textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Mostly dry tonight into tomorrow, save for a few potential showers along the lake breeze this afternoon.

- Dense fog Advisory in effect mainly for counties close to Lake Michigan but extension further west may be needed. Marine Dense Fog continues into Friday morning.

- A Flood Watch is out for all of southern Wisconsin from 1pm Friday to 7am Saturday for more heavy rain Friday afternoon and evening.

- Another round of heavy rainfall, flooding, and severe thunderstorms is expected Friday afternoon into Friday night. An Enhanced Risk (3 out of 5) for severe weather exists over the western half of the CWA.

UPDATE

Issued 650 PM CDT Thu Apr 16 2026

Dense Fog Advisory has been issued for areas closer to the lake as dense fog has begun to develop over the lake and roll in causing the expectation that with model guidance we should dense fog overspread at least eastern portions of the CWA but expansion may be needed further west. Low clouds and fog concerns may extend as far west as Madison tonight and likely clear by mid morning. This will be the main concern for the tonight period as conditions otherwise remain quiet and dry.

Kuroski

SHORT TERM

Issued 208 PM CDT Thu Apr 16 2026

Tonight through Friday night:

Subsidence will linger over the region tonight as a weak surface ridge moves southeast over southern Wisconsin. As winds ease, fog is expected to occur for the counties adjacent to Lake Michigan, given the ample surface moisture that is present over the region. This fog may become dense and a dense fog advisory may be needed.

Tomorrow, a warm front is expected to lift north across the region as a rapidly moving surface low lifts northeast from Omaha near daybreak to Duluth by the late afternoon and drags a cold front through the area. Given the fast motion of the low, warm advection will occur quickly, and northerly moisture return is expected to push the warm front into Northern Wisconsin. Following the warm frontal passage, daytime heating is expected to allow for moderate to high instability to build over the state, with CAMs showing model soundings supportive of 3500 J/kg of SBCAPE along the MS River Valley by 1PM in the afternoon. As the surface low passes the area as it races northeast, lift from the surface low will drive forcing for ascent and storm development is expected to rapidly occur near the MS River Valley, with storms then traveling east into southern Wisconsin. Models suggest convective initiation may occur between 2-4 PM, with activity then moving through southern WI through the rest of the afternoon into the evening.

CAM soundings and model guidance suggests that the initial mode should be supercells in southwest to south central WI, before storms conglomerate into lines as they travel east over southern Wisconsin and transition to a QLCS mode. Given lapse rates of 8 C/km, turning in the low level hodograph, and 3CAPE eclipsing 200 J/kg, initial supercells will be capable of all severe weather hazards. As storms go linear with eastward extent through southern, instability may lessen, but will still be enough to support gusty winds, and a brief spin-up QLCS tornado to the lakeshore.

On top of the thunderstorm threat, flooding is again a concern given the anticipated rainfall with the storms and saturated antecedent conditions. A widespread 1 to 2 inches of rain is expected, with locally higher amounts possible. A Flood Watch is anticipated from 1pm Friday to 7am Saturday.

CMiller

LONG TERM

Issued 207 PM CDT Thu Apr 16 2026

Saturday through Thursday:

Cold advection takes hold Saturday following the passage of the cold front. Rain is expected to end fairly quickly following the front and skies should clear out during the late morning. Given the CAA and breezy northwesterlies, high temperatures will only reach from the mid to upper 40s to low 50s across the area. High pressure will begin to slowly build in on Sunday, but breezy northwesterly winds will continue out ahead of the high. Similar high temperatures to Saturday are expected on Sunday.

Monday, the high pressure center moves overhead and shifts east. Light southerly winds return and slightly warmer temperatures in the 50s are expect. Ridging then builds over the plains, and warmth builds Tuesday with highs in the 70s. We'll then remain on the edge of the ridge into the middle of next week with warm temperatures lingering. Very nebulous probs for storms (15 to 25%) return on Thursday.

CMiller

AVIATION

Issued 650 PM CDT Thu Apr 16 2026

VLIFR/LIFR CIGS and VSBYS are currently developing over Lake Michigan and will roll in off the lake tonight with MKE already having dropped to dense fog. With that we have issued a Dense Fog Advisory through 14z Friday for expected expansion of dense fog across areas near the lake tonight. In fact model guidance suggests there may be need to expand further west toward south central WI but will hold off on that for now. As we break into daylight Friday morning expect fairly rapid dissipation of the fog and low CIGS by mid morning.

Then attention turns toward the severe storm potential during the day and evening Friday. Still plenty of uncertainty on the timing of storm initiation and who will get hit when but storms appear likely to impact all of southern WI at some point with storms into western WI as early as noon. However, more widespread chances are to be expected by the later afternoon and early evening with storms tracking across southern WI into the evening. Storms are generally expected to weaken as they push east especially with the afternoon lake breeze potentially being fairly strong and impacting convection further east. Storms are generally expected to push out of southern WI by the late evening hours. Some VSBY and CIGS concerns will come with the storms as well though they would be associated directly with storms.

Kuroski

MARINE

Issued 121 PM CDT Thu Apr 16 2026

A weakening boundary is slowly moving toward the southern end of Lake Michigan. This boundary is expected to clear the southern end of Lake Michigan this evening, with winds becoming light and variable tonight for a time as a weak surface ridge moves over the lake. Dense fog will continue over the lake through this time. Winds then come around to southerly tomorrow morning as a surface low of 29.5 inches approaches from the central plains. This surface low will quickly move from Omaha to Duluth from the morning into the afternoon. Winds will become gusty and southeasterly Friday night, and strong to severe storms will move east over the lake as a cold front sweeps through the area. Winds then become northwesterly behind the cold front Saturday morning. Breezy northwesterly winds then continue Saturday through Sunday as the low then races northeast toward Hudson Bay.

Winds ease Monday morning as high pressure move southeast over the upper Great Lakes.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

WI...Dense Fog Advisory...WIZ052-WIZ059-WIZ060-WIZ065-WIZ066-WIZ071- WIZ072 until 9 AM Friday.

Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058- WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067- WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...1 PM Friday to 7 AM Saturday.

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 Friday.