Area Forecast Discussion

KEY MESSAGES

- Hot and humid conditions continue through Monday. A Heat Advisory is in effect through 9 PM CDT tonight. Additional Heat Advisories may be needed Monday, especially in southwestern Wisconsin.

- Severe storms are expected late this evening through tonight. Late this evening into early tonight, a line of storms may progress southeastward with all hazards possible. Late tonight into early Monday morning, a second line of storms is expected to progress southward through the region with the primary hazards wind and heavy rain. Isolated hail and an isolated tornado cannot be ruled out.

- Monday, a cold front will bring final chances for storms. All hazards are possible with this activity, but intensity will depend on how late storms linger Monday morning.

- High swim risk may develop early Tuesday morning and continue through Tuesday evening along all Lake Michigan beaches due to high waves and currents expected.

SHORT TERM

Issued 447 PM CDT Sun Jul 26 2026

Tonight through Monday night:

Temperatures will continue to climb for the next few hours as cloud cover continues to scatter out, with the Heat Advisory remaining in effect through 9 PM CDT tonight for all of southern Wisconsin away from Ozaukee and Sheboygan Counties. Lake breeze was able to establish itself firmly under morning to early afternoon cloud cover, so the majority of Milwaukee County has remained cooler than nearby counties. Still, with solar heating continuing into this evening and clouds scattering out, not enough confidence to cancel as western portions of the county may still see reach 100 degree heat indices.

Monitoring a broken line of storms developing in northern Minnesota and Wisconsin as the next target for severe weather. CAMs are painting two distinct outcomes from these storms. The first would be for the storms to encounter the EML and decay, remaining scattered and struggling to organize as they move southward into southern Wisconsin. Severe storms would be possible with this solution with remaining CAPE over 3000 J/kg and PWATs over 1.5 inches (wet microbursts and hail potential). The other solution indicates organization into a strong cold pool over northern Wisconsin and becoming a strong MCS moving southward through southern Wisconsin. As 18Z runs trickle in this afternoon, this solution appears to be favored by the majority of CAMs, putting isolated QLCS tornadoes, hail, and wind as core threats between 9 PM and midnight.

After midnight, LLJ develops, with the nose pushing into southwestern to central Wisconsin. This will serve as the focal point for additional storm development. Increasing PWATs (over 1.75 inches) and remaining MUCAPE (2000-3000 J/kg) will allow for these storms to produce wet microbursts as they develop. If clusters are able to organize, an additional MCS threat would develop with QLCS tornadoes becoming a possibility. Regardless of severity, heavy rain will become a threat with high rainfall rates and potential for multiple rounds of storms over the same areas. Early Monday morning, with the environment becoming worked over, expect primarily a heavy rain and lightning threat before storms taper off mid-morning.

Hot and humid conditions continue through Monday. However, temperatures and therefore heat index values may stay below Heat Advisory criteria due to the previous night's rainfall and lingering cloud cover Monday afternoon. Southwestern Wisconsin sees the best chance of 100 degree heat index values, with potential for heat index values in the 90s elsewhere.

Monday afternoon, a cold front will progress southeastward through the region. Again depending on previous cloud cover and lingering boundaries, a final period of severe storms is possible. Confidence in impacts is low, but with increasing shear all hazards are on the table provided afternoon destabilization occurs.

Monday night, final rounds of storms exit the area, with northerly winds increasing and producing building waves at Lake Michigan beaches by Tuesday morning. Lows in the mid-60s.

MH

LONG TERM

Issued 447 PM CDT Sun Jul 26 2026

Tuesday through Sunday:

High swim risk may develop Tuesday and continue through Tuesday night at Lake Michigan beaches due to northerly winds and building waves and associated currents. Use caution and stay out of the water!

Dry conditions and more seasonable temperatures return Tuesday into Thursday with highs in the 80s. Friday through Saturday, low pressure developing in the Plains will bring the next chances for storms to the region as shortwaves ride through the decaying ridging. Expecting a return to high pressure on Sunday.

MH

AVIATION

Issued 447 PM CDT Sun Jul 26 2026

VFR conditions and light southwesterly winds are expected to dominate the rest of this afternoon through this evening. Late this evening into tonight, a line of storms is expected to develop and progress southeastward. All hazards are possible within this band, with damaging winds being the main concerns. Late overnight, an additional line of storms will develop, with wind and heavy rain the main concerns. MVFR ceilings and visibilities are possible within these storms. Storms will taper off into Monday morning, with VFR conditions expected thereafter. Late Monday afternoon, a cold front will shift winds to northerly and bring additional scattered thunderstorms to the region.

MH

MARINE

Issued 447 PM CDT Sun Jul 26 2026

Patchy dense fog is expected in portions of the central to northern Lake Michigan through tonight and potentially Monday as warm moist air moves northward.

Severe storms are possible tonight within that warm air mass across Lake Michigan. Waterspouts, very strong winds, and hail are possible with these storms. Storms will move north to south across the lake late tonight. Monday, expecting a cold front to progress north to south across the lake in the afternoon hours. This will bring the next chances for severe weather, with strong winds and hail the main threats. Northerly winds are expected behind the front, with gusts around 30 kt expected. Gusts to gale force cannot be ruled out as low pressure deepens to 29.5 inches over the eastern Great Lakes Tuesday. Winds will remain northerly through Wednesday as high pressure around 30.0 inches builds into the northern Great Lakes, then will become lighter and more variable into Thursday and Friday as high pressure builds overhead.

MH

MKX WATCHES / WARNINGS / ADVISORIES

WI...Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ056-WIZ057-WIZ058- WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068- WIZ069-WIZ070-WIZ071-WIZ072 until 9 PM Sunday.

LM...None.