textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Wind chills in the -5 to -15 degree range expected this evening into tonight.

- Light wintry precipitation Friday evening.

- Several potential chances for snow through mid week next week.

SHORT TERM

Issued 315 PM CST Thu Dec 4 2025

Tonight through Friday night:

The core of the surface high pressure system is passing overhead at the moment, hence the perfectly clear skies and nearly calm wind. As the high weakens and drifts east, southwesterly winds will begin to develop this evening, and with the snow covered grounds and mostly clear skies priming the environment for radiational cooling, wind chills of -5 to -15 are expected to occur this evening through just after midnight tonight. The corresponding air temperatures bottom out in the single digits to around zero. Late tonight, the brute force warm air advection and increasing cloud cover will allow the temperatures to increase a few degrees before sunrise Friday morning. WAA continues into the daytime hours of Friday, with high temps lifting into the 20s.

A clipper system yields a brief period of 20-50% precip chances late Friday afternoon through Friday evening. The associated cold front crosses the region around midnight Friday night, with winds veering northwest and conditions drying out behind it. If applicable at all, this precip would amount to either a dusting of snow or a thin glaze / trace of freezing drizzle (or a wintry mix of both). The uncertainty with the precipitation type is due to the very shallow nature of the moisture in forecast soundings, which may or may not reach the DGZ to form cloud ice.

Sheppard

LONG TERM

Issued 315 PM CST Thu Dec 4 2025

Saturday through Thursday:

To sum up the entire long-term forecast, temperatures remain cool, and occasional clipper systems (fast moving low pressure systems) yield short periods of snow chances.

The passage of a weak surface ridge on Saturday will lead to relatively slow northwest winds and dry weather, with highs remaining in the 20s. The first clipper system arrives Saturday night, delivering snowfall in the ballpark of a dusting to 2 inches. Light snow chances taper off into Sunday morning as the clipper exits. We're expecting a light north breeze and highs in the upper teens to 20s for Sunday afternoon.

Similar clipper systems, some with slightly stronger dynamics, are then expected off and on into the early half of next week. High temperatures remain below freezing, likely making their closest approach to the freezing mark (warmest) on Tuesday or Wednesday before trending back down.

Sheppard

AVIATION

Issued 315 PM CST Thu Dec 4 2025

Clear skies through the rest of the afternoon, with high and mid altitude clouds building to broken coverage overnight tonight. We may see some ceilings as low as 4,500 ft tonight, still VFR though. Southwesterly low level wind shear is expected late tonight through early Friday morning, and is included in TAFs as a 2,000 ft wind at around 40 kt. The core of the low level jet (LLJ) is centered over central WI tonight, so far southeastern WI airports (KMKE, KENW) did not receive LLWS in the 18z TAF issuance, future issuances may add it if positioning of the LLJ changes or speeds increase.

LLWS dissipates into Friday morning, with a light southwesterly breeze continuing at the surface. Dry weather is expected through mid Friday afternoon, from then through Friday evening there will be chances for light snow or patchy freezing drizzle. These would only accumulate to a dusting (snow) or a thin glaze (ice) if applicable.

Sheppard

MARINE

Issued 315 PM CST Thu Dec 4 2025

Southwest winds will increase this evening to gale force over the northern half of the lake as an area of low pressure around 29.6 inches moves across southwestern Ontario. A Gale Warning is in effect from late this evening through mid morning Friday. Freezing spray is also expected during this time.

A cold front extending south of the low will cross the lake Friday night. Southwesterly winds remain breezy (25-30 kt gusts) ahead of the cold front Friday, gradually subsiding and veering northwest behind it. Northwest winds gradually decline throughout Saturday then become light and variable Saturday evening as a weak surface ridge of high pressure builds into the region. Stronger high pressure tracking southeastward through the Dakotas and a weak low pressure system tracking eastward past southern Illinois will work together to drive north winds around 20-25 kt on Sunday.

Sheppard

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ868...9 PM Thursday to 9 AM Friday.

Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...10 PM Thursday to midnight Saturday.