textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Patchy frost overnight

- Chance for rain Thursday night trending lower

- Warm and humid conditions with increasing storm chances late this week into early next week

SHORT TERM

Issued 1121 PM CDT Wed May 13 2026

Overnight through Friday:

Skies cleared and the northerly winds diminished quickly this evening with the sunset. High pressure, clear skies, calm wind, and dewpoints in the mid 30s will allow temps to cool into the upper 30s tonight. There will be a few pockets of cooler temps, closer to 36. Thus, patchy frost is possible late tonight, especially within the Rock River valley and toward central WI.

High pressure will slowly cross Wisconsin and lower Michigan tonight through Thursday night. This means light winds for southern WI with a lake breeze developing by early afternoon, pushing inland in the late afternoon and early evening. The return flow around the high will give us high temps in the lower 70s west of Madison.

An upper trough associated with a closed upper low tracking across the Canadian Plains will cross MN and WI Thu nt into Fri morning. The strongest mid level forcing will be closest to this upper low, so over northern WI, but weak 850mb warm air advection will be ongoing over southern WI. In addition, a weak shortwave will be crossing IA and northern IL. So the forecast 6-hrly precip fields in the models shows up as a north-south band of rain crossing WI Thu nt into Fri morning. However, the precip should be light, scattered, and probably with the steadier precip focused toward northern WI and northern IL (splitting around southern WI). This event is not a promise for a soaking rain for us.

Once the trough clears us by mid morning, expect sunshine and high temps in the upper 70s to around 80 on increasing southerly winds.

Cronce

LONG TERM

Issued 1121 PM CDT Wed May 13 2026

Friday night through Wednesday:

Thunderstorms are looking more likely to develop in the Plains (Kansas/northern MO/southeast IA) Friday evening on the nose of the low level jet. If a large complex develops, it would track into northern IL and may be clip southern WI late Fri nt. There is uncertainty in how far north this complex could get, so southwest WI and portions of south central WI were included in the afternoon Day 3 SPC Convective outlook. Models seem to favor the southern route at this time (not in WI).

The Midwest weather pattern will become more active Saturday through Monday as an upper trough develops in the western US. Southern WI has chances for thunderstorms each afternoon/evening/overnight, but our chances will be closely tied to where the previous complex diminished, and where the effective warm front sets up. The day with the strongest forcing closest to southern WI will be Monday.

Saturday highs will be in the lower 80s. With westerly winds of 10 mph or less, the lake breeze may be able to overcome it by late afternoon, but that will be late enough for lakeshore highs in the upper 70s. Sunday will be a reload day in terms of heat and humidity, and we may see some showers and thunderstorms with warm air advection, mainly in south central WI. Highs Sunday should have a large gradient across southern WI, ranging from the lower 60s near Sheboygan to the lower 80s near Darlington (Lafayette county).

Monday looks very warm (highs in upper 80s), but only if the warm front can get all the way up into northern WI and if the precip holds off until the afternoon.

Cronce

AVIATION

Issued 1121 PM CDT Wed May 13 2026

Light and variable winds are expected during the day Thursday, with a lake breeze developing early in the afternoon and pushing inland to Waukesha by late afternoon. Elsewhere, winds will become southerly.

Scattered light rain showers are possible Thursday night, but low levels should be quite dry, so VFR conditions will continue. Friday morning, gusty southwest winds and brief MVFR ceilings are possible.

Cronce

MARINE

Issued 1121 PM CDT Wed May 13 2026

Light northerly winds Thursday morning will become southerly by Thursday night as high pressure around 30.1 inches crosses the Upper Great Lakes. Breezy southerly winds are expected Friday, with a few gales possible Friday afternoon and evening in northern portions of the lake. South to southwest winds then linger Friday night into Saturday. Easterly winds should then increase gradually Sunday as a warm front lifts across Wisconsin and Lake Superior, ahead of low pressure around 29.5 inches tracking toward the Minnesota Arrowhead.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

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