snowmelt in the area of Double Draw.
• Flash Flood and Debris Flow in Puerto Rico, May 14 to 18, 2011$365,000 · 53 kt wind · 9 eventsA broad trough associated with a persistent surface low north of the area and a wide northeast to southwest swath of moisture south of Puerto Rico moved very slowly east and created a highly unstable environment across the local area.
• Flash Flooding in Ohio, May 14 to 15, 20113 eventsA weak surface trough and low pressure system tracking along it allowed for thunderstorms to develop across portions of northwestern Ohio. Weak flow parallel to the trough allowed for redevelopment of thunderstorms, producing rainfall rates of one to two inches per hour.
• Flash Flooding and Flood in Ohio, May 14 to 15, 2011$65,000 · 12 eventsAn area of low pressure moved up from the Mississippi River Valley into Ohio. The storm system had adequate moisture from the Gulf of Mexico, which increased rainfall rates to over an inch and a half per hour.
• Flash Flood in West Virginia, May 14, 2011$50,000 · 1 eventA weak surface boundary rotated northeast through the area during the afternoon of the 14th. Short lines of thunderstorms developed in the afternoon heating, as clouds broke. Some repetitive showers caused narrow bands of heavy rain to fall.
• Heavy Rain in U.S. Virgin Islands, May 14 to 16, 20114 eventsMay 2011 ended as the fifth and eighth wettest May on record across St Thomas and St Croix respectively.The ASOS rainfall report from Cyril E. King Airport in St. Thomas was 8.04 inches for the month of May; 4.68 inches greater than the normal of 3.36 inches.
• Flash Flood and Flooding in Oregon, May 14 to 18, 2011$2.8 million · 1 in hail · 9 eventsAn upper level low pressure system moved over the Pacific Northwest. Moist and unstable conditions ahead of the low triggered widespread thunderstorms with heavy rainfall and isolated large hail.
• Flash Flooding and Flooding in Indiana, May 14 to 15, 2011$500,000 · 6 eventsA weak surface trough and low pressure system tracking along it allowed for thunderstorms to develop across portions of northeastern Indiana. Weak flow parallel to the trough and redevelopment of thunderstorms produced rainfall rates of one to two inches per hour.
• Flooding and Lightning Strike in Pennsylvania, May 14 to 16, 20111 injured · $25,000 · 6 eventsThunderstorms developed along a weak slow moving stationary front over Ohio. As was the case the days prior, storms were slow-moving causing flooding in northwestern Pennsylvania. Some wind damage was reported with the storms as they moved through the panhandle of West Virginia.
• Flooding in Idaho, May 15 to 17, 2011$25,000 · 2 eventsA wet spring season resulted in saturated soils across the Inland Northwest. Rivers, small streams, and creeks began to rise as temperatures warmed on May 13th and 14th as snowmelt infiltrated many watersheds across the Central Panhandle.
• Flood in Wyoming, May 15 to 19, 2011$200,000 · 1 eventLow elevation snowpack in the mountains bordering the west side of Star Valley melted rapidly as temperatures climbed into the 60s. The result was flooding along the Salt River and its tributaries.
• Coastal Flood in New York, May 16 to 17, 20113 eventsPersistent east winds over several days between broad low pressure over the Southeast United States and stubborn high pressure over Southeast Canada caused water to pile up along the coast.
• Flash Flooding in Virginia, May 16, 20113 eventsA nearly stationary area of low pressure over the Ohio Valley produced several days of intermittent showers and thunderstorms across the mid-Atlantic leading up to May 16th.
• Flash Flooding and Flooding in West Virginia, May 17 to 18, 20119 eventsA nearly stationary area of upper level low pressure system over the Ohio Valley provided plenty of lift to combine with an usually strong and moist southeasterly low-level flow to produce bands of moderate to heavy showers across the mid-Atlantic.
• Flash Flooding and Heavy Rain in Puerto Rico, May 17, 20113 eventsHeavy Rain occurred mainly across the eastern half of Puerto Rico.
• Flash Flooding and Flooding in Virginia, May 17 to 18, 201126 eventsA nearly stationary area of upper level low pressure system over the Ohio Valley provided plenty of lift to combine with an usually strong and moist southeasterly low-level flow to produce bands of moderate to heavy showers across the mid-Atlantic.
• Flash Flooding in Maryland, May 17 to 18, 20114 eventsA nearly stationary area of upper level low pressure system over the Ohio Valley provided plenty of lift to combine with an usually strong and moist southeasterly low-level flow to produce bands of moderate to heavy showers across the mid-Atlantic.
• Flooding in Montana, May 18 to 19, 201110 eventsAreas of heavy rain produced flooding on small streams in most of northeast Montana. The rainfall across the area during the month of May totaled 300 to 600 percent of normal.
• Flood and Hail in Pennsylvania, May 18, 2011$5,000 · 1 in hail · 3 eventsScattered severe thunderstorms developed in the afternoon in an area of instability and converegence as an upper level low meandered north and westward from the Appalachians.
• Flash Flooding in New Jersey, May 18, 20113 eventsA nearly stationary low pressure system over the Mid-Atlantic States produced heavy showers and thunderstorms that resulted in Flash Flooding across parts of Essex County.
• Flooding and Hail in Nebraska, May 19 to 20, 2011$795,000 · 1 in hail · 19 eventsFollowing a short stretch of dry days centered around mid-month, an abrupt transition to a very wet pattern arrived in parts of South Central Nebraska between the evening hours of Thursday the 19th and early morning hours of Friday the 20th.
• Flash Flooding and Flooding in Missouri, May 19, 201113 eventsA nocturnal thunderstorm complex moved across portions of west central and central Missouri. The storms were focused along a mid level boundary and produced as much as two to three inches of rain in some locations.
• Flooding in Montana, May 19 to 31, 2011$50,000 · 2 eventsHeavy rain and snowmelt caused several roads to be washed out as the Judith River and many small streams and creeks flooded. Flood declaration made for Judith Basin county on 5/23/11.
• Flooding in Montana, May 19 to 31, 2011$125,000 · 2 eventsHeavy rain and snowmelt resulted in flooding.
• Flash Flooding in New York, May 19, 2011$25,000 · 2 eventsA slow moving upper level low pressure system brought scattered showers and thunderstorms to upstate New York. Some of the storms brought heavy rainfall, and isolated storms produced flash flooding.
• Flash Flooding in Pennsylvania, May 19, 20114 eventsAn upper air disturbance helped trigger thunderstorms during the afternoon of the 19th. The thunderstorms were training and not fast movers. Coupled with the recent run of wet weather helped cause flash flooding in eastern parts of the Poconos and Lehigh Valley.
• Flood and Hail in Kansas, May 19 to 20, 2011$110,000 · 1.75 in hail · 33 eventsThunderstorms developed during the afternoon along a poorly defined dry line but had upper level support from a short wave trough.
• Flash Flood in Pennsylvania, May 19, 2011$15,000 · 1 eventA slow moving upper level low pressure system brought scattered showers and thunderstorms to northeast Pennsylvania. Some of the storms brought heavy rainfall, and isolated storms produced flash flooding.
• Flash Flooding in Pennsylvania, May 19, 20113 eventsHeavy rainfall from slow moving showers and thunderstorms produced localized flash flooding.
• Flash Flood in New York, May 19, 2011$150,000 · 1 eventA nearly stationary thunderstorm dropped about three inches of rain over Little Valley in Cattaraugus county in a little over an hour’s time. Many streets were closed some with over two feet of water over them virtually shutting down the village.
• Flash Flooding in New York, May 19 to 20, 20117 eventsA stacked low pressure system moved eastward from the Ohio Valley to Pennsylvania during the day Thursday, May 19th. Several upper level disturbances rotating around the low aided in the development of numerous showers and thunderstorms.
• Flooding and Hail in Nebraska, May 19 to 23, 2011$12,000 · 1 in hail · 9 eventsThunderstorms developed over eastern Nebraska during the evening of 5/19 ahead of a large upper level low pressure system over the Rocky Mountains and north of a warm front in Kansas.
• Flood and Hail in Kansas, May 19 to 20, 20111.25 in hail · 14 eventsAn upper level jet streak provided the dynamics to help produced thunderstorms during the afternoon and early evening. Some of the storms became severe.
• Flash Flooding in New York, May 20, 2011$80,000 · 6 eventsWidespread showers and a few thunderstorms developed across upstate New York as a slow moving upper level low pressure system rotated across the area. These showers and thunderstorms produced heavy rainfall, and resulted in flash flooding for parts of the area.
• Flooding and Heavy Rain in Nebraska, May 20 to 21, 2011$1.6 million · 5 eventsOnly 12-24 hours after significant rainfall drenched eastern sections of South Central Nebraska resulting in considerable lowland flooding and closure of several county roads, another round of heavy rain-producing storms flared up mainly between 2 PM and 9 PM CDT on Friday the…
• Flooding in South Dakota, May 20 to 31, 20116 eventsThe Missouri River, which had been near flood stage in many areas, began a significant rise near the end of the month in response to widespread upstream heavy rain which fell after unusually large upstream snowmelt.
• Flooding and Hail in Missouri, May 20, 20110.88 in hail · 11 eventsA broad area of rain moved over the Missouri Ozarks as moisture from the Gulf of Mexico and a subtropical fetch combined with an upper level disturbance. This produced heavy rainfall across portions of the Ozarks along with a few strong to marginally severe thunderstorms.
• Flash Flooding and Debris Flows in Puerto Rico, May 20, 201111 eventsAn upper level trough combined with ample moisture to produce very heavy rainfall across most of Puerto Rico.
• Flooding in Montana, May 20 to 31, 20112 deaths · $14 million · 13 eventsA Pacific low moved into the four corners region on the 17th and migrated northeast into the Dakotas through the 22nd, bringing another round of heavy precipitation aided by a tap of Gulf of Mexico moisture.
• Flood in Wyoming, May 20 to 23, 2011$520,000 · 1 eventA Pacific low moved into the four corners region on the 17th and migrated northeast into the Dakotas through the 22nd, bringing a round of heavy precipitation aided by a tap of Gulf of Mexico moisture.
• Flooding in Montana, May 20 to 29, 20119 eventsThis flooding occurred in a large portion of northeast Montana.
• Heavy Rain in North Dakota, May 20, 20116 eventsA slow moving upper level low pressure system brought widespread rainfall to west and central North Dakota on May 20th. A few areas received heavy amounts of precipitation, which contributed to increased river levels and ongoing overland flooding.
• Flash Flooding and Flood in Texas, May 20, 2011$110,000 · 1.75 in hail · 32 eventsScattered thunderstorms developed across North Texas and primarily produced hail that was less than golfball sized in diameter. There were a couple of reported microbursts as well.
• Flash Flooding and Hail in New York, May 20, 20110.75 in hail · 9 eventsA vertically stacked upper level low moved slowly over eastern Pennsylvania, New Jersey and southern New York on Friday, May 20th. The surface low moved to near Long Island by the early afternoon.
• Flash Flooding and Lightning Strike in Vermont, May 20, 2011$585,000 · 5 eventsSlow moving thunderstorms produced excessive runoff across portions of Vermont, resulting in localized flash flooding.
• Flood in South Dakota, May 20 to 31, 2011$300,000 · 1 eventHeavy rain runoff on saturated ground caused record flooding along the Little Missouri River.
• Flooding in Arkansas, May 21 to 31, 2011$105,000 · 7 eventsAdditional heavy rainfall and additional releases from area lakes caused some rivers to rise back above flood stage during the month of May.
• Flooding in Montana, May 21 to 31, 20113 eventsFlooding due to excessive rainfall and snowmelt caused Belt Creek to become flooded. Flooding emergency declared for Cascade county on 5/23/11.
• Flash Flood and Hail in Nebraska, May 21, 20111.75 in hail · 27 eventsScattered severe thunderstorms developed over eastern Nebraska during the afternoon of May 21 and tracked and developed into western Iowa during the early to mid evening hours.
• Flash Flooding in Maine, May 21, 2011$130,000 · 2 eventsTraining showers and thunderstorms dropped 2 to 4 inches of rain in a very short period of time causing road washouts and culvert failures. An observer in Greene reported 3.5 inches of rain in 30 minutes.
• Flooding in Utah, May 22 to 31, 2011$710,000 · 4 eventsWarm temperatures and fast snowmelt caused widespread river flooding across Utah through the end of May. Major rivers impacted included the Sevier River, the South Fork of the Ogden River, and much of the Weber River system. Note that this episode continued into June.
• Flood in North Dakota, May 22 to 29, 2011$50,000 · 1 eventThis was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains. Flooding was along the Little Missouri River through Medora.
• Flooding in Iowa, May 22 to 31, 20112 eventsHeavy rain brought the lower Big Sioux River back above flood stage in late May, with minor to moderate flooding.
• Flooding in Iowa, May 22 to 31, 20112 eventsHeavy rain brought the Little Sioux River back above flood stage in late May, with minor flooding reported.
• Flooding in Montana, May 22 to 31, 20114 eventsHeavy rain that resulted in swollen tributaries contributed to high river levels on the Milk that lasted well into June in some places.
• Flooding in South Dakota, May 22 to 26, 20113 eventsMinor to moderate flooding occurred along the Belle Fourche River from the South Dakota-Wyoming state line downstream to the confluence of the Cheyenne River.
• Flash Flood and Flood in Ohio, May 22, 2011$61,000 · 2 in hail · 26 eventsA weak mid level shortwave combined with moderate instability to produce severe thunderstorms with hail. These storms later evolved into heavy rain producing storms.
• Flooding in Iowa, May 22 to 31, 2011$525,000 · 9 eventsAs has been the case in recent months, Iowa saw many large variations in temperature. The first six days of the month were much cooler than usual with temperatures falling to 20 at Sibley and Spencer on the 3rd.
• Flash Flooding and Hail in Virginia, May 22 to 23, 2011$15,000 · 1.75 in hail · 23 eventsScattered thunderstorms spread eastward from a strong mesoscale system over Kentucky and Tennessee in the early evening and continued for several hours.
• Flash Flood and Hail in North Carolina, May 22, 20111.75 in hail · 4 eventsScattered thunderstorms spread eastward from a strong mesoscale system over Kentucky and Tennessee in the early evening and continued for several hours.
• Flood in Wyoming, May 22 to 29, 2011$30,000 · 1 eventLower elevation snowmelt in the southern Wind River Range generated minor flooding along the Sweetwater River.
• Flash Flooding in Missouri, May 22 to 25, 2011$1.8 million · 17 eventsA slow moving upper level trough and low pressure system across the central plains region moving across the Ozarks caused numerous heavy showers and storms that produced heavy rainfall. This lead to additional flooding and flash flooding across the Ozarks.
• Flash Flood and Hail in Tennessee, May 22 to 23, 20111 in hail · 4 eventsA broad upper level trough over the center of the country combined with a leftover outflow boundary across the Mid-South to produce numerous thunderstorms over Southwest Tennessee and Northeast Arkansas.
• Flash Flooding and Hail in Kentucky, May 23, 20111 in hail · 28 eventsDuring the predawn hours of May 23 an MCS moved in from the west and pushed across the region. Additionally, convection fired ahead of the MCS in the moist atmosphere with the storms being fueled by a 50 kt. LLJ.
• Flooding in Montana, May 23 to 31, 20112 eventsHeavy rain and some mountain snowmelt contributed to flooding of especially the Flatwillow Creek and the Musselshell River.
• Flooding in Montana, May 23 to 29, 20114 eventsA slow moving upper level low pressure system was tapping into an area of moisture that was surging north from the southern Plains states. 2 to 4 inches of rain fell across the area between May 20th and the 22nd.
• Flash Flooding and Flood in Ohio, May 23, 2011$14,000 · 3 eventsA short wave trough moved eastward across the area during the morning hours. The main threat from these storms was flooding.
• Flash Flood and Flood in Texas, May 23, 2011$51,000 · 1.75 in hail · 24 eventsThunderstorms developed near the Metroplex during the late morning hours. These storms produced hail that was mostly nickel to quarter sized in diameter. Heavy rainfall led to some localized flooding in the Metroplex.
• Flooding in Montana, May 23 to 31, 2011$6.0 million · 3 eventsA Pacific low moved into the four corners region on the 17th and migrated northeast into the Dakotas through the 22nd, bringing another round of heavy precipitation aided by a tap of Gulf of Mexico moisture.
• Flash Flooding and Hail in Arkansas, May 23 to 24, 20114 deaths · $51,000 · 1 in hail · 20 eventsThunderstorms developed during the early morning hours across northeastern Oklahoma and southeastern Kansas in response to an approaching upper level disturbance and increasing low level jet.
• Flash Flood and Damaging Winds in New York, May 23, 2011$110,000 · 52 kt wind · 5 eventsThunderstorms developed in warm, humid air as a cold front approached the region during the afternoon hours. The thunderstorms produced wind gusts measured to 52 knots. The thunderstorm winds downed trees and power lines in Findley Lake, Clymer, Panama and Busti.
• Flash Flooding and Hail in Kentucky, May 24, 2011$155,000 · 1 in hail · 26 eventsSeveral rounds of strong to severe thunderstorms caused sporadic wind damage and dropped up to nickel size on portions of eastern KY throughout the day on May 24th.
• Flooding and Heavy Rain in Kansas, May 24 to 25, 2011$1.1 million · 8 eventsThe time frame between the early morning hours of Tuesday the 24th into the day on Wednesday the 25th brought widespread heavy rainfall and flooding to much of North Central Kansas, in what turned out to be the second of three significant heavy rainfall events within a 2-week…
• Flash Flooding and Damaging Winds in Kansas, May 24, 20111 injured · $17,000 · 61 kt wind · 10 eventsA strong upper level trough across the central plains region and an upper level disturbance along with a frontal boundary in the area produced numerous severe storms.
• Flash Flood and Hail in North Carolina, May 24, 2011$10,000 · 2 in hail · 24 eventsTwo distinct upper level storm systems passed through the area, one in the late morning, the second during the late afternoon and early evening. Each brought a round of active severe weather to the region.
• Flash Flooding and Flood in Colorado, May 24, 20111 in hail · 8 eventsA slow-moving upper low pressure area moved across the region during the afternoon. A line of severe thunderstorms developed over Colorado in the morning and moved into western Kansas during the afternoon.
• Flash Flooding in Montana, May 24, 20111 death · 2 eventsA slow moving area of thunderstorms produced heavy rain over Western Big Horn and South Central Yellowstone Counties.
• Flash Flood in Wyoming, May 24, 2011$50,000 · 1 eventFlash flooding occurred in Upton when a slow moving thunderstorm brought two inches of rain in less than one hour.
• Flooding and Heavy Rain in Nebraska, May 24 to 25, 2011$2.1 million · 15 eventsFor western and southern portions of South Central Nebraska, the time frame from the early morning hours of Tuesday the 24th through the day on Wednesday the 25th ended up being the overall rainiest 36-hour period of the spring.
• Flood in Wyoming, May 24 to 31, 2011$25,000 · 1 eventSnowmelt and rain combined to raise water levels on the Salt River in Star Valley.
• Flash Flooding and Hail in Illinois, May 25 to 26, 2011$40,000 · 1 in hail · 8 eventsA low pressure system brought showers and thunderstorms to eastern Iowa, northeast Missouri, and northwest Illinois during the afternoon and evening of May 25.
• Flooding in Michigan, May 25 to 26, 2011$200,000 · 2 eventsTwo to four inches of rain fell along the I-94 corridor leading to flooding.
• Flash Flood and Hail in Illinois, May 25, 20111.75 in hail · 21 eventsStrong area of low pressure moved into the forecast area with a dry line out ahead of the main cold front. Storms fired up along and just ahead of the dry line beginning in the early afternoon hours.
• Flash Flood and Damaging Winds in Missouri, May 25, 201152 kt wind · 3 eventsA low pressure system brought showers and thunderstorms to eastern Iowa, northeast Missouri, and northwest Illinois during the afternoon and evening of May 25.
• Flash Flood and Hail in Indiana, May 25, 2011$29,000 · 3 in hail · 16 eventsA strong low pressure system west of the Ohio Valley approached during peak heating on May 25th. This resulted in the development of widespread severe thunderstorms with large hail and damaging winds during the afternoon and evening hours.
• Flash Flood and Hail in Mississippi, May 25, 20111.25 in hail · 12 eventsA developing surface low moved into the Mid Mississippi Valley while the associated cold front moved toward the Mid South on the afternoon of May 25, 2011.
• Flash Flooding and Hail in Mississippi, May 25 to 26, 2011$317,000 · 2 in hail · 20 eventsA powerful, late season, low pressure system brought numerous thunderstorms to the Deep South starting late in the evening of May 25th, continuing into the early morning hours of May 26th. Several of these storms produced large hail and damaging winds.
• Flood in Washington, May 26 to 31, 2011$300,000 · 1 eventThis river flooding episode continues into June. A series of weather disturbances brought heavy rainfall to the Pacific Northwest. The heavy rainfall combined with snowmelt runoff led to flooding on the Columbia River.
• Flooding in Nebraska, May 26 to 31, 2011$60,000 · 4 eventsHigh releases from upstream reservoirs brought increasing flows and flooding along the Missouri River downstream of Gavins Point Dam.
• Flooding in Iowa, May 26 to 31, 2011$15,000 · 2 eventsHigh releases from Gavins Point Dam caused the Missouri River to begin flooding upstream of the Platte River beginning in mid to late May. The flooding continued into June.
• Flash Flooding and Flood in Vermont, May 26 to 27, 2011$11 million · 2.5 in hail · 83 eventsA surface low as well as upper atmospheric energy traveled along a quasi-stationary boundary across northern New York and Vermont during the afternoon and evening of May 26th.
• Flash Flood and Hail in Virginia, May 26, 2011$195,000 · 1.75 in hail · 34 eventsThe atmosphere quickly became very unstable on the afternoon of May 26th, which resulted in the development of severe thunderstorms, mainly in the mountains and foothills. These storms were primarily large hail producers.
• Flash Flood and Hail in North Carolina, May 26, 2011$21,000 · 1.75 in hail · 11 eventsThe atmosphere quickly became unstable during the afternoon of May 26th resulting in the development of severe thunderstorms in northwest North Carolina. The first storms were primarily hail producers, but in the evening, a line of storms started forming in Western NC.
• Flash Flooding and Flood in New Hampshire, May 26 to 27, 2011$1.1 million · 8 eventsA stationary front located through northern New Hampshire provided a focus for showers and thunderstorms to develop. Due to the slow movement of the storms rainfall rates were high resulting in flash flooding.
• Debris Flows and Flooding in Washington, May 27 to 31, 2011$39,000 · 4 eventsA wet spring season continued for the Inland Northwest during the last week of May as another, wet storm system moved through the region producing in the neighborhood of half to one and a half inches of liquid precipitation over Northern Washington May 25-26th.
• Flash Flooding and Hail in North Carolina, May 27, 2011$27,000 · 1.75 in hail · 25 eventsWith moisten laden air in place, a series of upper level disturbances in advance of an upper level trough moving into the area from the Tennessee Vally produced heavy rainfall of 3 to 5 inches along with severe hail and and isolated thunderstorm wind damage.
• Flash Flooding and Debris Flows in Puerto Rico, May 27 to 28, 201112 eventsAmple low level moisture combined with strong daytime heating and local effects to produce numerous showers with thunderstorms across the Cordillera Central.
• Flash Flooding and Damaging Wind in New York, May 27 to 28, 2011$910,000 · 50 kt wind · 4 eventsA surface low as well as upper atmospheric energy traveled along a quasi-stationary boundary across northern New York during the afternoon of May 27th.
• Flash Flooding in Maryland, May 27, 20116 eventsA nearly stationary front drifted east into western Maryland during the afternoon. Thunderstorms trained over the same area for several hours across locations that had saturated ground. Flash flooding resulted in Allegany County.
• Flash Flooding and Hail in New York, May 28, 2011$13 million · 1.75 in hail · 11 eventsA warm and humid air mass was over the region and had been in place for several days. A slow moving surface boundary was draped across the North Country and extended westward towards western New York and Lake Ontario.
• Flash Flood and Flooding in Illinois, May 28, 20110.88 in hail · 4 eventsStrong thunderstorms moved across parts of northern Illinois during the late afternoon and evening hours of May 28th, producing small hail and heavy rain, which produced some flooding.
• Flash Flood and Hail in Illinois, May 29, 2011$213,000 · 1 in hail · 7 eventsThunderstorms initiated across eastern Iowa during the morning of May 29th, then tracked eastward along a stationary frontal boundary into north-central Illinois. A large bow echo signature developed, with the strongest winds remaining north of a Galesburg to Henry line.
• Flash Flood and Hail in Illinois, May 29, 2011$106,000 · 1 in hail · 11 eventsA warm front stretching from southwest Kansas to northern Ohio pushed humid air into eastern Iowa, northeast Missouri, and northwest Illinois during the early morning hours of May 29.
• Flash Flooding and Flooding in Illinois, May 29, 2011$555,000 · 1 in hail · 17 eventsStrong to severe thunderstorms moved across many areas of northern Illinois from late morning through late afternoon on May 29th producing damaging winds, large hail and heavy rain, which caused flash flooding in some areas.
• Flooding in Iowa, May 29 to 30, 2011$110,000 · 3 eventsAnother storm system moved across the state late in the month. The heaviest rain fell over the south half of the state. This resulted in a short duration flooding event along the lower Des Moines River Basin and its tributaries.
• Flash Flooding in Vermont, May 30, 2011$125,000 · 2 eventsThunderstorms developed along a nearly stationary cold front across central and northeast Vermont. Heavy rainfall from the storms produced localized flash flooding.
• Flooding in Montana, May 29 to 31, 20114 eventsAn additional two inches of rain fell across the area, bringing flooding to creeks and streams in the area.
• Flash Flooding in New Hampshire, May 30 to 31, 2011$321,000 · 6 eventsA stationary front located through northern New Hampshire provided a focus for showers and thunderstorms to develop. Due to the slow movement and the training of the storms rainfall rates were high and resulted in flash flooding.
• Flash Flood and Damaging Winds in Michigan, May 30, 2011$2,000 · 58 kt wind · 8 eventsA low pressure system approaching from the Northern Plains triggered thunderstorms with heavy rain over portions of western Upper Michigan on the afternoon of the 30th. A severe thunderstorm produced wind gusts in excess of 60 mph at Freda in Houghton County.
• Lakeshore Flood in Vermont, June 1 to 18, 20115 eventsRecord Flooding occurred along the shores of Lake Champlain from mid-April to mid-June.
• Flooding in Nebraska, June 1 to 30, 20112 deaths · $4.3 million · 11 eventsA record rain event in May in eastern Montana combined with high water from storms in April and May (and early spring snow melt) and brought high water to the Missouri River chain of reservoirs.
• Flooding in Mississippi, June 1 to 17, 2011$959,000 · 4 eventsThe flood of 2011 had its birth around the end of March when heavy rainfall of 2 to 5 inches fell across Arkansas, Southeast Missouri, and the Ohio River Valley.
• Flooding in Iowa, June 1 to 30, 2011$880,000 · 5 eventsA record rain event in May in eastern Montana combined with high water from other storms in April and May and brought high water to the Missouri River chain of reservoirs. Water levels were further increased by the melting of a above normal snow pack in the northern Rockies.
• Flooding in Louisiana, June 1 to 17, 2011$900,000 · 3 eventsThe flood of 2011 had its birth around the end of March when heavy rainfall of 2 to 5 inches fell across Arkansas, Southeast Missouri, and the Ohio River Valley.
• Flooding in Arkansas, June 1 to 30, 2011$495,000 · 9 eventsAreal flooding continued into June, mainly in eastern parts of Arkansas. As water on the Mississippi River finally subsided, rivers in Arkansas were allowed to drain. In turn, the water level on smaller creeks and bayous decreased, allowing water to drain off of farmlands.
• Flooding in North Dakota, June 1 to 30, 2011$510,000 · 3 eventsWet weather continued through the month of June, causing the levels of Devils Lake and Stump Lake to hold fairly steady. Devils Lake started the month with an elevation of roughly 1454.25 feet MSL and ended the month of June at an elevation of roughly 1454.30 feet MSL.
• Flooding in Iowa, June 1 to 8, 2011$450,000 · 3 eventsFlooding that took place along the upper part of the Des Moines River Basin continued into the first part of June. Favorable conditions allowed the river to fall slowly through the first week with the flooding finally ending by the 8th.
• Flooding in Illinois, June 1 to 30, 2011$320,000 · 10 eventsThe weather pattern began to quiet down after the historic spring river flooding. With high pressure generally in control of the weather, the first half of June was very warm and dry.
• Flooding in Arkansas, June 1 to 30, 2011$360,000 · 7 eventsHeavy rainfall in April and May kept some rivers across the state above flood stage from late April through part of June. The White River at Augusta remained above flood stage from the last week of April through early July.
• Flooding in Missouri, June 1 to 30, 2011$30,000 · 6 eventsThe weather pattern began to quiet down after the historic spring river flooding. With high pressure generally in control of the weather, the first half of June was very warm and dry.
• Flooding in Indiana, June 1 to 7, 2011$20,000 · 2 eventsThe weather pattern began to quiet down after the historic spring river flooding. With high pressure generally in control of the weather, the first half of June was very warm and dry.
• Flooding in South Dakota, June 1 to 30, 20117 eventsMissouri River flooding continued in June with the river rising to record levels and having major impacts. The flooding forced evacuations of populated areas, affecting many homes, businesses, parks, recreation areas and other lowlands.
• Flooding in South Dakota, June 1 to 30, 20116 eventsModerate to major flooding on the James River continued through the month, with the river very slowly falling, then rising again due to heavy rains. Farmland and several roads near the river were flooded.
• Flooding in North Dakota, June 1 to 30, 20114 eventsThis was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains, not only in North Dakota but in Montana as well.
• Flooding in North Dakota, June 1 to 30, 20114 eventsThis was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains, not only in North Dakota but in Saskatchewan, Canada, as well.
• Flooding in Kentucky, June 1 to 3, 20114 eventsThe weather pattern began to quiet down after the historic spring river flooding. With high pressure generally in control of the weather, the first half of June was very warm and dry.
• Flooding in Iowa, June 1 to 30, 20113 eventsMinor to moderate flooding of the lower Big Sioux River continued in June. The water levels varied, with the river falling a little below flood stage for a few days in the middle of the month, rising above flood stage again due to heavy rains, then beginning to fall again near…
• Flooding in South Dakota, June 1 to 30, 20113 eventsSpring flooding along with additional heavy rainfall in June kept or brought several rivers and creeks above flood stage.
• Flooding in South Dakota, June 1 to 30, 20113 eventsFlooding from May along with much above normal June rainfall kept parts of northeast South Dakota flooded throughout June. The counties mainly affected were Brown, Spink, and Edmunds. Crop and pastureland along with many roads remained flooded throughout the month.
• Flooding in Utah, June 1 to 15, 2011$400,000 · 4 eventsWarm temperatures along with occasional heavy rain led to continued flooding across the state of Utah. Major rivers that experienced flooding included the Weber River, the Sevier River, and the South Fork of the Ogden River. Note that this episode began in May.
• Flood in Utah, June 1 to 30, 2011$125,000 · 1 eventSnow melt from a record snowpack caused extended high flows and river flooding on the main stem of the Colorado and Green Rivers in Grand County.
• Flood in Colorado, June 1 to 30, 2011$125,000 · 1 eventA record snowpack along the Colorado River basin caused an extended period of high river flows along the Colorado River across Mesa County in June.
• Flood in Utah, June 1 to 30, 2011$50,000 · 1 eventRapidly warming temperatures increased the runoff from a record snowpack over the Northeastern Utah mountains. This resulted in an extended period of high flows along many area waterways.
• Flooding in Montana, June 1 to 29, 20113 eventsSwollen tributaries contributed to high river levels on the Milk River in Valley County.
• Flooding in Montana, June 1 to 4, 20113 eventsSignificant rainfall combined with higher elevation snowmelt the last half of May 2011 resulted in significant flooding along the Musselshell River. This flooding lingered into the month of June. Please see May 2011 Storm Data for the main impacts and damage estimates.
• Flood in Washington, June 1 to 18, 2011$1.2 million · 1 eventThis river flooding episode continues from May. A series of weather disturbances brought heavy rainfall to the Pacific Northwest. The heavy rainfall combined with snowmelt runoff to produce flooding on the Columbia River.
• Flooding in Washington, June 1 to 17, 2011$5,000 · 3 eventsFollowing a very wet April and May, warmer June temperatures began to melt an above normal mountain snowpack increasing flows into already swollen river basins.|This caused minor flooding along the Okanogan River along with several of its smaller tributaries.
• Flash Flooding and Lightning Strikes in Hawaii, June 1 to 5, 20111 injured · $20,000 · 15 eventsAn upper low in the area caused showers and thunderstorms--even snow--over the Aloha State. Some of the rain was heavy enough to produce flash flooding over parts of the island chain. The costs of any property damage were not available.
• Flash Flooding and Flooding in Kansas, June 1 to 2, 2011$500 · 4.5 in hail · 87 eventsOn the afternoon of June 1, severe thunderstorms formed across northeast Kansas as a warm front lifted northward through the area. Most of these storms produced severe hail up to the size of golf balls, but some of the stronger storms brought hail up to the size of baseballs.
• Flash Flood and Hail in Kansas, June 1, 2011$25,000 · 1.75 in hail · 13 eventsScattered severe thunderstorms were observed across extreme eastern Kansas, during the evening hours of June 1, 2011. There were several reports of hail and damaging winds.

Every billion-dollar disasterEvery storm of 2011Tornadoes in 2011

NOAA NCEI, U.S. Billion-Dollar Weather and Climate Disasters (2025), https://doi.org/10.25921/stkw-7w73, and the Storm Events Database for the episodes.