Area Forecast Discussion

KEY MESSAGES

- Widespread showers and scattered thunderstorms expected through the night into Tuesday morning. Locally heavy rain and urban and small stream flooding are possible, especially for low-lying and urban areas west of a line from Port Washington to Janesville.

- Gale warning and small craft conditions expected for southern WI waters through tonight. - A High Swim Risk is expected from the Sheboygan County beaches south to Kenosha County Beaches tonight into Tuesday morning due strong onshore winds and building waves of 4-9 ft.

- Midweek shower and storm chances, but better chances for areas along and south of the WI/IL border. Additional shower and storm chances into the weekend.

SHORT TERM

Issued 1152 PM CDT Mon Sep 14 2026

Tonight through Wednesday:

A sw-ne oriented band of showers and scattered storms from ne IA to central WI is expected to lean over to the east to southeast through the night. This will coincide with the axis of the swly 50-60 kt low level jet and the arrival of high sfc-925 mb moisture content. Elevated CAPE up to 1500 J/KG is expected but with a deep frontal inversion in the early morning hours. The sswly low level jet will veer into se WI and nrn IL toward 12Z Tue with a weakening trend. It still appears the veering of the low level jet will maintain a progressive leading edge of deep convection, although additional showers and storms will develop in its wake and last toward mid to late Tue AM. Overall though, believe the heavy rainfall rates will be limited with localized exceptions. Antecedent conditions have also been dry. Will continue to message the potential for urban and small stream flooding, greatest well west of the MKE metro area.

The weakening and slowing trailing cold front will then pass Tue afternoon but the lift will be weak and some capping will be in place by then. The front is then expected to push into central or srn IL for Tue nt-Wed as high pressure shifts ewd across the nrn Great Lakes. Mostly dry conditions are expected during this time.

Gehring

LONG TERM

Issued 1152 PM CDT Mon Sep 14 2026

Wednesday night through Monday:

A weak wave of low pressure and shortwave trough aloft is expected to track along the stationary front over nrn or central IL for Wed nt-Thu. Meanwhile a large high pressure area will move into wrn Ontario late on Thu, then across Ontario into Quebec for Thu nt-Fri. The high will likely suppress the showers and storms farther to the south than prior forecasts. Rain chances range from 30-50 percent with highest probabilities near the IL border late Wed nt.

For Fri-Sun, cyclogenesis may accompany a shortwave trough moving ewd across the Great Plains into the Great Lakes and bring more showers and storms to the region. There is uncertainty with the track and overall evolution of the trough. Nevertheless, 60-80 percent chances of rain are forecast for late Fri nt-Sat. with lessening chances into Sun-Mon. Temps will be near normal for this period.

Gehring

AVIATION

Issued 1152 PM CDT Mon Sep 14 2026

Widespread showers and scattered thunderstorms will move east to southeast across srn WI from late this evening through Tue AM. MVFR to IFR Cigs will then gradually develop from sw WI sewd to south central WI during the early morning hours of Tue, then expand into se WI after 12Z. Much of the showers and storms will exit far srn WI by Tue afternoon followed by a decrease in MVFR Cigs from central WI toward nrn IL through the afternoon. VFR conditions are then expected Tue nt.

Gehring

MARINE

Issued 1152 PM CDT Mon Sep 14 2026

Southerly winds will increase to gales by midnight and continue through the night. A Gale Warning is in effect. The gales will then decrease from south to north across the lake through Tuesday morning. The southerly gales are a result of low pressure around 29.3 inches tracking from southern Manitoba toward southern Hudson Bay through Tuesday. The trailing cold front will then slow and weaken as it moves across the lake Tuesday afternoon into early evening. Modest northwest winds Tuesday evening will shift to northeasterly by early Wednesday morning as high pressure around 30.4 inches moves across the northern Great Lakes. Lighter winds will then prevail Wednesday night into Friday until stronger southerly winds return Friday night and Saturday ahead of another low pressure area approaching from the Great Plains.

Gehring

MKX WATCHES / WARNINGS / ADVISORIES

WI...Beach Hazards Statement...WIZ052-WIZ060 until 1 PM Tuesday.

Beach Hazards Statement...WIZ066-WIZ071-WIZ072 until 7 AM Tuesday.

LM...Gale Warning...LMZ080-LMZ366-LMZ565-LMZ567-LMZ643-LMZ644- LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870- LMZ872-LMZ874-LMZ876-LMZ878 until 7 AM Tuesday.

Gale Warning...LMZ261-LMZ362-LMZ364-LMZ563 until 1 PM Tuesday.

Small Craft Advisory...LMZ645-LMZ646 until 7 AM Tuesday.