textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Strong to severe thunderstorms expected this evening, with all hazards possible. An Enhanced Risk for severe is outlooked by SPC. A Tornado Watch is in effect until 8 PM CDT for much of southern WI.

- Additional chances for rain and strong thunderstorms Friday evening into Saturday.

- Gales will continue over Lake MI into this evening.

UPDATE

Issued 530 PM CDT Thu Apr 2 2026

Storms have developed across the Mississippi Valley this evening, and are already producing tornadoes, golf ball sized hail, and damaging winds. Strong surface WAA is building into far southern Wisconsin ahead of these storms, priming our environment for similar activity within the next hour. Temperatures have already quickly risen into the mid-60s across the farthest southern line of Wisconsin counties, with expectation that the warm front with similar temperatures will continue to push north through Dane, Dodge, Washington, and Ozaukee Counties within the next two hours. Low track into Fond du Lac and Sheboygan Counties on both meso models and high res guidance indicates potential for storm development/warm frontal boundary convection all the way through those regions. With that, have expanded the Tornado Watch to include all counties south and east of Iowa/Dane/Columbia/Fond du Lac.

Mixed Layer CAPE values of 750-1000 J/kg expected through the I-94 corridor (supercellular mode possible with any cells that develop ahead of the main line), with values 500-750 expected north of the corridor (transition to a QLCS as instability decreases). Southwesterly bulk shear of 50-60 kt will allow for any surges to the northeast to become capable of breaking through any remaining capping inversion north of I-94, and producing damaging winds and perhaps a few tornadoes. Tornado Watch currently out through 8 PM CDT, but may need an extension for an hour or two for the northeasternmost counties in the Watch.

MH

SHORT TERM

Issued 351 PM CDT Thu Apr 2 2026

Tonight through Friday night:

Currently, all of southern WI is parked just north of a warm front that is expected to surge north through the rest of the afternoon and early evening. This will happen as a surface low rapidly tracks from central Iowa to southwest Wisconsin by this evening. Showery rain and fog should lift north and give way to warmer temperatures, with some brief clearing over southwest WI as the warm sector moves in. With daytime solar insolation and strong warm advection, temperatures and dewpoints in the 60s should be realized late afternoon into this evening and MLCAPE is expected to rise to around 1100 J/kg along the WI/IL border. Looking at radar trends to our west, a scattering of low-topped supercells and QLCS line segments will be the mode this evening. Given great low level SRH around 200 m2/s2 and sickle shaped hodographs in the low levels, tornadoes will be possible with any well established supercells and QLCS-line segments. Damaging wind will also be possible where low level instability is maximized and large hail can't be ruled out with any supercells.

At this time, the highest severe threat appears to be along the WI/IL border where the best surface-based environment will be realized. A Tornado Watch has been issued for Lafayette, Green, Rock, and Walworth Counties until 8pm. Areas north toward I-94 are not out of the woods, as even with a more marginal CAPE environment, most CAPE will be in the 0-3km layer supporting a more marginal wind and tor threat. Storms are expected to move in around 5 and move out over Lake Michigan around 11pm.

Following tonight's excitement a brief surface ridge is expected to move through Friday, before a surface low approaches for Friday night into Saturday. Another more marginal round of strong to severe weather may occur, primarily south and west of Madison as a line of storms form along an occluded front. Lapse rates will be a bit better amid 1000 to 1500 J/kg of MUCAPE, but storms will primarily be elevated, leading to a hail threat. Storms will then move through Friday night, generally weakening as they head east toward Lake Michigan, and exiting through dawn on Saturday.

CMiller

LONG TERM

Issued 351 PM CDT Thu Apr 2 2026

Saturday through Thursday:

The occluded low and front will pass Sat AM with much of the widespread showers and storms already to the east, but scattered showers may linger. The broad occluded low will then gradually deepen as it lifts newd into the nrn Great Lakes later on Sat, then to wrn Quebec by 12Z Sun. Brisk wnwly winds and cold advection will prevail Sat afternoon into Sun with high temps from 45-50F for Sunday. The cool conditions will continue through Tue as a couple shortwave troughs in nwly flow aloft reinforce the cool air mass. They will also bring 20 percent chances for light rain and snow Sun nt-Mon. Large high pressure will then shift across srn WI on Tue, moving to the Mid Atlantic States on Wed. Sly winds and warm, moist advection will then boost temps for Wed, but also bring 20 to 30 percent chances for rain. A weakening Canadian cold front may then stall over the region Wed nt-Thu with 40-50 percent chances of rain.

Gehring

AVIATION

Issued 530 PM CDT Thu Apr 2 2026

Afternoon round of showers and storms are lifting to the northeast and the warm front is gradually lifting northward. May see an hour or two window in between the departing activity and redevelopment with improving flight conditions. Otherwise, expecting the showers and storms to redevelop through the evening as low pressure lifts northeastward from IA through southern WI. Will see a broken line of strong to severe thunderstorms with this activity now through 04z. With any strong to severe thunderstorm activity can see lower LIFR/IFR ceiling and visibilities along with heavy rain, damaging winds, large hail, and even a few tornadoes at times. Severe chances work southwest to northeast through the evening and reaching the lakeshore by 04z. Will see this activity wind down as the low and cold front pushes through, lower ceilings may linger with a westerly wind shift overnight. Winds then ease and turn more easterly into Friday.

Wagner

MARINE

Issued 351 PM CDT Thu Apr 2 2026

Gusty easterly winds over the north end of Lake Michigan and southerly winds of the southern two thirds are currently ongoing as a low pressure of 29.4 inches approaches from southern Iowa. This low will pass over the midsection of the lake tonight, ending the gales over the northern end of the lake, while southerly gales will continue south until a cold front sweeps through.

Winds will then become northwesterly tonight and then light and variable for a time midday Friday as a weak surface ridge passes over the lake.

Winds will then become northeasterly Friday night as a weaker low pressure of 29.8 inches occludes and passes over the southern end of the lake through early Saturday. Easterly winds over the northern end of the lake may reach gale force Saturday morning. Winds then veer southwesterly through Saturday following the surface low.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ563 until 9 PM Thursday.

Gale Warning...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671- LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874- LMZ876-LMZ878 until 1 AM Friday.

Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 4 AM Friday.