textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Dry and cool conditions through Wednesday. Lows in the low 30s expected tonight and Wednesday night, bringing widespread frost potential. A Frost Advisory is in effect from late tonight through early Wednesday morning for areas away from Lake Michigan.

- Scattered showers with a few snowflakes mixing in Thursday.

- Near normal temperatures late week through this weekend, with readings trending up through next week.

- Periods of on and off showers and storms continue late this week through the middle of next week.

UPDATE

Issued 649 PM CDT Tue May 5 2026

Middle to high clouds will continue to push east northeast across the area tonight, gradually becoming more scattered overnight into Wednesday morning. Gusty west northwest winds should subside by middle evening across the area, with light and variable winds overnight into early Wednesday morning.

Lows tonight should drop into the middle 30s in most areas away from the lake, with some lower 30s in spots. May need to add in Ozaukee and Walworth Counties into the Frost Advisory for later tonight into early Wednesday morning.

Broken diurnal stratocumulus clouds should then develop from middle to late morning Wednesday and linger through the afternoon. There should be west northwest winds developing again by midday lingering into the afternoon, with some gustiness at times. There should also be an east to southeast lake breeze that develops in the afternoon for areas near Lake Michigan. Highs should reach the middle 50s for most areas, with temperatures turning cooler near the lake in the afternoon.

Wood

SHORT TERM

Issued 147 PM CDT Tue May 5 2026

Tonight through Wednesday night:

High diurnal cumulus and dry conditions expected through the rest of the afternoon, with gusty northwest winds at 20-25 mph and highs in the upper 50s to low 60s. Temperatures will drop quickly overnight as skies clear, winds diminish, and low dew points linger across the region. Frost is expected as temperatures drop into the low 30s across inland areas, especially in low-lying areas which may see local temperatures around 30 degrees. A Frost Advisory is in effect for all of southern Wisconsin away from Walworth, Kenosha, Racine, Milwaukee, and Ozaukee Counties. Frost will burn off shortly after sunrise on Wednesday.

Another dry day expected Wednesday as high pressure slides across the area. Winds are expected to remain northwesterly, but less gusty than today. Expecting highs in the mid 50s inland, with highs in the low 50s near Lake Michigan where a weak afternoon lake breeze may develop. High pressure sides southward into the central Plains overnight Wednesday, leading to light winds gradually shifting southwesterly. With light winds and a continuing cold airmass, expecting frost potential away from Lake Michigan once again Wednesday night into Thursday with lows in the low 30s.

Cloud cover increases into Thursday morning as a 500 mb shortwave propagates southeastward through the Upper Midwest. Isolated to scattered showers will develop as this shortwave moves through, with cold enough air aloft to produce a few snowflakes mixing in in the morning. As the shortwave moves through in the afternoon, westerly winds will increase, ushering in a warmer airmass from the Plains and bringing a return to upper 50s and low 60s. Winds become southerly Thursday night, bringing lows in the low 40s to upper 30s. Patchy frost is still possible, but looking less likely as trends toward more southerly flow prevail in the latest modeling.

MH

LONG TERM

Issued 147 PM CDT Tue May 5 2026

Friday through Thursday:

Synopsis: Northwest mid-upper level flow will persist through the duration of the long term, with periodic disturbances & surface frontal passages supporting continued on & off chances for showers and thunderstorms. Northwesterlies aloft will be complemented by predominantly west-northwest low level winds through the weekend, holding temperatures near early-mid May normals. The surface pattern will trend higher in amplitude next week, allowing for more prolonged periods of southwest winds between surface frontal passages over the western Great Lakes. Said winds will allow for temperatures to warm above normal through the middle of next week.

Friday: The first shower & storm chances of the long term period are forecast along an upper shortwave moving in from the Northern Plains. Deterministic & ensemble-based forecasts are in good agreement that the wave will track near or just south of the Wisconsin-Illinois border, placing the best precip potential over the southern ~half of the CWA. Actual precip probs remain in the ~20- 40% range, with values being driven down some by lingering uncertainties regarding the timing of the wave's passage. Anticipate that these values will trend up some over coming forecasts as guidance comes into agreement on precise wave timing. Initial forecast soundings suggest that some weak MUCAPE/thunderstorm potential will be present, with current expectations being for values to be too low to support any strong/severe potential. Will continue to monitor trends through this week.

Saturday into Sunday: The next upper disturbance & surface front arrive over the region, bringing additional chances for showers & storms. Continued a wide (~24 hours) range of chance (~25-45%) precip probabilities in this forecast given remaining uncertainties regarding timing of the wave & frontal passages. Global ensembles are beginning to hone in on Saturday evening/night for favored timing, with a wider envelope of solutions ranging from Saturday afternoon through Sunday morning still apparent in deterministic guidance. Will be refining (& likely increasing) precip probabilities as timing of forcing mechanisms becomes clearer over coming forecasts. Similar to Friday, initial expectations are for available instability to be too low in magnitude to support any strong/severe storms, though trends will continue to be monitored.

Tuesday through Thursday: Passing waves of surface low pressure & cold fronts will support additional periods of showers & storms. Not expecting a complete washout through this time frame, as intermediate areas of high pressure will support periods of dry conditions. Will be watching trends & providing more details as this portion of the period draws closer.

Quigley

AVIATION

Issued 649 PM CDT Tue May 5 2026

Middle to high clouds will continue to push east northeast across the area tonight, gradually becoming more scattered overnight into Wednesday morning. Diurnal stratocumulus clouds around 5000 to 6000 feet AGL should then develop from middle to late morning Wednesday and linger through the afternoon.

Gusty west northwest winds should subside by middle evening across the area, with light and variable winds overnight into early Wednesday morning. There should be west northwest winds developing again by midday lingering into the afternoon, with some gustiness at times. There should also be an east to southeast lake breeze that develops in the afternoon for terminals near Lake Michigan.

Wood

MARINE

Issued 147 PM CDT Tue May 5 2026

High pressure around 29.9 inches continues to slide southward into the central Plains today, bringing light and variable winds to Lake Michigan throughout today and Wednesday. Thursday, weak low pressure around 29.7 inches slides southeastward through Wisconsin, bringing southerly breezes to the Lake. South- southwest winds continue through the end of the week as high pressure remains across the central Plains and multiple weak low pressure systems move eastward through northern Canada. A cold front will turn winds northwesterly Saturday night into Sunday as strong high pressure builds into the western Great Lakes region.

MH

MKX WATCHES/WARNINGS/ADVISORIES

WI...Frost Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057- WIZ058-WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ067-WIZ068- WIZ069...1 AM Wednesday to 8 AM Wednesday.

LM...None.