A very powerful storm system moved through the southern Rockies during the night of the 10th and early morning of the 11th. Intense surface low pressure formed over western Kansas with a central pressure by sunrise on the 11th of 977 Mb.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS DMX wrote it up.
A very powerful storm system moved through the southern Rockies during the night of the 10th and early morning of the 11th. Intense surface low pressure formed over western Kansas with a central pressure by sunrise on the 11th of 977 Mb. The weather situation was very dynamic with 500 Mb winds over 100 kts and a very sharp dry punch clearly visible on the satellite pictures. During the day the warm front that extended east from the low reached into southern Iowa, then extended eastward. There were two things that occurred during the day. The first was a very strong supercell that formed over northern Missouri during the morning. This storm lifted north-northeast at about 50 kts into Iowa, producing a long track tornado with a path extending nearly all the way to Des Moines. During the afternoon the warm front surged north with the northeast progression of the surface dry line. Dew points rose into the mid 60s to the south of the warm front across much of the southeast half to two thirds of Iowa. Surface temperatures in these areas reached the 60s north, with 70s south. With the atmosphere primed, the dry line began to move into Iowa. Dew point temperatures behind the dry line were in the 30s with southwest winds of 30 to 50 MPH. A broken squall line formed on the nose of the dry punch and became severe quickly. The storm cells themselves were not all that large, but nearly every cell along the line did carry a mesoscale circulation. There were several tornado touchdowns as the line lifted north as well. The primary severe weather during this even was the tornadic nature of it. There were reports of wind and hail, but everything considered these reports were pretty scattered. There were very few reports of wind and hail with the first supercell as it lifted north out of Missouri. One inch diameter hail was reported in Ringgold County east of Redding. Reports of winds and hail were more frequent with the second line of thunderstorms. There were numerous reports of hail up to marble size with this line, however there were not all that many reports of hail larger than that. A few reports of three quarter to one inch diameter hail were received from Marion and Polk Counties. The most significant hail occurred in northeast Iowa in Butler County. Golf ball size hail fell in the town of Parkersburg as the line passed over the city. There were more reports of wind with the second round. Nearly all locations reported winds of at least 50 MPH as the line passed overhead. Scattered reports of winds of 70 to 85 MPH were received. Wind damage occurred in Boone County as high winds downed power lines and downed outbuildings north of Ogden. The greatest wind damage occurred over northeast Iowa in Black Hawk and Franklin Counties. A building was blown off of its foundation and onto an adjacent road southwest of Hampton in Franklin County. A roof of a barn was damaged and a grain wagon was tipped over northwest of Hampton. Roof and house damage was reported over parts of Black Hawk County as well. Five injuries occurred in Warren County at Carlisle when winds of around 65 MPH toppled a school bus. Twenty one children were on board the bus when it overturned with 5 treated for minor injuries. Spotty damage was reported around the greater Des Moines metropolitan area. Several tornadoes occurred with this system. The most significant tornado entered southern Iowa around mid day. This tornado reached minimal F3 intensity just east of Mt. Ayr (Ringgold County). Property damage is estimated at over $500,000 in Ringgold county alone. Across the Des Moines area of responsibility, at least 15 homes were destroyed, and 60 residences were damaged as around a dozen tornadoes touched down. A supercell thunderstorm moved north from Missouri into southern Iowa late in the morning of April 11. The storm produced a tornado in northern Missouri and crossed into Iowa in Ringgold County. The storm, and tornado, moved north through Ringgold County with a continuous damage path half way through the county. The damage path continued north through northern Ringgold County, southeast Union County and into northwest Clarke County. In this area, the path was not continuous. Based on damage reports, the tornado continued to produce occasional damage in Madison County. Chaser reports indicate the tornado had a multi-vortex structure as it moved through Ringgold and Union Counties. The last reported sighting was in northern Polk County where a brief touchdown was reported with no damage. The storm likely produced one tornado from the Missouri border to Madison County with an intermittent damage track. Damage in Ringgold County was severe with initial estimates around $1 million. The county was later declared a federal disaster area by President Bush. A second tornado briefly touched down in northern Polk County. The touchdown in Polk County was indeed a separate tornado. Even though the tornado was from the same parent cell, the system had occluded and was in the process of forming a new tornado as it passed over the western part of the Des Moines area. Reports from this tornado indicate that at least 9 homes were damaged or destroyed, one business destroyed, and a school building damaged. In addition to losses to homes, one farmstead was hit with considerable damage and some livestock damage. A series of tornadoes formed on the heels of the supercell tornado as the dry line pushed into the state. Most of these were brief touchdowns, however the storms were moving around 60 MPH. Three tornadoes touched down in Boone County. The most significant tornado touched down north of Ogden. It produced a 3 mile long track up to 1/8 mile wide. Farm site hit along highway P70. Barn and grain bins destroyed, knocking out windows in house. Otherwise only minor damage to house. Debris scattered 1 mile to next farm site where there was minor damage to many buildings. Track continued north-northeast across highway E26 into the campground at Don Williams Lake. A storage building was destroyed, several trees downed, plus outhouses, picnic tables and signs were damaged. The damage track dissipated on the northeast side of the Don Williams Recreation Area. There were several brief touchdowns with relatively minor damage in Guthrie, Greene, and Hamilton Counties. A stronger tornado touched down in southeast Black Hawk County, causing significant damage to two homes in the La Porte City area. The most serious tornado in terms of loss of life occurred in Wapello County. A tornado developed in rural southern Wapello County, a mile southwest of Agency, Iowa, around 1600 CDT, on Wednesday, April 11. The tornado path was 50 to 100 yards wide with sporadic touchdowns toward the north-northeast for the next 6 miles. Survey responses indicated that the duration of impact at any one location was only 15 to 30 seconds as the tornado quickly moved through Agency and over farms at a 60 mph horizontal movement. The Odd Fellows Lodge in Agency was destroyed, and over 50 residences were damaged. Two women inside were killed, three people injured and three people had no injuries. As the storm moved through Agency, a garage was lifted and carried about 100 meters off of its foundation. The car inside was twisted and covered with debris. In another incident, one house was hit by the tornado causing damage to the house. The family dog was in the dog pen at the time. The tornado lifted the pen and twirled it through the air. The dog pen was deposited some distance downstream and what was truly amazing was the fact that the dog was uninjured. Following the tornado, U.S. Highway 34 was closed for 2 hours in order to removed debris from the highway. Governor Tom Vilsack visited the area during a storm survey. The governor spoke with Brenda Brock of the National Weather Service, Ellen Gordon, Administrator, Iowa Emergency Management Division, emergency management personnel (fire department, law enforcement, mayor) and the public. A proclamation for emergency disaster assistance was signed.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Des Moines, IA wrote its last area forecast discussion before the first event at Apr 11, 10:17 AM CST, 23 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
345 AM CDT WED APR 11 2001
JUST A QUICK UPDATE. TORNADO WATCH IN SW ZONES. DRY LINE PUSHING UP
INTO CWA FROM KA/MO WILL BRING SVR WX TO CWA THIS AFTERNOON. LOWERED
TEMPS THIS AFTERNOON ALSO.
.DSM...TORNADO WATCH TIL 4 PM SW ZONES
IA044-057-070-071-081-082-092-093-094
FLOOD WATCH CONTINUES FOR ENTIRE FA THRU 4 PM.
KNOLLHOFFPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
540 AM CDT WED APR 11 2001
TIME(CDT) .....CITY LOCATION..... STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0430 AM CARBON IA WIND DAMAGE
04/11/01 ADAMS REPORTED BY EMERGENCY
MANAGEMENT. ROOF BLOWN
OFF A BARN JUST
NORTHWEST OF CARBON.IAZ044-111200- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 556 AM CDT WED APR 11 2001 TORNADO WATCH #126 THAT WAS IN EFFECT FOR...CRAWFORD COUNTY... HAS BEEN CANCELLED. >
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
608 AM CDT WED APR 11 2001
TIME(CDT) .....CITY LOCATION..... STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0430 AM NODAWAY IA WIND DAMAGE
04/11/01 ADAMS REPORTED BY EMERGENCY
MANAGEMENT. ALONG HWY
34 AT NODAWAY CORNER.
18 TREES DOWN. OUT
BUILDING DESTROYED.
GARAGE CAVED IN.CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
620 AM CDT WED APR 11 2001
SYNOPSIS A STRONG LOW PRESSURE SYSTEM OVER SOUTHWEST COLORADO WILL
MOVE NORTHEAST ACROSS NORTHWEST IOWA LATER TODAY. WARM AND MOIST
UNSTABLE AIR WILL CONTINUE TO STREAM NORTHWARD AHEAD OF THIS SYSTEM.
SEVERAL SURFACE BOUNDARIES WILL INTERACT WITH THIS MOIST AND
UNSTABLE AIR MASS TO PRODUCE SIGNIFICANT SEVERE WEATHER ACROSS THE
DES MOINES NATIONAL WEATHER SERVICE FORECAST AREA. A WARM FRONT
ACROSS NORTHERN IOWA WILL AID THUNDERSTORMS ACROSS THAT AREA THIS
MORNING. OUTFLOW BOUNDARY PRODUCE BY CONVECTION THIS MORNING. THE
MAIN THREAT FOR SEVERE WEATHER WILL FOLLOW LATER THIS AFTERNOON AS A
SURFACE DRY LINE AND AN UPPER LEVEL LOW MOVES NORTHEAST ACROSS IOWA.
SUFFICIENT SHEAR AND INSTABILITY WILL MOVE UP ACROSS THE AREA THIS
AFTERNOON TO CREATE AN ENVIRONMENT FOR ORGANIZED THUNDERSTORMS AND
SEVERE WEATHER.
SEE SITE SPECIFIC DETAILS BELOW FOR MORE INFORMATION.
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-121100-
ADAIR-ADAMS-APPANOOSE-AUDUBON-BLACK
HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CASS-CERRO
GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-DECATUR-EMMET-FRANKLIN-GREENE-
GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-JASPER-KOSSUTH-LUCAS-
MADISON-MAHASKA-MARION-MARSHALL-MONROE-PALO
ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR-UNION-
WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT-
INCLUDING THE CITIES OF...ALGONA...AMES...ATLANTIC...BOONE...
CARROLL...CENTERVILLE...CHARITON...CRESTON...DENISON...DES MOINES...
ESTHERVILLE...FORT DODGE...GRINNELL...INDIANOLA...IOWA FALLS...
KNOXVILLE...LAMONI...MARSHALLTOWN...MASON CITY...NEWTON...
OSKALOOSA...OTTUMWA...PELLA...PERRY...WATERLOO...WAVERLY AND WEBSTER
CITY
548 AM CDT WED APR 11 2001
* EVENT TIMING... THIS MORNING FOR DAMAGING WINDS...LARGE HAIL AND
FLASH FLOODING. THIS AFTERNOON MODERATE IN ALL
CATEGORIES.
* THREAT CATEGORIES...
TORNADO.......... LOW THIS MORNING...MODERATE THIS AFTERNOON.
DAMAGING WINDS... MODERATE
LARGE HAIL....... MODERATE
FLASH FLOODING... MODERATE
* SPOTTER ACTIVATION OUTLOOK...MODERATE
* THIS IS A POTENTIALLY DANGEROUS SEVERE WEATHER SITUATION...
ESPECIALLY FOR THIS AFTERNOON. MONITOR LATER NATIONAL
WEATHER SERVICE STATEMENTS AND FORECASTS FOR UPDATED INFORMATION
DURING THIS EVENT. ADDITIONAL SEVERE THUNDERSTORM OR TORNADO
WATCHES WILL LIKELY BE ISSUED LATER THIS MORNING AND THIS
AFTERNOON.
-------------------------------------------------------------------
THREAT KEY:
TORNADO.......... ANY TORNADO OCCURRENCE
DAMAGING WINDS... WINDS >= 58 MPH
LARGE HAIL....... HAIL >= 3/4 INCH DIAMETER
FLASH FLOODING... FLOODING CAUSED BY HEAVY RAINS WITHIN 6 HOURS
OF RAIN EVENT. POSES THREAT TO LIFE OR
PROPERTY.
THREAT CATEGORY KEY: PROBABILITY OF THREAT OCCURRING WITHIN 25
MILES OF POINT WITHIN FORECAST AREA
NONE....... NOT EXPECTED. LESS THAN 5% ( 2% FOR TORNADOES)
LOW........ 5-15% (2-15% FOR TORNADOES)
MODERATE... 25-35%
HIGH....... 45% OR GREATER
SPOTTER ACTIVATION OUTLOOK KEY:
NOT EXPECTED
LOW........ ACTIVATION POSSIBLE BUT NOT LIKELY
MODERATE... POSSIBILITIES ABOUT 50-50
HIGH....... ACTIVATION LIKELY
FOR MORE INFORMATION ON PROBABILISTIC SEVERE WEATHER OUTLOOKS...GO
TO THE STORM PREDICTION CENTER WEBSITE AT
WWW.SPC.NOAA.GOV/PRODUCTS/OUTLOOK/PROBINFO.HTML .IAZ045>049-057>061-070>074-081>085-092>096-111245- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 651 AM CDT WED APR 11 2001 SEVERE THUNDERSTORM WATCH #129 THAT WAS IN EFFECT FORr MOST OF CENTRAL AND SOUTH CENTRAL IOWA HAS BEEN CANCELLED. THE THREAT OF SEVERE WEATHER HAS DIMINISHED. ADDITIONAL STRONG THUNDERSTORMS MAY MOVE BACK INTO THE AREA BY LATE MORNING AND EARLY AFTERNOON.
CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1012 AM CDT WED APR 11 2001
A STRONG LOW PRESSURE SYSTEM OVER WESTERN KANSAS WILL MOVE INTO
SOUTHWEST MINNESOTA BY THIS EVENING. A DRYLINE EXTENDING FROM
SOUTHERN NEBRASKA INTO EASTERN KANSAS WILL RACE NORTHEAST ACROSS
IOWA DURING THE DAY. ABUNDANT LOW LEVEL MOISTURE AND STRONG WIND
FLOW AND WIND SHEAR ALOFT WILL SET THE STAGE FOR SEVERE
THUNDERSTORMS AND POSSIBLY TORNADOES ACROSS IOWA TODAY. WIDESPREAD
RAIN AND THUNDERSTORMS AHEAD OF THE DRYLINE WILL ALSO CONTINUE TO
PRODUCE PONDING OF WATER AND RISES IN STREAMS...BUT STORMS DURING
THE AFTERNOON WILL BE MOVING NORTHEAST AT 50 MPH REDUCING THE FLASH
FLOOD THREAT.
SEE SITE SPECIFIC DETAILS BELOW FOR MORE INFORMATION.
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-112300-
ADAIR-ADAMS-APPANOOSE-AUDUBON-BLACK
HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CASS-CERRO
GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-DECATUR-EMMET-FRANKLIN-GREENE-
GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-JASPER-KOSSUTH-LUCAS-
MADISON-MAHASKA-MARION-MARSHALL-MONROE-PALO
ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR-UNION-
WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT-
INCLUDING THE CITIES OF...ALGONA...AMES...ATLANTIC...BOONE...
CARROLL...CENTERVILLE...CHARITON...CRESTON...DENISON...DES MOINES...
ESTHERVILLE...FORT DODGE...GRINNELL...INDIANOLA...IOWA FALLS...
KNOXVILLE...LAMONI...MARSHALLTOWN...MASON CITY...NEWTON...
OSKALOOSA...OTTUMWA...PELLA...PERRY...WATERLOO...WAVERLY AND WEBSTER
CITY
1012 AM CDT WED APR 11 2001
* EVENT TIMING...AROUND NOON IN SOUTHWEST IOWA...BY 3 PM IN AN ARC
FROM FORT DODGE TO DES MOINES TO OTTUMWA AND AROUND 6 PM FROM MASON
CITY TO WATERLOO.
* THREAT CATEGORIES...
TORNADO..........MODERATE
DAMAGING WINDS...MODERATE TO HIGH
LARGE HAIL.......LOW TO MODERATE
FLASH FLOODING...LOW
* SPOTTER ACTIVATION OUTLOOK...HIGH
* MISCELLANEOUS INFORMATION - THIS IS A POTENTIALLY DANGEROUS
WEATHER SITUATION WITH DAMAGING TORNADOES POSSIBLE. TORNADO WATCHES
WILL BE ISSUED FOR THE SOUTHWEST HALF OF IOWA THIS MORNING AND FOR
POINTS NORTH AND EAST IN THE AFTERNOON. REVIEW SEVERE WEATHER SAFETY
RULES AND LISTEN FOR UPDATED NATIONAL WEATHER SERVICE FORECASTS AND
WARNINGS.
-------------------------------------------------------------------
THREAT KEY:
TORNADO.......... ANY TORNADO OCCURRENCE
DAMAGING WINDS... WINDS >= 58 MPH
LARGE HAIL....... HAIL >= 3/4 INCH DIAMETER
FLASH FLOODING... FLOODING CAUSED BY HEAVY RAINS WITHIN 6 HOURS
OF RAIN EVENT. POSES THREAT TO LIFE OR
PROPERTY.
THREAT CATEGORY KEY: PROBABILITY OF THREAT OCCURRING WITHIN 25
MILES OF POINT WITHIN FORECAST AREA
NONE....... NOT EXPECTED. LESS THAN 5% ( 2% FOR TORNADOES)
LOW........ 5-15% (2-15% FOR TORNADOES)
MODERATE... 25-35%
HIGH....... 45% OR GREATER
SPOTTER ACTIVATION OUTLOOK KEY:
NOT EXPECTED
LOW........ ACTIVATION POSSIBLE BUT NOT LIKELY
MODERATE... POSSIBILITIES ABOUT 50-50
HIGH....... ACTIVATION LIKELY
FOR MORE INFORMATION ON PROBABILISTIC SEVERE WEATHER OUTLOOKS...GO
TO THE STORM PREDICTION CENTER WEBSITE AT
WWW.SPC.NOAA.GOV/PRODUCTS/OUTLOOK/PROBINFO.HTML .The national radar mosaic for the moment the first event began.
27 thunderstorm wind, 17 tornado, 9 hail. Local standard time, as filed.
Tornado moved our of Missouri into Ringgold County, across the county into Union County.
Tornado moved from Ringgold County, across Union County, into Clarke County.
Tornado moved from Union County into Clarke County, then moved into Madison County.
Tornado moved from Clarke County into Madison County before lifting.
Brief touchdown in open area north of Interstate 35/80.
Tracked through mostly open area southeast of Bayard and destroyed a barn.
Brief touchdown in open country.
Short lived tornado in mostly open area.
Brief touchdown with some minor damage in Paton.
School bus overturned by wind gust.
Relatively brief touchdown, destroyed a barn.
Tracked over mainly open country.
Brief touchdown with damage reported to trailers and a building.
Two farm buildings blown down in rural area south of Webster City.
Intermittent track through open country. Tornado moved into Marshall County northwest of Baxter.
Intermittent track as tornado moved in from Jasper County and roped out.
Quick moving tornado, touchdown with strongest part in Agency. Nine buildings with major damage, 43 with minor. Two buildings destroyed. Two dead, three injured.
Tornado with intermittent track over open country.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Thunderstorm Wind, Franklin | 2001-04-11 | 73 | Female | Business | Direct |
| Thunderstorm Wind, Franklin | 2001-04-12 | 61 | Female | Business | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2001Every state in 2001This day in weather historyThe tornado archive for Iowa, 2001Warnings in Iowa, April 2001
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5239050, 5239021, 5239051, 5239052, 5237286, 5239046, 5237287, 5239022, 5237291, 5239023, 5239024, 5239025, 5239026, 5237293, 5239027, 5237300, 5239034, 5239028, 5237306, 5237288, 5237292, 5237303, 5237289, 5239033, 5237290, 5239029, 5237301, 5239035, 5239036, 5239030, 5239031, 5237296, 5237294, 5237298, 5239038, 5237299, 5237302, 5239037, 5237295, 5239039, and more.