textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Some fog and low stratus clouds may develop in eastern parts of the area this evening and may linger overnight.

- Widespread showers (80 to 100 percent chances) and scattered thunderstorms return for Monday into Monday night. There is the potential for severe weather Monday afternoon and evening, with locally heavy rainfall also possible.

- Cooler temps Tuesday through the end of next week, with a frost/freeze potential by the end of the week.

UPDATE

Issued 636 PM CDT Sun Apr 26 2026

Some fog and low stratus clouds may develop in eastern parts of the area this evening, as moist low level flow off of Lake Michigan continues. There are varying model solutions with the flog and low clouds this evening and overnight, but there seems to be enough of them showing this development to have them in the forecast at least through this evening. Confidence is low with how long this may last if it develops. Will watch trends and adjust the forecast as needed.

Wood

SHORT TERM

Issued 217 PM CDT Sun Apr 26 2026

Tonight through Monday night:

Aside from lingering clouds near the lake, skies should start out mostly clear this evening, with increasing mid and high level clouds overnight as warm advection aloft increases ahead of an approaching low. Showers and a few storms associated with the strong warm advection will reach the southwest forecast area by or shortly after daybreak. This area will lift through southwest to northeast through the morning hours, exiting the east by early afternoon. Only marginal instability with this round of precip, so severe storms are not expected through the morning.

There should be a lull in precip during the early to mid- afternoon hours tomorrow. This may allow for a period of time for temps to warm up a bit under southeast winds, as surface low pressure lifts from central Iowa into west-central Wisconsin. Not expecting to see the sun much at all, but filtered sunshine through lingering mid/high level clouds may be enough for temps to rise into the mid/upper 60s, providing some destabilization for the next round of storms.

By late afternoon, the more solidly defined warm sector based on temps from the sfc to 925 mb is expected to start to lift into the forecast area from the southwest, sliding through the southern half of the forecast area during the late afternoon and evening hours. Confidence has increased in a window of modest surface based instability during this time frame ahead of the approaching cold front. Given a strong LLJ overhead and plenty of shear, it's looking more probable that an organized line of storms will push through areas mainly south of I-94 during the late afternoon and evening. Though some hail is not out of the question, this setup is trending towards a damaging wind and QLCS tornado threat if severe storms develop. The peak window of opportunity for severe storms tomorrow should be from 5 to 10 pm, with the storms departing to the east late in the evening.

Will continue to keep an eye on a heavy rainfall threat as well tomorrow, given models push the ~1.50" precipitable water values into southern portions of the forecast area. Localized flooding would be a concern given saturated soils and rivers remaining elevated.

DDV

LONG TERM

Issued 217 PM CDT Sun Apr 26 2026

Tuesday through Sunday:

Northwest flow will develop Tuesday behind the departing low and will likely persist through the remainder of the week and into the weekend. Surface high pressure will bring quiet weather much of this time, though a shortwave or two may bring some light rain chances at times. Temps in this pattern will run near to a few degrees below normal through at least late week. Could see a return of a frost/freeze potential the second half of the week.

DDV

AVIATION

Issued 636 PM CDT Sun Apr 26 2026

Some fog with 1 to 3 mile visibility and low stratus clouds around 300 feet AGL may develop in eastern parts of the area this evening, as moist low level flow off of Lake Michigan continues. There are varying model solutions with the fog and low clouds this evening and overnight, but there seems to be enough of them showing this development to have them in the forecast at least through this evening for Milwaukee and Kenosha. Confidence is low with how long this may last if it develops. Will watch trends and adjust the forecast as needed.

Low level wind shear conditions are expected for Sheboygan, Waukesha, Milwaukee and Kenosha from around 15Z Monday through Monday evening. 2000 foot AGL winds should be southeast to south around 40 knots around 15Z Monday and increase to up to 60 knots by around 18Z Monday. Surface winds should increase from the southeast to south and become gusty by middle morning Monday and linger into Monday evening.

A period of showers and some storms should move through the area Monday morning, mainly from around 12Z to 18Z Monday. There should be a lull in the activity, before a round of stronger storms moves through between 22Z Monday and 05Z Tuesday. May see a line of storms with strong winds during this period, with areas mainly along and south of Madison to Milwaukee having the better chances to see this activity. Ceilings should drop into the 1000 to 1500 foot AGL range with the second round of storms, with lower values at times. Visibility may be limited to 1 to 3 miles or less as well at times within storms.

Wood

MARINE

Issued 636 PM CDT Sun Apr 26 2026

There may be some fog that lingers into this evening across central portions of Lake Michigan, as moist air there lingers. More fog may develop this evening into the overnight hours along the western shore of the lake, but this is uncertain and will be monitored.

East to northeast winds of 5 to 10 knots will continue into the evening hours today. Low pressure of 29.4 inches is expected to lift from northeast Kansas early Monday to Lake Superior by later Monday night. Winds will become east to southeast tonight ahead of the low, increasing to around 10-15 knots. Winds will then increase Monday into Monday night out of the south to southeast as the low approaches. The cooler lake temps should dampen the threat for gales across the lake, with Small Craft Advisory conditions likely for the nearshore waters. Breezy westerly winds are expected Tuesday behind the departing low.

DDV/Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...4 AM Monday to 1 PM Tuesday.