textproduct: Milwaukee/Sullivan

KEY MESSAGES

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

- Widespread showers (80 to 100 percent chances) and scattered thunderstorms are expected during the late afternoon and early evening. Severe gusts are possible.

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

SHORT TERM

Issued 114 AM CDT Mon Apr 27 2026

Overnight through Monday Night:

Fog and low stratus along lakeshore visited the Milwaukee area temporarily in the evening, but it dissipated.

A broad upper trough is set up over the center of the country with several embedded shortwaves tonight. One area of interest is the widespread rain over eastern SD and southern MN (with some clearing in IA). This is associated with the leading shortwave trough, warm air advection, and the nose of a low level jet. This is also where a weak surface low is identified in northwest IA per the wind field. Another area is over eastern MO where severe storms are ongoing and are expected to track ESE overnight (no threat to WI). The other area is over western KS where convection is ongoing and is associated with a strong shortwave trough, the nose of a very strong low level jet, and a surface warm front. There is also a surface low with this feature (deeper than the IA one) but it is going to lift toward the IA/MN low and occlude.

These KS storms are the ones that could affect the WI weather in the morning. The storms are expected to evolve into a broken line of storms as they track across northern MO and IA overnight. Weakening showers and a few storms might make it into southern WI between 10 am and 2 pm. There is no severe risk for southern WI during this time.

Meanwhile, a few showers with a mid level shortwave trough and the nose of a LLJ may track across southern WI during the morning hours between 5 and 8 am. There is light reflectivity on radar but only sprinkles are reaching the ground.

A lull in the precip over southern WI is still looking likely from roughly noon to 4pm. If we can get sunshine during this time, it will help increase the instability to support stronger storms for the potential evening round.

Our attention turns to storms that are expected to develop along the cold front pushing into MO and eastern IA during the late afternoon. Given the high-shear environment, lines of storms are anticipated. Storm motion will be to the northeast, so the MO storms should track into northern and central IL. Many of the 00z models keep the majority of these storms just to the south of the WI/IL border. Therefore, the enhanced risk was trimmed out of southern WI and northern IL since the worst of it is aiming at central and southern IL. The anticipated eastern IA convection, firing just ahead of the cold front and supported by cyclogenesis over MN from the digging upper trough and a strong low level jet, has the potential to keep storm development going as they track through southern WI as long as there was enough instability built up from any afternoon sun.

If strong storms develop, they could produce damaging winds (and brief small hail). Given the strong 0-3km shear, any little bowing line segment would be suspect for a line-embedded tornado. There is still a slight risk for severe over most of southern WI to account for a few severe storms possible during the early evening hours. The heavy rain potential is still there, but trending down. The storms are still expected to clear southeast WI around midnight with the passage of the cold front.

Cronce

LONG TERM

Issued 114 AM CDT Mon Apr 27 2026

Tuesday through Sunday:

Cold air advection on gusty west winds should move into the area Tuesday, which should start to bring cooler and drier air. Temperatures should cool down to near normal or a little below normal values into the rest of the week, as 500 mb cluster analysis shows an anomalous and elongated low/trough shifting slowly east across the region. There may be some frost that occurs Wednesday night, Thursday night and Friday night, depending on if winds can become light enough within this cooler airmass.

There may be small chances (around 20 percent) for light rain showers Thursday, as a shortwave trough shifts through the area with modest moisture. Otherwise, the rest of the week looks fairly dry, with high pressure passing to the southwest of the area.

Ensemble means suggest another high may move southeast through the area Friday into Saturday, with temperatures possibly rising a bit per ensemble mean trends. It looks more uncertain toward Sunday, as some chances for precipitation (around 20 to 30 percent) may return to the area.

Wood

AVIATION

Issued 114 AM CDT Mon Apr 27 2026

IFR stratus and light fog briefly hit MKE but have since dissipated. There is a chance that they could return due to the easterly winds and moist air off the lake, but not enough confidence to include it in the TAF at this time. MVFR ceilings are expected to develop over southern WI during the late morning as a weak wave and dissipating convection passes across the area during mid-late morning. A lull in the precip is still looking likely between 18 and 21Z today. With a strong south wind just above the surface and steady southeast winds at the surface, LLWS is included in the TAFs for most of the day.

An area of showers and thunderstorms will likely track across southern WI between 21Z and 02Z today as a cold front approaches. A few severe gusts are possible. Gusty west winds will develop overnight, but especially Tuesday morning, in the wake of the cold front.

Cronce

MARINE

Issued 114 AM CDT Mon Apr 27 2026

Low pressure of 29.4 inches is expected to lift from northeast Kansas tonight to Lake Superior by later Monday night while deepening to 29.3 inches. Look for increasing easterly winds tonight and southeast winds through Monday night as the low approaches. The cooler lake temps should dampen the threat for gales across the lake. Winds will shift to the west early Tuesday morning with the cold frontal passage, and gusty westerly winds are expected through Tuesday afternoon behind the departing low.

High pressure around 30.1 inches will set up over the Upper Midwest and Upper Great Lakes Tuesday through Friday.

A Small Craft Advisory is in effect for the nearshore areas from early Monday morning for the persistent southeast winds, and until Tuesday afternoon when the gusty westerly winds diminish behind the front.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

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