Two rounds of thunderstorms moved across western Wisconsin on May 15th. The first formed in the afternoon and dropped some dime sized hail across portions of Juneau County.
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.
Two rounds of thunderstorms moved across western Wisconsin on May 15th. The first formed in the afternoon and dropped some dime sized hail across portions of Juneau County. A lightning strike from this first round of storms ignited a fire at a care facility in Holmen (La Crosse County). The second round moved across Grant County during the evening hours with 60 to 65 mph winds and some dime sized hail. A 68 mph wind gust occurred in Cuba City. The winds damaged roofs on a church in Tennyson and a school in Cuba City.
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 15, 11:24 AM CST, 1 hour 6 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 1224 PM CDT Mon May 15 2017 .SHORT TERM...(Today through Wednesday Night) Issued at 300 AM CDT Mon May 15 2017 High Impact Weather Potential: Several rounds of showers and thunderstorms appear increasingly likely today through Wednesday evening. While some uncertainty remains with regard to overall coverage and placement of storms during any particular period, some risk for severe storms appears possible this afternoon and tonight, and again on Wednesday, with a low end risk for maybe some heavy rainfall tonight as well. Weekend's over, and lots to look at as we head through the first half of the new work week. Early morning analysis places pronounced mid level ridging directly overhead early this morning, ahead of deeper western CONUS troughing, with a notable upper wave digging southward off the California coast (our system for Wednesday). At the surface, a stationary boundary is laid out just west of the Mississippi River as of 06Z, tied to a remnant weak lee cyclone over southwest Minnesota, with that feature expected to gradually redevelop into a warm front somewhere over central Iowa this afternoon as stronger height falls over the central High Plains aid in redevelopment of lee cyclogenesis over eastern Colorado. It is that boundary and the interaction of increasing moisture and low level jet forcing that will have a big impact on convective evolution over our area through early Tuesday morning, and while details are becoming a little more clear, there do remain plenty of forecast challenges regarding the eventual evolution of any storms. Current westward expansion of much drier air early this morning will be replaced by building boundary layer dew points back through the 50s to probably lower 60s through midday and beyond - a trend well agreed upon by guidance the past 24 hours. While the true surface warm front may mix toward northern Iowa for a time later today (exact position TBD), it appears ongoing convection across western South Dakota will continue to march eastward, probably redeveloping to some degree as it encounters increasing moisture transport into the local area. Much of the activity up this way will remain elevated, but will have to watch where the surface front ends up, as a low end severe threat for bowing segments could exist south of the boundary with just enough shear and building instability to around 1800 J/kg. The next window for more widespread convection still looks to be tonight with strong low/mid level moisture transport on the nose of a 40-50 knot jet working north across the area. Robust warm advection will also help increase instability, with elevated CAPE values around 2000 J/kg per forecast RAOBs in an increasingly sheared environment. Given the setup, can't rule out some elevated hail-producing storms, though higher freezing levels up around 13kft may mitigate that threat to some degree. In addition, can't totally rule out some heavy rain threat with the low level warm front likely to get hung up for a time as convection develops, though with such strong low level flow developing, have to believe that boundary will eventually get lifted north before 12Z into central Wisconsin. As such, while PWAT values do peak around 1.5 inches (2 SD above normal), heavy rains may end up being rather transient. Still looking like much of the area gets strongly capped off on Tuesday, of course provided that the warm front actually does lift north. That setups up a fairly "clean" warm sector with deeper mechanical mixing of stronger flow aloft likely to bring both a windy day (gusts 30-35 knots very much possible) but also a very warm one, with highs well into the 80s to perhaps even near 90 in a few spots as 925 mb temps peak at 22-25C. What happens thereafter later Tuesday night into Wednesday in terms of additional convection remains heavily in question, though there are some signals for a linear convective line to work east out of western Minnesota, perhaps diminishing as it approaches our northern areas given stronger capping in place. However, approach of a robust negative tilt shortwave and associated difluence aloft on Wednesday should lead us toward additional convective development, though just how all that play out, and how clean the Wednesday environment is, remains low confidence. However, with increasing low and deep layer shear profiles, a risk for severe storms will certainly exist. .LONG TERM...(Thursday through Sunday) Issued at 300 AM CDT Mon May 15 2017 The active stretch of weather looks to continue through next weekend, along with a trend toward cooling temperatures, as the deeper western CONUS trough gradually works east through our region. As discussed in recent days, much of Thursday continues to look dry, along with maybe part of Friday as well, with expansive low level ridging and dry air building south from the northern Plains and Great Lakes. However, the slow approach of the upper trough and return to deeper moisture and forcing should bring a few bouts of rain back to the area later Friday right on through the weekend, with the overall threat for thunder at this point looking quite low as all instability remains tucked well to our south. Instead, low level northerly to northeasterly flow and shallow cool air coupled with clouds and periods of rain should act to bring temps below normal, with the distinct possibility that some spots could see highs only in the 50s a day or two, pending the evolution and timing of rainfall. Soak in all that warmth the next few days! && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1224 PM CDT Mon May 15 2017 VFR conditions will give way to periods of showers and thunderstorms this afternoon at both KRST/KLSE. Ceilings and visibility could drop to MVFR (possibly IFR) in the strongest storms with gusty erratic winds. For now, will cover thunder threat using TEMPO groups with the best time estimates from 20-23Z at KRST and from 21-24Z at KLSE, although adjustments will be likely as storms move across the area. A second round of showers and thunderstorms are possible later this evening and overnight, but their timing, coverage, and severity will be highly dependent on what happens this afternoon. For now, kept TAFs dry later this evening until better certainty emerges. Winds away from thunderstorms will be light, generally from the south-southeast through most of the period. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && SHORT TERM...Lawrence LONG TERM....Lawrence AVIATION...Rogers
Hazardous Weather Outlook National Weather Service La Crosse WI 1033 AM CDT Mon May 15 2017 IAZ008>011-018-019-029-030-MNZ094>096-WIZ053>055-061-161545- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Mower-Fillmore-Houston-Vernon-Crawford-Richland-Grant- 1033 AM CDT Mon May 15 2017 This Hazardous Weather Outlook is for portions of north central Iowa...northeast Iowa...southeast Minnesota and southwest Wisconsin. .DAY ONE...Today and Tonight Strong to severe thunderstorms are expected this afternoon between 2 pm and 6 pm for areas south of Interstate 90. Large hail and damaging winds will be the primary threats. A second round of thunderstorms are expected later this evening and tonight, with the greatest risks being large hail and locally heavy rainfall. During the evening hours, however, damaging winds and an isolated tornado cannot be ruled out near a warm front across northern Iowa into southern Wisconsin. There is still some uncertainty concerning the timing, placement, and severity of any thunderstorms later this evening and tonight as details will be dependent on thunderstorm evolution this afternoon. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional chances for thunderstorms will exist Tuesday morning and again Tuesday night through Wednesday evening. A few storms on Wednesday could pose a risk for severe weather. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon between 2 pm and 6 pm for areas south of Interstate 90. Spotters could be needed again later this evening and tonight. Reports of severe weather are appreciated through tonight. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. MNZ079-086>088-WIZ017-029-032>034-041>044-161545- Wabasha-Dodge-Olmsted-Winona-Taylor-Clark-Buffalo-Trempealeau- Jackson-La Crosse-Monroe-Juneau-Adams- 1033 AM CDT Mon May 15 2017 This Hazardous Weather Outlook is for portions of southeast Minnesota...central Wisconsin...north central Wisconsin and west central Wisconsin. .DAY ONE...Today and Tonight A few strong to severe thunderstorms are possible this afternoon between 2 pm and 6 pm for areas along and north of Interstate 90. Isolated large hail is the primary threat. A second round of thunderstorms are expected later this evening and tonight, with the greatest risks being large hail and locally heavy rainfall. There is still some uncertainty concerning the timing, placement, and severity of any thunderstorms later this evening and tonight as details will be dependent on thunderstorm evolution this afternoon. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional chances for thunderstorms will exist Tuesday morning and again Tuesday night through Wednesday evening. A few storms on Wednesday could pose a risk for severe weather. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected this afternoon and evening for areas along and north of Interstate 90, but severe weather reports are still appreciated. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. Rogers
Special Weather Statement
National Weather Service La Crosse WI
1222 PM CDT MON MAY 15 2017
MNZ079-086-087-151815-
Wabasha-Olmsted-Dodge-
1222 PM CDT MON MAY 15 2017
...Thunderstorms are moving across parts of southeast Minnesota...
A cluster of thunderstorms, with lightning, heavy rain, and a small
hail risk, was moving across parts of southeast Minnesota, including
communities west and north of the Rochester area.
If you are outdoors early this afternoon, remain alert for
approaching storms and the lightning risk.
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.
Additional stronger storms are expected later in the afternoon that
could produce more widespread severe weather. Be weather aware today.
LAT...LON 4420 9304 4419 9255 4437 9255 4437 9243
4445 9243 4445 9224 4440 9205 4433 9192
4429 9193 4427 9190 4423 9189 4420 9186
4419 9208 4385 9208 4385 9245 4383 9245
4383 9269 4385 9269 4385 9305
TIME...MOT...LOC 1719Z 239DEG 32KT 4417 9299
SheaSpecial Weather Statement
National Weather Service La Crosse WI
119 PM CDT MON MAY 15 2017
MNZ079-WIZ032-033-151845-
Wabasha-Buffalo-Trempealeau-
119 PM CDT MON MAY 15 2017
...Thunderstorms crossing into Western Wisconsin...
At 117 PM, radar indicated a line of thunderstorms with heavy rain,
lightning, and small hail over Wabasha County Minnesota. These
storms will be crossing the Mississippi River and into Wisconsin by
2pm.
Pea size hail is possible with these storms. Lightning is also a
risk so move indoors as the storms pass.
If you are on the Mississippi River near and south of Lake
Pepin...move to shore.
LAT...LON 4445 9243 4445 9224 4444 9221 4441 9208
4451 9204 4456 9204 4459 9202 4459 9120
4433 9134 4419 9207 4440 9243
TIME...MOT...LOC 1817Z 247DEG 24KT 4446 9241 4426 9207
SheaThe La Crosse radar (KARX), 18 km away, was scanning. The volume nearest the first event began at 18:28 UTC.
8 thunderstorm wind, 5 hail, 1 lightning. Local standard time, as filed.
A fire at a care facility in Holmen was started by a lightning strike. The fire was trapped between the ceiling and roof with the building sustaining substantial water and fire damage. All the residents of the care facility were safely evacuated.
Trees were blown down in Cassville from an estimated 60 mph wind gust.
An estimated 65 mph wind gust occurred in Potosi. Trees were blown down and windows shattered by the winds. Some of the trees landed on houses and several campers in a campground were also damaged.
The roof of a church was damaged in Tennyson.
Debris was blown across a highway southeast of Lancaster.
A wind gust of 68 mph occurred in Cuba City. The roof of a private school was blown off by the winds.
A semitrailer was tipped over in Platteville.
An estimated 60 mph wind gust occurred in Montfort.
An estimated 60 mph wind gust blew down small tree branches in Hazel Green.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2017Every state in 2017This day in weather historyWarnings in Wisconsin, May 2017
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: 702166, 691857, 691858, 697263, 697269, 697403, 702238, 697404, 697405, 702234, 697406, 697407, 697408, 697428.