Flooding that began in late August ended in early September along the Lemonweir River and parts of the Kickapoo River. The lower end of the Kickapoo River also started flooding in late August and with another round of heavy rain on September 3rd, remained in flood for the first week and a half of September.
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.
Flooding that began in late August ended in early September along the Lemonweir River and parts of the Kickapoo River. The lower end of the Kickapoo River also started flooding in late August and with another round of heavy rain on September 3rd, remained in flood for the first week and a half of September.
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 Aug 31, 10:52 PM CST, 1 hour 8 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 1152 PM CDT Fri Aug 31 2018 .SHORT TERM...(This evening through Saturday night) Issued at 238 PM CDT Fri Aug 31 2018 Still lots of unknowns in the forecast but short range models are starting to give a somewhat clearer picture of what is expected to occur. Early this afternoon there was a cold front from extreme northwest Minnesota into North Dakota. A stationary front was parked across central Missouri into northern Kansas. While both of these features will be a player for the area, the front over Missouri is expected to be more relevant as it lifts back north as a warm front. Water vapor satellite showing a weak short wave trough embedded in the mean long wave trough over eastern Montana. This wave will push east tonight and stay to the north while pushing the cold front southeast across Minnesota. Showers and storms already starting to develop across northwest Minnesota ahead of this system and these will drop southeast toward the area this evening. This activity is not expected to be near the area until about the middle of the evening with the best chances expected to be across the north closer to the short wave trough. By late this evening and into the overnight, the front across Missouri will start to lift back to the north into Iowa. However, not sure how far north it will make it as it is currently be held back by ongoing convection just north of it. It may not move much until the low level jet kicks in late this evening. If the front can get back into southern or central Iowa, a round of showers and storms will develop along and north of it as the low level jet runs into the boundary. There is also a short wave trough coming across Nebraska that will provide additional forcing for the showers and storms to develop. Looking at several runs of the RAP and the 31.12Z NAM, the mid level frontogenesis in the 850-700 mb layer looks to be focused right into the southern sections of the forecast area. Expecting to see rapid growth of showers and storms north of this boundary during the late evening into the early overnight with this activity then persisting into Saturday morning before diminishing as the low level jet veers off to the east and weakens. The main threat from this activity will be the heavy rain/flooding potential, see the hydrology section below for more details. Some potential for large hail and damaging winds early in the storm cycle until a transition over to mainly heavy rain occurs overnight. The ML CAPE pool looks to primarily stay along and west of the Mississippi River and into southwest Wisconsin and looks to be in the 1000-2000 J/Kg range. The shear looks to primarily be in the 0-3 km layer and on the order of 20 to 25 knots. The 0-1 km shear will increase as the low level jet forms develops but this doesn't look to come into play as the storms should be elevated above this layer north of the boundary. This will leave some large hail and damaging winds then as the main threats outside of the heavy rain. The boundary will still be hanging around the area through Saturday night with the continued threat of showers and storms across the southern sections of the area. .LONG TERM...(Sunday through Friday) Issued at 238 PM CDT Fri Aug 31 2018 An active period is expected with a continued heavy rain threat through much of the week. A large mid/upper ridge will remain anchored across the Mid-Atlantic region with west to southwest flow aloft upstream over the Midwest. Various embedded shortwaves will translate through the flow to produce occasional rounds of showers and storms. The atmosphere will remain conducive to heavy rainfall with precipitable water values exceeding 2.0 inches at times, corresponding to +2 to 3 standard anomalies via the NAEFS. Mesoscale details concerning surface boundary/upper wave placement and consequently convective focus are uncertain, especially given the messy surface pattern and potential contamination from storm outflow. However, the overall pattern certainly suggests a heavy rain/flood threat will continue during this time. Not expecting much change in airmass through the week, with highs in the 70s to low 80s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1152 PM CDT Fri Aug 31 2018 VFR conditions for the moment, but we continue to watch storms developing south of the area into north-central Iowa. Those should continue to fill in the next few hours, but for the moment, it appears LSE/RST will escape much of the action as the best forcing slides by just to our south. With that said, can't rule out some showers and storms working toward those two sites late tonight through Saturday morning, but will have to watch radar trends to ascertain just how far north any convection can survive. Outside of a storm risk, stratus should blossom northward the next few hours (similar to last night), but not sure how widespread it will be. Still, suspect RST will endure at least a few hour period of IFR ceilings, with LSE seeing MVFR. How long those stick around remains tricky, as the lighter wind flow into Saturday afternoon may allow for less mixing out of clouds, but again, will have to see how widespread clouds end up first. Winds will be much lighter into Saturday, generally under 10 knots. && .HYDROLOGY... Issued at 238 PM CDT Fri Aug 31 2018 Will be issuing a flash flood watch for southwest Wisconsin into northeast Iowa for tonight into Saturday. As noted above, as the boundary lifts back north, rapid development of showers and storms expected late this evening as the low level jet impinges on this boundary. The precipitable water values will increase to around 2 inches near the boundary with warm cloud depths of 4 to 4.5 km. Expecting the storms to be very efficient rain producers and included a band of close to two inches of rainfall centered roughly along the Wisconsin River in southwest Wisconsin and expecting that localized amounts will be higher than this. Some of this rain will fall on areas that are already dealing with saturated ground and flooding from the rain earlier in the week and cannot take much more water. For northeast Iowa into Grant County, the ground is not as saturated but terrain is a concern and this area known for mud slides with heavy rain. For now, will include the areas where confidence is highest for a flash flooding threat but the location of the boundary will have to be closely monitored through the evening for possible adjustments to the watch area. Flooding continues along the Kickapoo River, but for the time being, levels are going down. For more details see the latest flood statement. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Flash Flood Watch through Saturday evening for WIZ053>055-061. MN...None. IA...Flash Flood Watch through Saturday evening for IAZ011-030. && SHORT TERM...04 LONG TERM...JM AVIATION...Lawrence HYDROLOGY...04
Hazardous Weather Outlook National Weather Service La Crosse WI 257 PM CDT Fri Aug 31 2018 IAZ008>010-018-019-029-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-012000- Mitchell-Howard-Winneshiek-Floyd-Chickasaw-Fayette-Wabasha-Dodge- Olmsted-Winona-Mower-Fillmore-Houston-Taylor-Clark-Buffalo- Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams- 257 PM CDT Fri Aug 31 2018 This Hazardous Weather Outlook is for portions of north central Iowa...northeast Iowa...southeast Minnesota...central Wisconsin... north central Wisconsin and west central Wisconsin. .DAY ONE...This Afternoon and Tonight Showers and thunderstorms are expected to develop late this evening and continue into the overnight hours, especially along and south of I-90. During the evening some of the storms could become severe, producing damaging wind and large hail. Frequent lightning and heavy rain will be possible with all of the storms. Depending on where it falls, heavy rainfall could lead to localized flash flooding. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Periodic rounds of storms are expected through next week. Additional heavy rain is likely, which could result in more widespread flooding. .SPOTTER INFORMATION STATEMENT... Reports of hail, wind damage, and rainfall amounts are appreciated. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. IAZ011-030-WIZ053>055-061-012000- Allamakee-Clayton-Vernon-Crawford-Richland-Grant- 257 PM CDT Fri Aug 31 2018 This Hazardous Weather Outlook is for portions of northeast Iowa and southwest Wisconsin. .DAY ONE...This Afternoon and Tonight Showers and thunderstorms are expected to develop late this evening and continue into the overnight hours. During the evening some of the storms could become severe, producing damaging wind and large hail. Frequent lightning and heavy rain will be possible with all of the storms. Heavy rainfall could lead to localized flash flooding, especially with the wet ground and already high water levels. A flood watch is in effect through Saturday. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Periodic rounds of storms are expected through next week. Additional heavy rain is likely, which could result in more widespread flooding. .SPOTTER INFORMATION STATEMENT... Reports of hail, wind damage, and rainfall amounts are appreciated. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. DMD
The national radar mosaic for the moment the first event began.
4 flood. Local standard time, as filed.
Flooding along the Lemonweir River in New Lisbon that began in late August, ended in early September.
Flooding along the Kickapoo River at Readstown that began in late August, ended in very early September.
Flooding along the Kickapoo River in Gays Mills began in late August and with another round of heavy rain on September 3rd, continued until the 9th. The river crested over four feet above the flood stage at 17.57 feet on September 6th.
Flooding along the Kickapoo River in Steuben began in late August and with another round of heavy rain on September 3rd, continued until the 11th. The river crested over three feet above the flood stage at 15.41 feet on September 6th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2018Every state in 2018This day in weather historyWarnings in Wisconsin, 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: 785707, 785708, 785887, 785888.