textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Temperatures continue to trend well above normal through the end of the week.

- Chances (about 30 to 50 percent) for light rain or drizzle in southeast Wisconsin Wednesday evening, with rain likely (about 50 to 70 percent chances) area wide Christmas night.

UPDATE

Issued 930 PM CST CST Mon Dec 22 2025

Dry air beneath the low stratus clouds overspreading southern WI this evening has reduced drizzle accumulations to near zero up to this point. Some ~30% drizzle chances remain in the forecast over the next few hours for portions of eastern WI, but Satellite clearly shows a rapid clear out in the low-level clouds approaching from the west, which will cut off the drizzle chances. Air temperatures are progged to remain above freezing with any lingering drizzle this evening, with the potential to drop near or just below freezing arriving long after the clouds and slight drizzle chances are gone. Hence, freezing drizzle concerns in the near term are much lower than prior expectations.

Scattered to broken cirrus and cirrostratus clouds (at high altitudes) will continue to pass through the region later overnight, helping to reduce radiational cooling. A weak dry cold front passes the region late overnight into Tuesday morning, with a light northwesterly breeze developing later Tuesday morning behind it. Some high altitude clouds linger, but with ample sunshine for daytime highs to reach the upper 30s to mid 40s across the region Tuesday.

Sheppard

SHORT TERM

Issued 332 PM CST Mon Dec 22 2025

Tonight and Tuesday:

Steady warm air advection will continue into this evening, before a weak cold front moves east through the area later tonight. Most model forecast soundings continue to show a fairly moist to saturated low level layer developing by early this evening, with the middle to upper levels drying out and removing ice crystals. Thus, drizzle is expected to move through the area into this evening before ending later tonight with the frontal passage.

There may be some light freezing drizzle as well over northern portions of the area during this period, if temperatures can drop to the freezing mark. There is some uncertainty if temperatures will actually drop much tonight in this area before the frontal passage, as the steady warm air advection may keep temperatures relatively steady.

Temperatures will be close, so have kept in some light freezing drizzle in the forecast for the northern parts of the area north of Madison and Milwaukee. Will message this light freezing drizzle potential with slick spots in the Weather Story graphic. There may be some refreeze potential in this area as well for the Tuesday morning commute, as temperatures remain near freezing.

West northwest winds will then linger through Tuesday, with perhaps some scattering out of the clouds by later in the day. Highs will remain mild, from the upper 30s north to the lower to middle 40s southeast.

Wood

LONG TERM

Issued 332 PM CST Mon Dec 22 2025

Tuesday night through Monday:

The extended models have fairly good agreement for much of the week but then diverge for the weekend as cyclogenesis may occur over the Great Lakes and Ontario.

For Tue nt, a sfc ridge over nrn MN and adjacent Canada will build sewd to the nrn Great Lakes and MI by 12Z Wed. Thus the sfc ridge will shift across srn WI with temps dropping into the 20s for lows. Ssely sfc winds and warm advection will begin on Wed as the high moves away and a wave of low pressure tracks from the central Great Plains into the Ohio Valley through Wed nt. In addition, another sfc trough will track across the nrn Great Lakes and nrn WI during this time. Aloft a vorticity maximum is expected to traverse across srn WI during this time in conjunction with low to mid level warm, moist advection. Either drizzle or very light rain may develop (30-50%) for Wed evening over se WI with slight chances (20%) elsewhere. A weak cold front will then follow.

Large polar high pressure will then follow across Ontario with shortwave ridging aloft over srn WI on Thu. Nly winds will shift ely but relatively mild temps will continue. For Thu nt, a shortwave trough will track from the nrn Great Plains toward the nrn Great Lakes, while at the sfc a wave of low pressure will track from the central Great Plains across the nrn Ohio Valley through Fri. The warm, moist advection will bring 50-70% chances for rain late Thu nt, possibly lingering into Fri AM.

A more significant upper trough will then move ewd across srn Canada inducing some degree of cyclogenesis over Ontario or the Great Lakes for the weekend. There is wide spread with the details, but strong cold advection and a polar airmass will likely follow for Sat nt-Mon. Relatively mild temps continue through Sat then much colder.

Gehring

AVIATION

Issued 930 PM CST Mon Dec 22 2025

Some lingering ~30% drizzle chances in eastern WI over the next few hours due to a lingering deck of low stratus (MVFR to Fuel Alt MVFR ceilings present as of 9 PM CST). Satellite indicates a rapid clear-out of the low-level clouds is approaching from the west, and should restore most areas to VFR ceilings late tonight (some SCT to BKN high-altitude cirrus / cirrostratus clouds should remain in place). Light south winds veer west late overnight, then northwest around 10 kt by late Tuesday morning as a weak dry cold front passes through the region.

Dry weather and VFR with a light northwest breeze expected for Tuesday. Some SCT to BKN high altitude clouds linger.

Sheppard

MARINE

Issued 332 PM CST Mon Dec 22 2025

A Small Craft Advisory remains in effect into this evening from Port Washington northward, mainly for elevated waves of 4 to 6 feet.

South winds this evening will shift southwest later tonight and west on Tuesday, as low pressure around 29.8 inches moves into Ontario. Winds will shift west northwest by Tuesday afternoon, as high pressure around 30.4 inches moves from North Dakota into northern Minnesota. Winds will subside Tuesday night, as the high crosses Lake Michigan. These winds will shift out of the southeast Wednesday, as the high moves east of the region.

Another stronger high around 30.5 inches will move east across southern Manitoba into Ontario Wednesday night into Christmas Day, with winds steadily increasing out of the northeast to east.

Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.