Thunderstorms with heavy rain moved across portions of northeast Iowa during the evening of September 3rd. 5 to 4 inches produced some flash flooding across Allamakee and Clayton Counties.
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 ARX wrote it up.
Thunderstorms with heavy rain moved across portions of northeast Iowa during the evening of September 3rd. Rainfall amounts of 1.5 to 4 inches produced some flash flooding across Allamakee and Clayton Counties. High water was reported in and around Dorchester (Allamakee County) and a mudslide occurred north of Marquette (Clayton County).
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 La Crosse, WI wrote its last area forecast discussion before the first event at Sep 2, 5:44 PM CST, 2 hours 41 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 644 PM CDT Sun Sep 2 2018 .SHORT TERM...(This evening through Monday) Issued at 208 PM CDT Sun Sep 2 2018 While there will be showers and storms around the area through Monday, this is looking to be a relative lull in the heavy rain threat. The boundary that had been south of the area the last couple of days has become very diffuse. Still some hint of it across central Iowa where there is a subtle wind shift and slight increase in the dew points. There is also a cold front moving southeast across Minnesota as high pressure builds in behind the front over the Dakotas. Looking at several runs of the RAP and the 03.12Z NAM, it looks like both of these boundaries will be a player for the local area. The weak boundary across Iowa is expected to shift north through the evening while become even more diffuse while the cold front gets pushed to about the Interstate 90 corridor overnight as the high pressure moves east toward Lake Superior. The low level moisture transport axis looks to be from Missouri into lower Michigan, well ahead of the advancing cold front. The ML CAPE axis also looks to remain southeast of the area, but enough remains to maintain at least a threat of thunder. The main axis of showers and storms is expected to gradually shift southeast across the area this evening and primarily be out of the area for much of the overnight hours. The boundary pushed in by the area of high pressure tonight will start to lift back to the north as a warm front Monday. This will allow the moisture transport axis to shift back to the west and while still weak, will be focused more into the area. This should allow for a general increase in showers and storms through the day, especially south of Interstate 90. While there could be a brief period of heavy rain the storms Monday, there does not look to be a threat of widespread heavy rain or flash flooding with the general weak moisture transport and the highest precipitable waters remaining south of the area. .LONG TERM...(Monday night through Sunday) Issued at 208 PM CDT Sun Sep 2 2018 Main concern is possible heavy rain/flood threat through mid-week. The surface boundary is forecast to lift northward across the area as a warm front Monday night ahead of an upper shortwave trough. Warm advection and increasing low-level moisture transport will help to foster showers/storms. The 02.12Z NAM focuses the strongest moisture transport and convection north and west of the area. However, confidence in details in this type of scenario with a boundary lifting north is not all that high at this range given potential contamination from convection. Locally heavy rainfall will be possible with any storms given the environment. If the warm front does lift north of the area could see a relatively quiet Tuesday morning until the cold front approaches from the west. At least modest mid-level height falls ahead of the broad upper will overspread the region Tuesday afternoon and night. Expect showers/storms to increase as the front slowly sags south Tuesday into Wednesday. A very warm, anomalously moist environment will favor the potential for heavy rain/flooding. Some uncertainty remains as to where this potential will be highest and the degree of training of storms that will occur along the front. However, the later Tuesday into Wednesday period will be one to watch closely, though, especially given antecedent conditions. Mid-level flow/shear remains on the marginal side south of the front and lapse rates are weak, but could see a few stronger storms later Tuesday. As the upper waves passes to the east, surface high pressure will begin to build south on Wednesday with drying across northern parts of the area. A generally weak upper flow pattern is expected late this week. Surface high pressure across the northern Great Lakes should lead to a period of drier weather late this week into the weekend over much of the area. However, given the weak flow and suggestion that various shortwaves may lift northeastward in weakly confluent flow on the western periphery of the Southeast/Mid-Atlantic ridge, some shower/storm chances may persist into late week, especially across southern areas. Temps will cool from the 70s to low 80s early this week to the upper 60s and 70s later this week behind the front. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 644 PM CDT Sun Sep 2 2018 Showers and storms are southeast of LSE and RST and should remain there for much if not all of tonight, with winds becoming light as a weakening frontal boundary slides into the area. With earlier rain, light winds, and some breaks in the sky cover at times (just mainly high clouds), fog should be a pretty good bet later tonight, some of which will become dense fog both LSE and RST. Not entirely sure just how fast fog will develop, but a good first guess is roughly 04-07Z, with the thickest fog expected either side of sunrise, when visibility could be 1/4 mile or less, particularly at RST (though possible at LSE as well). Fog will likely lift into a stratus layer for a time Monday morning, perhaps trying to scatter out for the afternoon as some additional showers and storms attempt to develop later in the day. Confidence is low in how much coverage of storms will exist through 00Z, with much better chances arriving into Monday evening and night. && .HYDROLOGY... Issued at 208 PM CDT Sun Sep 2 2018 The highest potential for additional heavy rains and possible flash flooding, appears to be focused on the late Tuesday afternoon into Tuesday night period. The next cold front will be advancing into the area with strong moisture transport focused into the front. An axis of high precipitable waters, possibly in excess of 2 inches, will reside ahead of the front. The concern is how far north will the nose of the moisture transport axis be to focus the heaviest rain threat. Also uncertain how much training there will be ahead of the north/south oriented front that looks to be fairly progressive. Flooding continues along the Kickapoo River and for now, levels continue to go down. See the latest flood statement for more details. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && SHORT TERM...04 LONG TERM...JM AVIATION...Lawrence HYDROLOGY...04
Hazardous Weather Outlook National Weather Service La Crosse WI 425 AM CDT Sun Sep 2 2018 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029- 032>034-041>044-053>055-061-031000- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston- Taylor-Clark-Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau- Adams-Vernon-Crawford-Richland-Grant- 425 AM CDT Sun Sep 2 2018 This Hazardous Weather Outlook is for portions of southeast Minnesota...northeast Iowa and southwest into central Wisconsin. .DAY ONE...Today and Tonight Periods of showers and storms. Heavy rain possible with most thunderstorms, with the potential for localized flooding. A few stronger storms could also develop, bringing stronger wind gusts and small hail. .DAYS TWO THROUGH SEVEN...Monday through Saturday Periodic rounds of showers and storms are expected through Wednesday night. The heavy rain threat appears localized Tuesday, but more widespread from late Tuesday night through Wednesday night. Several inches of rain could fall during this period. With wet soils unable to hold much more rain, heavy rainfall would likely result in localized to widespread flooding. A few stronger storms are also possible. After Wednesday night, small shower and storm chances are generally confined to small sections of northeast Iowa and southwest Wisconsin. .SPOTTER INFORMATION STATEMENT... Rainfall reports are appreciated. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled.
Special Weather Statement
National Weather Service La Crosse WI
328 PM CDT SUN SEP 2 2018
IAZ030-WIZ061-022130-
Clayton-Grant-
328 PM CDT SUN SEP 2 2018
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT EASTERN CLAYTON AND
GRANT COUNTIES...
At 327 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Guttenberg to Delhi. Movement was
east at 35 mph.
Winds in excess of 40 mph and pea size hail are possible with these
storms.
Locations impacted include...
Platteville, Lancaster, Guttenberg, Boscobel, Fennimore, Cuba City,
Muscoda, Hazel Green, Dickeyville, Cassville, Garnavillo,
Bloomington, Preston, Georgetown, Beetown, Arthur, Montfort, Wauzeka,
Potosi and Livingston.
Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4264 9071 4268 9090 4265 9090 4265 9138
4293 9136 4300 9116 4299 9116 4300 9113
4299 9106 4306 9094 4308 9085 4312 9074
4317 9070 4320 9058 4320 9043 4251 9042
4251 9064
TIME...MOT...LOC 2027Z 247DEG 31KT 4272 9114 4241 9132
CAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
432 PM CDT SUN SEP 2 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0428 PM TSTM WND DMG DICKEYVILLE 42.63N 90.59W
09/02/2018 GRANT WI LAW ENFORCEMENT
REPORTS OF TREES AND POWER LINES DOWN NEAR
DICKEYVILLE. STILL RECEIVING ESTIMATED WINDS
AROUND 60 MPH.
&&
LAWRENCEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
440 PM CDT SUN SEP 2 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0356 PM TSTM WND DMG LANCASTER 42.85N 90.71W
09/02/2018 GRANT WI LAW ENFORCEMENT
NUMEROUS REPORTS OF TREES AND SOME POWER
LINES DOWN NEAR AND WEST OF LANCASTER.
REPORT TIME BASED ON RADAR.
&&
LAWRENCEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
442 PM CDT SUN SEP 2 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0420 PM FUNNEL CLOUD DICKEYVILLE 42.63N 90.59W
09/02/2018 GRANT WI TRAINED SPOTTER
SEVERAL REPORTS OF A FUNNEL CLOUD FROM
SEVERAL STORM SPOTTERS. RELAYED BY GRANT
COUNTY DISPATCH.
&&
LAWRENCEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
443 PM CDT SUN SEP 2 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0315 PM NON-TSTM WND GST PLATTEVILLE MUNICIPAL A 42.69N 90.44W
09/02/2018 M59 MPH GRANT WI AWOS
AWOS STATION PVB, PLATTEVILLE MUNICIPAL
AIRPORT.
&&
LAWRENCEThe La Crosse radar (KARX), 101 km away, was scanning. The volume nearest the first event began at 02:25 UTC.
5 flood, 2 flash flood. Local standard time, as filed.
Runoff from heavy rains pushed the Turkey River out of its banks near Eldorado. The river crested over two feet above the flood stage at 15.12 feet on September 6th.
Runoff from heavy rains pushed the Turkey River out of its banks near Elkader. The river crested just over four feet above the flood stage at 16.06 feet on September 5th.
Runoff from heavy rain caused high water in and around Dorchester.
Runoff from heavy rains pushed some streams out of their banks across Floyd County. The flooding closed some roads including 110th Street, 280th Street, 290th Street, 300th Street, Ivory Avenue and Ocean Avenue.
Runoff from heavy rain caused a mudslide to occur along State Highway 76 north of Marquette.
Runoff from heavy rains pushed the Turkey River out of its banks in Spillville. The river crested a half foot above the flood stage at 9.5 feet on September 4th. The river briefly fell below flood stage before going out of its banks again. The second crest was over four and a half feet above the flood stage at 13.67 feet on September 6th.
Runoff from heavy rains pushed the Turkey River out of its banks in Garber. The river crested over four feet above the flood stage at 21.24 feet on September 6th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2018Every state in 2018This day in weather historyWarnings in Iowa, September 2018
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: 785713, 785714, 781405, 786711, 781415, 785712, 785717.