textproduct: Milwaukee/Sullivan

KEY MESSAGES

- A Slight Risk (2 out of 5) for severe weather exists this afternoon. Primary risks will be hail and gusty winds, though the strength of the storms is not expected to be comparable to yesterday. Southwest Wisconsin and areas along the WI/IL border have the best chances to see a strong to severe storm.

- Heavy rainfall from more thunderstorms this afternoon and evening could lead to additional periods of flooding into Thursday morning. A Flood Watch has been issued for all of southern Wisconsin.

- Additional windows for heavy rainfall, flooding, and severe thunderstorms Friday into Saturday.

SHORT TERM

Issued 335 PM CDT Wed Apr 15 2026

Tonight through Thursday night:

More thunderstorms are possible this evening as return flow is expected to advect appreciable SBCAPE from 1000 to 1500 J/kg into southwest WI and up to the WI/IL border. Storms tonight may be a bit weaker than yesterday given skinnier CAPE profiles, but low level instability, effective shear around 40 knots, and some curvature in the hodographs will support another round of gusty winds and hail. An isolated tornado can't be ruled out along the WI/IL border given the low level turning in the hodographs and low level instability, provided a low-topped supercell forms in the environment this afternoon.

Storms will quickly grow upscale after sunset, leading to more widespread rain. Training thunderstorms may lead to more flash flooding tonight given the wealth of rain we've had this week. A Flood Watch is in effect from 4pm this afternoon to 7am Thursday for the expected rainfall tonight. A widespread 1 to 2 inches may fall, with locally higher amounts possible where any thunderstorms track.

Storms largely move offshore tonight around midnight, with more scattered rain possible between midnight and 7am. Rain should then largely taper off Thursday morning, with dry conditions Thursday afternoon. A weak surface ridge will then move overhead Thursday night.

CMiller

LONG TERM

Issued 335 PM CDT Wed Apr 15 2026

Friday through Wednesday:

A strong cold front is expected to move through Friday afternoon and evening and is expected to lead to another round of severe weather. At this time the GFS depicts strong warm ahead of the front which will allow dew points in the 60s to return northward. Model soundings depict 40 knots of effective shear amid moderate instability of 2000 J/kg, with low level turning in the hodographs. This would support all modes of severe weather again for the area. At this time the SPC has included southwest and south central Wisconsin in an enhanced risk for severe weather.

The cold front will then come crashing through Friday night into Saturday, and temperatures will dip into upper 40s to low 50s for the weekend. Saturday is expected to be cool and breezy, with breaks in the clouds late in the day. Sunday will feature similar conditions but will be a tad bit sunnier as a high pressure center moves overhead.

Warmth is then expected to return next week Tuesday as a ridge builds over the central United States. The middle of next week then looks active again as a low pressure moves off of the lee of the Rockies.

CMiller

AVIATION

Issued 307 PM CDT Wed Apr 15 2026

MVFR and VFR conditions generally exist over most of the area while IFR is hanging on over east central WI. Thunderstorms are expected to move in late this afternoon and evening into the west and grow upscale, leading to widespread rain over the area. Before storms grow upscale, hail and gusty winds will be possible with any strong storms over southwest Wisconsin and the WI/IL border. Winds will generally be light and variable overnight as a front sinks south over the region, becoming northerly by daybreak on Thursday. More fog is possible tonight mainly over southeast, east central and central WI, with some dense fog possible.

CMiller

MARINE

Issued 251 PM CDT Wed Apr 15 2026

A stationary front will remain parked over the middle third of the lake this afternoon, slowly sinking south to the southern end of the lake by noon Thursday. A Marine Dense Fog Advisory continues until Thursday morning while this front lingers. Winds will remain southerly south of the front and modestly breezy, while winds north of the front will remain light and variable to northerly during this time. The front will then clear the lake Thursday afternoon and northerly winds will prevail over whole lake. Winds will become light and variable briefly Thursday night as a weak ridge passes over the lake, with winds then becoming southerly and breezy Friday ahead of low pressure of 29.6 inches approaching from the west. Gusty northwest winds then return following a cold front Friday night.

Additional thunderstorms are forecast over the southern third of Lake Michigan this evening into tonight. A few storms could be severe with large hail being the primary concern. Additional storms are possible Friday into Saturday, with a few stronger storms possible.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

WI...Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058- WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067- WIZ068-WIZ069-WIZ070-WIZ071-WIZ072 until 7 AM Thursday.

LM...Dense Fog Advisory...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563- LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671- LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874- LMZ876-LMZ878 until 7 AM Thursday.