textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Additional severe storms possible Wednesday afternoon if a front remains stalled across the area. If the front sets up south of the area, severe potential will greatly decrease but flash flooding will remain possible due to training convection.

- Heavy rainfall could lead to additional periods of flooding this afternoon into Wednesday. Additional Flood Watches are possible especially tomorrow.

- Additional windows for heavy rainfall, flooding, and severe thunderstorms Friday into Saturday. All severe hazards will be possible later Tuesday afternoon into the evening.

SHORT TERM

Issued 1001 PM CDT Tue Apr 14 2026

Overnight through Wednesday:

The elevated environment will remain unstable as we remain in the warm sector with upper divergence, weak vorticity advection, and mid level warm air advection overhead. This will allow for a few storms to percolate across portions of central and southern WI overnight. Given the lingering high MUCAPE, a few storms could approach marginal severe levels at times and bear watching. The threat will wane as the night goes on and as the LLJ veers.

The effective surface boundary should be stationed over northern IL Wednesday morning as a weak mid level shortwave trough tracks across the region. Southern WI may see scattered showers and a few thunderstorms with the overriding of the boundary in the morning and midday Wed.

A deeper shortwave trough will track across NE Wed morning and into western IA by early evening. The associated surface low on the leading edge should help lift that boundary into southern WI during the late afternoon and evening hours. Storms within the warm sector will have the potential for severe-level hail and wind. Heavy rain is a threat with this system. We may need an areal flood watch.

Meanwhile, there will be a steady northeast wind off Lake Michigan and keep the air stable with low clouds and patchy fog, especially north of Milwaukee. How far inland the fog/stratus get Wed morning is still uncertain. Wherever the boundary between the lake air and the warm, unstable air lands Wed afternoon, this will be an extra focus for low level helicity and the potential for a brief tornado along this boundary if storms become strong enough.

Cronce

LONG TERM

Issued 1001 PM CDT Tue Apr 14 2026

Thursday through Tuesday:

That deeper shortwave trough that went across IA Wed night will track across southern WI Thursday morning. Scattered showers and a few thunderstorms are expected with this feature, especially in the morning with deeper moisture still in place over the region. The chance for showers and thunderstorms will linger into the afternoon. As the deeper moisture departs during this time and we heat up, the low level lapse rates will increase to allow for instability (up to 1000 j/kg) to develop. A lake breeze should push inland and help to trigger some of the showers/storms. Look for the precip chances to exit by sunset.

High pressure will pass through Thursday night and lows will dip into the 40s wherever the lake breeze hit, so bisecting southern WI from east to west. Friday morning and early afternoon look quiet, but we will be getting primed for the next system to arrive Friday late afternoon and night.

Low pressure tracking across the northern Plains on Friday, in response to a high-amplitude upper trough, will cross Lake Superior Friday night. A strong cold front will slide across WI from west to east late Friday night through Saturday morning. Showers are thunderstorms are expected within the warm sector Friday afternoon/evening and also along the cold front. Scattered showers are possible behind the front during the day Saturday. Strong cold air advection will follow, so low temps should dip down to around or below freezing Saturday night on brisk westerly winds. The models dry out the atmosphere quickly, but if there happens to be any lingering moisture, the precip type would chance to flurries/snow.

Brisk westerly winds will persist through Sunday. Finally, high pressure will dominate and give us dry weather through Monday or Tuesday. The weather pattern has a large degree of uncertainty beyond Monday between the models.

Cronce

AVIATION

Issued 1001 PM CDT Tue Apr 14 2026

The main area of storms exited southeastern WI but there are a few lingering showers and thunderstorms that will persist into the overnight hours. There should be a lull in the shower activity Wednesday morning but IFR ceilings and visibility may work into east central WI including Sheboygan overnight into Saturday morning on moist ENE winds off Lake Michigan. There is a lot of uncertainty about how far inland and southward these low ceilings and fog will expand.

The next chance for more widespread showers and thunderstorms will arrive in southern WI late Wednesday afternoon and taper off during late evening.

Cronce

MARINE

Issued 1001 PM CDT Tue Apr 14 2026

A stationary front will remain parked over the middle third of the lake into tomorrow, slowly sinking south to the southern end of the lake by Thursday morning. 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 clear the lake as a cold front Friday, before low pressure of 29.6 inches approaches from the west.

Thunderstorms are possible over the southern third overnight into Thursday morning, then Thursday late afternoon and night. Thunderstorm chances return along a cold front Friday night.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ643-LMZ644-LMZ669-LMZ671-LMZ868-LMZ870-LMZ872 until 7 AM Wednesday.