Area Forecast Discussion

KEY MESSAGES

- Additional storm development is expected this afternoon and evening, particularly along and south of Interstate 94. Additional heavy downpours and flooding impacts would be the main concerns.

- Prolonged period of high swimming risk conditions continues into Tuesday at all Lake Michigan beaches, and may need to be extended into Wednesday evening.

SHORT TERM

Issued 227 PM CDT Sat Sep 19 2026

This Afternoon through Sunday night:

Afternoon showers looking likely for srn WI as a MCV and modest WAA and Fgen in the low to mid levels continues. There will also be increased storm potential primarily into the late afternoon and evening as instability tries to work back into the area. Models generally suggest that there will at least be potential for storms along and south of I-94 where we should remain south of the front for a time. This was thought to potentially have some severe risk but given the lowered trends in MUCAPE (300-600J/kg) and the likelihood that we will be cloudy was suggestive that any storms may largely be elevated with little to no MLCAPE.

Cold pooling from those storms and/or just the general model trends of the front shifting south suggest this will shift south of the CWA in large part by the mid to late evening. As this shifts out, so will our storm risk and in large part our precip chances as well. Its worth noting that a slight shift north or slower frontal progression with bring a longer period of precip and storm potential into the evening and overnight but models are largely consistent, keeping precip/storms later tonight mostly south of the WI/IL border. The vast majority of CAMs suggest most of potential activity this evening being located south of the border but a few models still have this activity in far southern WI before exiting to the south and thus some of the risks still remain. We have elected to extend the Flood Watch for the southern 2 tiers of the CWA until 12z Sunday.

Into Sunday, things have been trending quieter. Other than some lingering showers pushing out in the morning the surface low looks to push ESE with the high in central Canada nudging a bit more into the region shoving precip potential south. In fact, we may also lose midlevel moisture in large part across the area which further lends to the idea of a mostly dry Sunday and perhaps even a peek at some sunshine toward central WI.

Otherwise, Beach Hazards Statement remains in effect for onshore winds bringing waves to 6-10 feet in the nearshore areas Sunday. While, winds are lighter right now with waves around 4 feet in the nearshore but at winds increase from the northeast Sunday waves will rapidly increase making for very dangerous nearshore conditions.

Kuroski

LONG TERM

Issued 227 PM CDT Sat Sep 19 2026

Monday through Saturday:

A large 1035 MB high pressure area will track from Ontario into Quebec through Wed bringing persistent east northeast winds to srn WI. Upper ridging will track with the sfc high, while a slow moving upper trough tracks from the nrn and central Great Plains across WI and IL from Mon nt-Wed. The track of the individual vorticity maximums within the trough will determine the locations of the showers, and whether dry low level air can be overcome. At this time rain chances are ranging from dry over east central WI to 40-50 percent chances over sw WI and far srn WI. Mostly cloudy skies will keep temps below normal.

For later in the week, weak nwly flow aloft is expected but with better chances for sunshine and high temps returning to near 70F.

Gehring

AVIATION

Issued 227 PM CDT Sat Sep 19 2026

Scattered to numerous showers and isolated storms will continue this afternoon and tonight. The major TAF concern will be the LIFR to IFR CIGS expected through tonight before they begin pushing out Sunday morning. In addition with rain, comes VSBYS degradation, and some fog though the winds should be breezy enough to limit that potential. VFR conditions expected to return from north to south Sunday morning.

Kuroski

MARINE

Issued 227 PM CDT Sat Sep 19 2026

Low pressure around 29.8 inches will move just south of the southern portions of the lake tonight. Winds will shift northeast tonight as the low passes to the south. Areas of widespread showers and thunderstorms will accompany the passing area of low pressure later this afternoon through tonight, though mostly on the southern third of the lake.

Gusty east to northeast winds are then expected Sunday through Monday night, as low pressure slowly moves into the Ohio River Valley. High pressure around 30.5 inches will move southeast into Ontario during this period. Gusts could occasionally approach gale force Sunday into Monday night, mainly over western half of the southern portions of the lake. Winds will steadily taper Tuesday through Wednesday, as the high pressure system moves into Quebec and New England.

Kuroski

MKX WATCHES / WARNINGS / ADVISORIES

WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072 until 7 PM Tuesday.

Flood Watch...WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068- WIZ069-WIZ070-WIZ071-WIZ072 until 7 AM Sunday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM Tuesday.