textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Scattered, non-severe showers & storms possible through the predawn hours. Flood Watch remains in effect in Sauk County through 7 AM.

- Chances (~30-50%) for thunderstorms this afternoon & evening (~12-8 PM) if enough instability recovery occurs in the wake of morning showers/storms. A few severe storms with gusty winds and hail are possible.

- Additional batches of showers and storms continue late tonight through Sunday. Keep up with the forecast if planning to be outdoors.

- Trending quieter early next week.

SHORT TERM

Issued 200 AM CDT Fri Jul 3 2026

Today through Tonight:

Synopsis/Mesoanalysis: Regional radar mosaics remain busy tonight following an evening of strong to severe storms across southern Wisconsin. Said storms laid down an elongated outflow boundary, which currently stretches from the Chicago metro to just south of the Des Moines, Iowa vicinity. Thanks to a southwesterly low level jet in place regionally, ascent up & over the outflow has allowed convection to blossom to the north/cool side of the boundary from Iowa across northern Illinois. Some of this activity could leak north into southern Wisconsin through the remainder of the overnight hours, particularly to the south of I-94 and US-18. Further to the west over the Central Plains, additional widespread convection is ongoing over Nebraska. While these storms will remain well west of the area through tonight, high-res forecast guidance is hinting at an affiliated remnant shortwave/MCV crossing the region this afternoon. Whether this feature will be able to trigger storm development will depend on air mass recovery in the wake of predawn showers/storms regionally, with forecast trends being monitored through the rest of this morning. In the event storms were to form this afternoon, a few would be capable of producing gusty straight line winds. Additional showers and storms are possible during the predawn hours Saturday. With clouds & areas of showers/storms around the region, temperatures are expected to remain below heat headline thresholds today.

Rest of the Overnight: Will be monitoring convective trends over Iowa and northern Illinois as storms regenerate over the top of outflow boundaries laid down by earlier evening convection. Expect that development will continue over these regions through the remainder of the overnight hours given a persistent southwesterly low level jet & attendant overrunning. Whether activity manages to propagate further north/into southern Wisconsin remains more uncertain, as the low level air mass remains worked over in the wake of multiple batches of convection last evening. Best convective potential will be along/south of I-94 & US-18, where elevated instability values remain a touch higher compared to further north. Not expecting severe weather in the event convection makes it back into the area, though heavy downpours would be possible. Have maintained the existing Flood Watch over Sauk Co given antecedent wet conditions & convective chances. If appreciable precip stays south of the region through the rest of the overnight, watch will be allowed to expire as scheduled at 7 AM.

This Afternoon & Evening: Forecast uncertainty increases as a remnant shortwave/MCV from storms currently over the Missouri Basin moves across the region. If sufficient destabilization can occur in advance of the feature, it could help trigger scattered storm development during the ~12-8 PM timeframe, with a few severe storms with gusty winds and hail possible. If, however, morning convection over Iowa/Illinois/southern Wisconsin holds better instability to the south of the region, storm coverage would be minimal. Will thus be monitoring trends closely, as what storms do through the morning hours will go a long way in determining what the radar looks like come afternoon. Will continue to provide forecast updates through the morning.

Tonight: Will be watching for more thunderstorms during the predawn hours as one or multiple clusters of convection move into the Mississippi Valley from the Plains. Expect that convective intensities will be waning as these storms approach, likely limiting severe potential. Will continue to monitor trends and provide updates through today.

Quigley

LONG TERM

Issued 200 AM CDT Fri Jul 3 2026

Independence Day through Wednesday:

The upper ridge over the eastern CONUS will gradually diminish as mid level westerlies win out as they head east of the Great Lakes region Sunday and Monday. Unfortunately, our region will remain in a battle zone of sorts for Independence Day into Sunday. From a large scale pattern perspective, it is prudent to expect an convective system or two. However the timing and details will be heavily determined by how the mesoscale is altered by convective behavior and remnant boundaries Friday and Friday night. At this time, from a large scale pattern perspective, it appears the better rain chances shift east of the area on Sunday, but this will have to be closely monitored day to day.

Early next week, ensemble consensus is for a mid level ridge to build over the Rockies, nudging our upper level pattern into northwest flow. This will deliver typical July conditions with lows in the 60s and highs in the 80s. Small ripples from time to time are to be expected in this northwest flow pattern, though timing these individual waves is a futile exercise. Bottom line, there will be a good amount of dry time, and intermittent chances for showers/storms with any ripples.

Gagan

AVIATION

Issued 200 AM CDT Fri Jul 3 2026

VFR flight categories prevail through large portions of the period at all fields, with SCT to BKN clouds based near FL040. Periods of showers and storms will bring occasional categorical reductions, with prevailing VFR returning in the wake of departed convection. Some storms could produce gusty winds and hail.

Quigley

MARINE

Issued 200 AM CDT Fri Jul 3 2026

High pressure around 1020 mb will remain parked over the Ohio Valley and Appalachian Mountains into tonight. Meanwhile, a trough of low pressure will remain over the Great Plains through tonight. A weak low pressure area may then organize and slowly move across Wisconsin and Lake Michigan from Saturday afternoon into Sunday, or pass farther south across Illinois into the Ohio Valley. Modest south to southwest winds will persist today becoming a bit lighter tonight and Friday. Light to modest winds are then forecast for the weekend, but with some uncertainty on wind direction given low confidence in the track of the low. A stormy period is expected for central and southern Lake Michigan through the weekend. Patchy marine fog will be possible at times as warm and humid air flows over the relatively cooler lake.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES

WI...Flood Watch...WIZ056 until 7 AM Friday.

LM...None.