textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Rain is likely (about 60 to 90 percent chances) area wide late tonight across all of southern Wisconsin.

- Temperatures continue to trend well above normal into Sunday followed by windy conditions and polar air for Sun nt-Mon. Temperatures remaining at or below normal into the middle of next week. - Northwest gales are looking likely for all of Lake MI Sunday night into Monday evening.

SHORT TERM

Issued 225 PM CST Thu Dec 25 2025

Tonight through Monday night:

For tnt, sfc-850 mb warm, moist advection will increase as a wave of low pressure will track from the central Great Plains to north central IL by 12Z Fri. Aloft a shortwave trough will approach from the west and reach central WI by 12Z as well. Fcst soundings are having difficulty saturating into the mid levels, but enough moisture and saturation is present for initially drizzle late this evening then light rain late tnt into Fri AM. The temperature forecast warms the air temps just above freezing north of Madison but any isolated pockets of cooler air could result in a brief period of icing with melting to follow. The shortwave trough and lingering light rain will exit during Fri AM with the sfc low to move across the nrn Ohio Valley through the day. With the absence of any meaningful cold advection followed by the passage of only weak high pressure Fri nt, widespread stratus will continue.

Sly winds and warm advection will ensue for Sat as weak high pressure moves away and low pressure tracks from the nrn high plains to KS. This is in response to a couple shortwave troughs. One will track along the US/Canadian border with a stronger shortwave trough to its south moving into the central Great Plains. The extended models have much better agreement on the srn shortwave trough and eventual cyclogenesis as dominant over the nrn upper wave, although they come very close to merging.

The sfc low will be over ern KS at 12Z Sun with an inverted trough extending through WI. Very light rain or drizzle may develop (20-40% chance) late Sat nt via the low level warm, moist advection. Cyclogenesis will then ensue on Sun with a 1001 mb low reaching wrn Lake Erie by Sun evening then deepening into the 980s mb by 00Z Tue over far srn Quebec. Rain chances have increased to 50-60% Sun afternoon and/or evening as the main tropospheric temperature gradient and potential frontogenesis shifts through the area ahead of the approaching shortwave trough from the west. Brisk nwly winds and cold advection will ensue during this time with rain changing over to a little light snow Sun nt then possibly lingering into Mon AM. Lows will drop into the teens by sunrise Mon with high temps in the upper teens to middle 20s. Single digit below zero wind chills are forecast during this time. Decreasing nwly winds are likely Mon nt with lows from 6 to 11 above.

Gehring

LONG TERM

Issued 225 PM CST Thu Dec 25 2025

Tuesday through Thursday:

Colder conditions continue through the end of the extended period as northwest flow takes hold behind Monday's trough. A couple modest clipper systems look possible Tuesday and then Wednesday night into Thursday, though ECMWF and GFS solutions vary on the track. Given highs in the teens to 20s, both systems will likely bring light snow, rather than mix or rain. At this time the NBM generally favors 15% PoPs mainly north of I-94 for both systems.

CMiller

AVIATION

Issued 225 PM CST Thu Dec 25 2025

Areas of MVFR Cigs will continue this afternoon and early evening. Widespread Cigs then falling well below 1 kft late this evening through Friday as drizzle and light rain moves into srn WI. The widespread light rain and BR will drop vsbys to 1-3SM through Fri AM, although patchy fog of 1/4-1/2SM will be possible over south central WI during this time. Vsbys improve for Fri afternoon but Cigs will mostly remain below 1 kft.

Gehring

MARINE

Issued 225 PM CST Thu Dec 25 2025

Modest northeast winds today shifting easterly toward evening as high pressure of 30.5 inches moves east across northern Ontario. The high will then move across Quebec tonight into Friday morning, while low pressure of 29.7 inches moves across northern Illinois and the northern Ohio Valley. This will generate breezy southeast winds across the entire lake but remaining below gale force. Much lighter and variable winds will then take hold later on Friday into Friday night.

Modest southeast winds will then return for Saturday through Sunday morning as low pressure organizes over the central Great Plains and moves to northeast Illinois by noon Sunday as a 29.7 inch low pressure area. The low will then deepen to 29.2 inches by Monday morning over southern Ontario, reaching southern Quebec at 29.0 inches later in the day. Thus northwest gales are looking likely Sunday night through Monday evening over Lake Michigan. Much colder air will also pose a risk for freezing spray during the period of gales.

A Small Craft Advisory is in effect from Sheboygan to Winthrop Harbor for high waves, and brisk northeast winds today shifting southeast this evening and remaining gusty.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 2 PM Friday.