Runoff from snowmelt in late April worked down the Mississippi River and caused some western Wisconsin river flooding to occur in early May.
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.
Runoff from snowmelt in late April worked down the Mississippi River and caused some western Wisconsin river flooding to occur in early May.
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 May 1, 1:36 PM CST, 34 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 236 PM CDT Tue May 1 2018 .SHORT TERM...(This evening through Wednesday) Issued at 236 PM CDT Tue May 1 2018 01.19Z analysis shows a surface cold front from near Duluth to the Twin Cities to Sioux City, IA. This boundary will slowly move eastward, reaching the northwest forecast area by 00Z tonight. Ahead of the front, surface dew points will rise into the mid 50s to lower 60s. Periods of cloud cover so far today have limited heating, thus impacting the amount of available instability, but MUCAPE values from 1000 to 2000 J/kg still seem reasonable by later this afternoon and evening. A thermal cap currently in place will slowly break down from west to east as cooler air moves in with frontal passage, but it may be difficult to tap into the near surface layer given residual warmth from 850 to 700 hPa. A short-wave in southwest flow aloft will act on this environment later this evening. Deep layer shear is strongest behind the front, but do expect an increasing low-level jet after 00Z. This jet will result in strong positive moisture advection into the forecast area. Latest CAMs suggest convection should quickly develop late this afternoon across northeast IA and then become more widespread through the evening and early overnight. Some severe storms will be possible mainly along and south of I-90. Primary threat will be large hail given steep mid-level lapse rates, although some damaging wind is also possible if low-level lapse rates steepen enough to tap into the boundary layer. With PWATS up to 1.5 inches and strong mid-level moisture advection, also concerned about heavy rainfall with 1-3 inches possible across much of northeast IA and southwest WI. Much of this should soak into the topsoil given recent dry conditions, but some runoff and rises on rivers are still possible, especially in areas that see repeated thunderstorms. Additional details are provided in the hydrology section below. Today's cold front hangs up somewhere in the region later tonight into Wednesday and its position will be dependent on the convective evolution this evening. Right now, it appears the front sets-up across the southeast forecast area by 18Z Wednesday, providing a focusing mechanism for additional convection as more short-wave energy moves through southwest flow aloft. While deep layer shear is more favorable for severe storms, the greatest instability is currently forecast to reside just south of the forecast area, limiting the overall severe threat. .LONG TERM...(Wednesday night through Tuesday) Issued at 236 PM CDT Tue May 1 2018 Thunderstorm chances continue Thursday, especially south of I-90 as yet another short-wave moves across the region. Thermodynamic environment looks similar to Wednesday, so severe chances are lower. A stronger northern stream wave finally kicks the warm/moist air mass to the east Thursday night with a return to dry conditions expected Friday into Saturday. New 01.12Z guidance now shows additional shower/thunderstorm chances Saturday night into Sunday, but dry Monday and Tuesday. Warmer temperatures Thursday/Friday with highs in the 70s will cool off a bit for the weekend with highs back in the 60s. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1221 PM CDT Tue May 1 2018 VFR conditions expected to prevail this afternoon, though KRST could see some BKN cigs around 3K ft as the afternoon wears on. Moisture and instability will continue to increase across the area this afternoon into this evening as weak cold front slowly pushes SE across the area. By late this afternoon SHRA/TSRA expected to develop and start spreading east and NE across the area. TSRA, with mainly MVFR cigs/vsbys looking to prevail much of the evening into overnight hours, followed by -SHRA/BR and MVFR/IFR cigs/vsbys. Front to push south of the taf sites late tonight with winds swinging to the NW. These winds to help advect the lower cigs/vsbys out of the area, with VFR vsbys and BKN MVFR cigs expected by later Wed morning. && .HYDROLOGY... Issued at 236 PM CDT Tue May 1 2018 Flood warnings continue along stretches of the Mississippi River. Showers and thunderstorms late this afternoon and evening will produce a broad area of 1-3 inches of rain with the highest amounts generally along and south of I-90. With the ground now fully thawed and little rainfall over the past 10-12 days, much of this rainfall should soak into the topsoil, although could see some runoff and rises on rivers if heavier thunderstorms repeat over the same areas. Additional rounds of rainfall are possible Wednesday and Thursday before drying out to end the week. Not expecting widespread flooding from this rain, but additional rises on area rivers are possible. Please see water.weather.gov for the specific river forecast information. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && SHORT TERM...Rogers LONG TERM...Rogers AVIATION.....RRS HYDROLOGY...Rogers
Hazardous Weather Outlook National Weather Service La Crosse WI 303 PM CDT Tue May 1 2018 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029- 032>034-041>044-053>055-061-022015- 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- 303 PM CDT Tue May 1 2018 This Hazardous Weather Outlook is for portions of southeast Minnesota, northeast Iowa, and southwest into central Wisconsin. .DAY ONE...Late this afternoon and tonight Thunderstorms are expected to develop late this afternoon, then move across the area during the evening and into overnight hours. A few storms may become strong to severe mainly near and south of Interstate 90. The strongest storms will be capable of producing large hail and isolated damaging winds. Rainfall amounts of 1 to 2 inches, locally up to 3 inches, are possible tonight. Some runoff and rises are possible on the tributary streams and rivers. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Thunderstorms are possible at times across much of the area from Wednesday through Thursday night and again Saturday night. At this time, there is a small risk of severe storms south of Interstate 90 on Wednesday afternoon and evening. Water levels will continue to rise along the Mississippi River through the weekend, with minor flooding expected in some areas. Please visit water.weather.gov for the latest river forecast information. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to relay any storm reports this afternoon and evening. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. Boyne/RRS/Rogers
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Runoff from snowmelt in late April worked downstream through the Mississippi River and produced some flooding at La Crosse. The river crested around a quarter of a foot above the flood stage at 12.26 feet on the 4th.
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, May 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: 756994.