textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Rain is looking likely from Madison to Milwaukee and south to the IL border for Sunday afternoon and evening. Around one half inch of rain is expected south of the I-94 corridor.

- Moderate to high swim risk expected for Lake Michigan beaches Monday. Keep out of the water and away from dangerous areas like piers and breakwalls!

- On and off thunderstorm chances Tuesday through Thursday, and potentially again next weekend.

- Below normal temps continue.

SHORT TERM

Issued 1253 AM CDT Sun Jun 21 2026

Today through Monday night:

Patchy fog early this morning will burn off quickly as the sun rises, even with high cloud cover increasing. By mid-morning, expecting northeasterly onshore winds to increase and steady rainfall to spread west to east generally along and south of the I-94 corridor. More isolated to scattered rainfall is expected to the north of the corridor, with the NAM family still indicating the farthest north trajectory all the way through Marquette/Green Lake/Fond du Lac/Sheboygan during the late afternoon to evening hours. However, with a known moisture bias, tend to lean toward the isolated shower solutions for those areas. In addition, global models are still showing dry conditions across southern Wisconsin, which leads to the continued hedging against higher PoPs along and north of the I-94 corridor. Very minimal (~100-200 J/kg) MUCAPE exists in the 0 to -20 C portion of the column right along the WI/IL border during the late afternoon to evening hours, so cannot rule out an isolated bolt of lightning, but the probability is very low (~10%).

As low pressure makes its closest approach this afternoon into tonight, expecting gusty northeast winds to develop and persist along Lake Michigan counties and far southern Wisconsin. Gusts 20 to 25 mph expected. With rain and onshore winds, expecting temperatures to struggle to exit the 60s, with some areas farther north where sunlight lingers longer seeing highs in the low 70s.

Low pressure exits to the east overnight tonight, with gusty winds continuing and turning more northerly. Moderate to high swim risk is expected to develop along Lake Michigan beaches during the overnight hours, continuing into Monday, with high swim risk generally expected Milwaukee County southward. Stay out of the water during this period, and stay away from dangerous areas like piers and breakwalls! Highs in the 60s are expected near Lake Michigan, gradually increasing westward to the upper 70s in southwest WI. Winds will gradually diminish Monday night, allowing waves to diminish below hazardous levels. Lows Monday night in the low 50s.

MH

LONG TERM

Issued 1253 AM CDT Sun Jun 21 2026

Tuesday through Sunday:

High pressure persists over the Great Lakes region through Tuesday, with low pressure deepening over the northern Plains. Expect southwesterly winds to bring in highs in the upper 70s. Low pressure looks to pivot northeastward into Tuesday night, bringing the next widespread chances for rainfall to southern Wisconsin (60-80%). Lightning will also be expected with this rainfall, but low potential for severe at this time (time of day and lack of LLJ dynamics lead to a very conditional threat, especially with the parent low so far northwest).

Lingering precipitation across the Midwest along a frontal boundary from the northern Plains low then looks to phase with a shortwave from the southern Plains, allowing for cyclogenesis across the Great Lakes and therefore bringing an additional wave of precipitation on Wednesday (60-80%). The timing of this wave looks to be more favorable, with southern Wisconsin remaining in the warm sector. Lightning is expected, and potential for severe may develop during the afternoon hours on Wednesday. Low pressure exits into Wednesday night, with a cold front bringing in one last round of showers and storms. Modeling diverges on whether low pressure continues to bring a final shortwave of precipitation across the region on Thursday, so left in 20-40% PoPs due to uncertainty.

High pressure makes a brief return on Friday, but an active pattern with frequent shortwaves propagating through the southern Plains into the Upper Midwest will continue through the weekend.

MH

AVIATION

Issued 1253 AM CDT Sun Jun 21 2026

VFR conditions expected through the morning hours, with increasing cloud cover between 20,000 and 25,000 ft early this morning. Clouds will begin to lower below 10,000 ft late this morning, with bases around 3500 ft as rain moves in from MSN to MKE southward during the afternoon. Rain will lower visibilities potentially to MVFR, while cloud bases continue to lower to MVFR during the evening hours hours. Areas in central WI may remain VFR throughout the afternoon hours as well before falling during the evening hours. Winds also become easterly and increase midday. Rain will taper off west to east this evening, with winds becoming gusty and turning north-northeast. Ceilings will gradually improve west to east overnight.

MH

MARINE

Issued 1253 AM CDT Sun Jun 21 2026

Low pressure around 29.5 inches currently over the central High Plains will progress eastward into central Illinois this afternoon and evening, bringing increasing easterly winds to the southern half of the open waters. Winds are expected to build waves in the southern Wisconsin nearshore waters, potentially bringing hazardous conditions for small craft. Winds turn northerly and spread northward into Monday morning as low pressure exits into the Northeast U.S. and high pressure around 30.3 inches builds into northern Ontario. Winds remain northerly and steadily diminish Monday night into Tuesday as high pressure builds over the Great Lakes, with light and variable winds expected Tuesday night. Winds shift southeasterly as low pressure develops in the northern Plains on Wednesday, then to northwesterly as a cold front from this low pushes eastward through the open waters. Scattered thunderstorms are also possible ahead of and along with this cold front. Low pressure exits to the east on Thursday, bringing northwesterly winds and a brief return to high pressure.

MH

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.