Showers and thunderstorms developed ahead of an occluded front Thursday afternoon (5/15) across western Wisconsin. Storms tracked through the area during the late afternoon and early evening hours.
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 GRB wrote it up.
Showers and thunderstorms developed ahead of an occluded front Thursday afternoon (5/15) across western Wisconsin. Storms tracked through the area during the late afternoon and early evening hours. The strongest storms produced 3 tornadoes, damaging winds, and large hail up to golf ball size across central and north-central Wisconsin.
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 Green Bay, WI wrote its last area forecast discussion before the first event at May 15, 3:00 PM CST, 37 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Green Bay WI
Issued by National Weather Service Milwaukee/Sullivan WI
400 PM CDT Thu May 15 2025
.KEY MESSAGES...
- Marine Dense Fog Advisory for the nearshore areas of Lake
Michigan through the early evening. A Small Craft Advisory
- A broken line of strong thunderstorms will cross northern WI
between 4 and 9 PM today. Some severe storms are likely with
the passage of a cold front. All hazards possible over central
WI and large hail possible over eastern WI.
- Another period of showers and weak storms expected Friday with
some potential for gusty winds with some of these
showers/storms.
&&
.DISCUSSION...
Issued at 304 PM CDT Thu May 15 2025
The Rest of this Afternoon through Friday Night:
A broken line of cellular storms has broken out, currently from
Eau Claire down to Madison WI. This is line is expected to
develop further and ramp up in intensity this evening. Hail and
gusty winds are expected, owing to SBCAPE around 2500 J/kg amid
effective shear around 40 knots. A couple tornadoes also look
possible, given effective SRH values around 200 m2/s2 over much
of NE WI, and an effective warm front parked from the Fox
Valley up through Marathon and Lincoln County. The peak timing
for storms looks to be from 5pm through 8pm this evening as the
broken line moves northeast. A Tornado Watch is out from now
through 10pm over much of our CWA.
Storms will quickly move through and a dry punch aloft will
clear out skies fairly quickly behind the storms. There will be
a bit of a lull overnight, but tomorrow, enhanced mixing will
lead to gusty southwest winds with some scattered gusts to 40
mph. A secondary shortwave pivoting around an upper level low
and lingering moisture will squeeze out some more scattered
thunderstorm activity in the afternoon. Very dry low levels and
the high based nature of the storms will cause the potential for
gusty winds with any storms that get established enough in the
environment.
Saturday through Wednesday
The upper low will linger into Saturday. Cooler conditions are
expected due to clouds and the cooler air aloft and highs will
top out in the low to mid 60. Diurnally driven scattered
showers may occur through the day. This upper low should move
east on Sunday, restoring relative high pressure, but clouds
will likely linger along with cooler temperatures as winds will
come around to northeasterly. By late in the extended period, a
large low pressure system is expected to approach the upper
Midwest Monday into Tuesday, bringing a prolonged period of
showery rain and clouds to the area. Winds will remain
northeasterly off of the lake, keeping our CWA cool with highs
in the 50s.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 304 PM CDT Thu May 15 2025
Current conditions still largely remain VFR across the CWA with
SCT to CLR conditions most everywhere save for areas from west
of KGRB to KCWA where BKN040 is largely present. A line of
storms currently present, arching from KMSN to KMSP, and this
line should continue to develop and move northeast between now
and 03z this evening. These storms will feature gusty winds, and
large hail. Following storms, skies are expected to remain
clear overnight as a dry slot moves in, with mostly clear winds.
VFR ceilings return tomorrow afternoon with sfc wind gusts
becoming strong out of the southwest to 35 knots in spots. There
may be additional scattered thunderstorm development in the
afternoon with gusty winds being the primary threat.
&&
.MARINE...
Issued at 304 PM CDT Thu May 15 2025
Marine dense fog will continue into this evening until
thunderstorms and a front pass during the early evening hours. A
small craft advisory will also continue into tonight on
southeast winds. Following the passage of the front, winds
should ease for a time overnight and then come around to
southwesterly by tomorrow at dawn. Gusty southwesterly winds are
then expected to pick up leading to a potential second period of
Small Craft Advisory conditions during tomorrow afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...Dense Fog Advisory until 7 PM CDT this evening for LMZ521-522-
541>543.
Small Craft Advisory until 1 AM CDT Friday for LMZ522.
Small Craft Advisory until 11 PM CDT this evening for LMZ542-
543.
&&
DISCUSSION...
AVIATION...
MARINE...Hazardous Weather Outlook National Weather Service Green Bay WI Issued by National Weather Service Milwaukee/Sullivan WI 308 PM CDT Thu May 15 2025 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-162015- Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln- Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano- Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago- Calumet-Manitowoc-Southern Marinette County- Southern Oconto County- 308 PM CDT Thu May 15 2025 This Hazardous Weather Outlook is for north-central and northeast Wisconsin. .DAY ONE...Tonight A line of strong thunderstorms will cross northern WI between 4 and 9 PM this afternoon into tonight. Severe storms are likely with all hazards possible over central WI and large hail possible over eastern WI. .DAYS TWO THROUGH SEVEN...Friday through Thursday Gusty southwest winds up to 45 mph are possible for the Fox Valley on Friday. Showers and another round of storms may bring gusty winds Friday afternoon. Thunderstorms may return Tuesday into Wednesday of next week. .SPOTTER INFORMATION STATEMENT... Spotter activation will be needed this afternoon and evening. Your reports are appreciated. LMZ521-522-541>543-162015- The Bay of Green Bay south of a line from Cedar River MI to Rock Island Passage-Lake Michigan from Washington Island to Sheboygan- 308 PM CDT Thu May 15 2025 This Hazardous Weather Outlook is for portions of northwest Lake Michigan and the waters of Green Bay. .DAY ONE...Tonight A Marine Dense Fog Advisory remains in effect through the early evening. Small Craft Advisory in effect this afternoon through much of the evening for the southern portion of the Bay of Green Bay as well as in the nearshore from Sturgeon Bay to Sheboygan. Thunderstorms are expected this afternoon and evening. Some of the storms could become severe. The primary hazard will be large hail. .DAYS TWO THROUGH SEVEN...Friday through Thursday Hazardous conditions for small craft are possible Friday through Saturday due to high winds, particularly for Lake Michigan nearshore waters.
The La Crosse radar (KARX), 126 km away, was scanning. The volume nearest the first event began at 21:34 UTC.
7 hail, 3 tornado, 2 thunderstorm wind. Local standard time, as filed.
Quarter size hail fell in Wisconsin Rapids. The time of this report is an estimate based on radar data.
A tornado developed in fields west of Unity in Clark County (NWS La Crosse warning area) at 5:21 pm CDT before tracking northeast toward Colby. The tornado moved through rural areas of northeastern Clark County, damaging multiple farm outbuildings, trees, power poles, and a home before crossing Highway 13 into western Marathon County at 5:27 pm CDT. The tornado tracked through the southeastern edge of Colby damaging another home, multiple outbuildings, power poles, and a car dealership before dissipating at 5:28 pm CDT. Total path length is estimated to be 4.81 miles long, with a width of 230 yards. Peak wind estimated to be around 120 mph.
A tornado developed near Rib Falls at 5:41 pm CDT, then tracked north before lifting at 5:50 pm CDT. Most of the tornado occurred over an area that was void of clear damage indicators. Total path length is estimated to be 2.50 miles long, with a width of 65 yards. Peak wind estimated to be around 85 mph.
A tornado developed near Bancroft at 5:52 pm CDT, then tracked north before lifting at 6:03 pm CDT. The start of the tornado was noted by trees across a road near the start of the path, with the rest of the tornado occurring over open area that was void of clear damage indicators. Total path length is estimated to be 5.21 miles long, with a width of 45 yards. Peak wind estimated to be around 65 mph.
Ping pong size hail fell near Bancroft.
Golf ball size hail fell near Weston.
Quarter size hail fell near Evergreen.
Half dollar size hail fell near Evergreen.
Thunderstorm winds caused roof damage near Merrill. The time of this report is an estimate based on radar data.
Quarter size hail fell near Wausau.
Thunderstorm winds downed trees near Harshaw. The time of this report is an estimate based on radar data.
Ping pong size hail fell near Amherst Junction.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2025Every state in 2025This day in weather historyThe tornado archive for Wisconsin, 2025Warnings in Wisconsin, May 2025
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: 1247782, 1247794, 1247791, 1247792, 1247783, 1247784, 1247785, 1247786, 1247789, 1247787, 1247790, 1247788.