textproduct: Milwaukee/Sullivan

KEY MESSAGES

- May see some light snow occur into this evening in southwest portions of the area.

- A round of light snow may occur over portions of southern Wisconsin Thursday afternoon and night, with the better chances southwest of Madison. Any accumulations look to remain under one half inch in that area.

- Light snow showers may occur Friday afternoon and evening, with the passage of an Arctic cold front.

- An Arctic airmass is expected this weekend, with wind chills as cold as 15 below to 30 below zero for the overnight and early morning hours.

SHORT TERM

Issued 255 PM CST Wed Dec 10 2025

Tonight through Thursday night:

An area of light snow may clip areas southwest of Madison into this evening, as a sheared vorticity maxima at 500 mb may bring enough differential CVA. It will battle some fairly dry air in the low levels, so not expecting any accumulations or impacts from this system.

There may be some clearing overnight into Thursday morning in northern and eastern portions of the area, as high pressure moves in and subsidence helps erode some of the low clouds. This should allow for lows to drop into the single digits over most of the area, coldest in the clearing areas. Wind chills may get into the single digits below zero.

Middle to high clouds will move back in by Thursday afternoon. An 850 mb low and associated frontogenesis response passing to the southwest of the area later Thursday into Thursday night will bring an area of light snow across Iowa into northern Illinois, with the northern end of this possibly moving across portions of southern Wisconsin. The better chances will again be southwest of Madison Thursday evening. Forecast soundings suggest moisture is modest but sufficient for some light snow.

Ensembles continue to keep just the northern end of this light snow moving across far southern Wisconsin during this period, with the 18Z NAM now backing off in this direction toward the 12Z GFS and ECMWF. Followed this trend in the forecast, with the 60 percent chances just in far southwest parts of the area. Any snow accumulations at this time look to be one half inch or less, mainly southwest of Madison.

Wood

LONG TERM

Issued 245 PM CST Wed Dec 10 2025

Friday through Wednesday:

Will be sitting in a prevailing upper-level northwesterly flow pattern through the end of the week into the weekend. Mid-range models continue to show waves of energy embedded within this pattern and trekking across the region periodically through the weekend. May see some lingering light snow into Friday morning as a shortwave trough works it way east across the Great Lakes, as the surface low lifts up the Ohio River Valley.

Then another lobe of mid-level vorticity begins to work its way down across the Upper Midwest later Friday as the cold air begins to advect down into the region. Could see another round of light snow from this initial lobe. Then the main trough and energy is expected to work its way across Wisconsin into Saturday, but given the increasing subsidence with the building Arctic high, it may limit the potential for additional snow showers.

The main story of this weekend will be the bitter Arctic airmass arriving with the weekend system beginning late Friday night. There is a consistent and persisting signal between the NBM as well as the EPS and GEFS ensembles for single digit high temps Saturday and Sunday, with near zero to sub-zero temps overnight, especially Saturday night into Sunday.

However, with the 1040mb-ish high pressure building down the Upper Mississippi River Valley and low pressure sitting off the East Coast, it will be brisk and there will be higher potential for negative teens to negative 20s wind chills Friday night through Sunday, especially during the overnight hours this weekend. If this trend continues, then could see the first Extreme Cold headlines for the season this weekend.

Fortunately, this bitter cold pattern is looking brief, as the WPC Cluster Analysis supports a 500mb ridge to build into the region for the start of next week. Thus, with the warm air advecting back into the area, trends suggest temps to warm back to near normal by the middle of next week.

Wagner

AVIATION

Issued 255 PM CST Wed Dec 10 2025

An area of light snow may clip areas southwest of Madison into this evening. It will battle some fairly dry air in the low levels, so not expecting any accumulations or impacts from this system.

Ceilings may bounce around between 1000 and 3500 feet AGL into this evening, perhaps more in the 1000 to 2000 foot AGL range by later this evening. There may be some clearing overnight into Thursday morning in northern and eastern portions of the area, as high pressure moves in and subsidence helps erode some of the low ceilings.

Gusty northwest winds are expected to gradually weaken tonight, becoming light and west to southwest on Thursday and light out of the east Thursday night.

Middle to high clouds will move back in by Thursday afternoon. An area of light snow may move across portions of southern Wisconsin later Thursday into Thursday night. The better chances will be southwest of Madison Thursday evening. Any reduced visibility and ceilings should remain southwest of Madison at this time, with snow accumulations generally one half inch or less in this area.

Wood

MARINE

Issued 255 PM CST Wed Dec 10 2025

North to northwest gales will linger until early this evening across the southern two thirds of Lake Michigan. These winds will gradually diminish tonight into Thursday, as high pressure around 30.1 inches moves in from the northwest.

A Small Craft Advisory is in effect for the nearshore waters of Lake Michigan until midnight CST tonight for lingering gusty north to northwest winds and elevated waves.

A period of west to northwest gales may return Friday night into Saturday night, as a strong Arctic cold front moves through the region. Heavy freezing spray may also develop during this period, as the colder airmass moves in. A Small Craft Advisory is likely for the nearshore waters this weekend into early next week as well.

Strong high pressure around 30.8 inches will then move southeast through the region Sunday and to the south early next week. Gusty winds may return early next week.

Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Gale Warning...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671- LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874- LMZ876-LMZ878 until 6 PM Wednesday.

Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until midnight Thursday.