141 FXUS63 KMKX 060604 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 104 AM CDT Sat Jun 6 2026 .KEY MESSAGES... - Scattered thunderstorms are possible through the night, mainly west/south of I-90/94. - A very humid airmass will return Monday and Monday night ahead of approaching low pressure with widespread showers and scattered thunderstorms forecast. - Hot and humid conditions expected mid to end of next week with some potential for Heat Advisory conditions late next week. && .SHORT TERM... Issued 104 AM CDT Sat Jun 6 2026 Overnight through Saturday Night: The east-west broken line of storms will continue to slide southward and exit southern WI between 1 and 2 AM. There is one area of additional storms that are developing between La Crosse and Wisconsin Dells. This is associated with the back edge of a weak shortwave trough sliding through southern WI. The vorticity advection with that feature will help whatever ongoing storms progress into northern IL around daybreak. The main thing we need to watch overnight is for training storms. With precipitable water around 1.5 inches, the storms are efficient rain producers. High pressure will return to the Upper Great Lakes on Saturday (today). We can expect mostly sunny skies and warmer temperatures than yesterday, with highs in the mid 80s. We will still be within the warm and humid air mass with dewpoints in the 60s. The lakeshore will see some relief from from the heat in the afternoon with a lake breeze, but the lake breeze is not going to make it very far inland until the evening. Temps will drop into the 50s for east central and southeast WI Sat nt as drier air briefly moves in. Sunday through Monday: A closed upper low that will be over Texas today will make its way into the Plains on Sunday. The position of this upper low as it approaches the Upper Midwest will draw moisture up from the Gulf and we can expect widespread showers with thunderstorms over southern WI on Monday. They should spread in Sunday night and exit Monday night, although the movement of this weak upper low has uncertainty. This should bring another soaking rain. There could be a few strong storms with this system on Monday, given the negatively tilted upper trough, but the overall system lacks the strong synoptic forcing for a bigger severe event. Cronce && .LONG TERM... Issued 104 AM CDT Sat Jun 6 2026 Tuesday through Saturday: Broad low pressure in the Great Plains will continue to pivot 500 mb shortwaves northeastward through the Great Lakes region Tuesday and Wednesday, leading to on and off thunderstorm potential (20-30% chances). Meanwhile, stiff southwesterly winds will develop on Wednesday, bringing a warm, humid airmass into southern Wisconsin. Expecting highs in the low 90s, with high temperatures reaching all the way to Lake Michigan as southwest winds keep the lake breeze offshore. Thursday, low pressure ejects into the Canadian Prairies and brings an occluded warm front through southern Wisconsin. This is a potential trigger for additional storm development in the afternoon (~35%), which may prevent temperatures from rising as dramatically as Wednesday. However, highs in the upper 80s to near 90 degrees are expected as southwest winds continue to bring in plenty of warm, moist air from the Gulf. Thunderstorm potential continues through Thursday night (20-35%) as winds shift northwesterly and bring in upper 60s for the overnight hours. Winds shift back to southwesterly Friday as low pressure lifts into northern Ontario and additional low pressure develops in the central High Plains. Heat and humidity will increase again, with heat index values potentially rising into Heat Advisory levels. Pop-up thunderstorms are possible, but confidence is low at this time (15-20%). Friday night, expect low pressure to eject into the Plains. Model discrepancy develops as to the path this low takes, but either solution (northern would result in more cloud cover and less warming, southern would result in easterly winds off Lake Michigan) would lead to a respite in high temperatures with the most likely solution in the mid-80s. MH && .AVIATION... Issued 104 AM CDT Sat Jun 6 2026 Storms will gradually shift southward into northern IL overnight. This includes the additional development between La Crosse and Wisconsin Dells that may affect MSN and JVL. Gusty winds and small hail are the threats with these isolated storms. Ceilings within the storms may briefly drop to MVFR, but otherwise VFR conditions are expected through Saturday. Light northerly winds will develop Saturday, with a lake breeze in the afternoon that will shift inland during the evening. Marine fog is possible later Saturday into Saturday night for lakeshore areas. Cronce && .MARINE... Issued 104 AM CDT Sat Jun 6 2026 Broad low pressure will move from Lake Superior into eastern Ontario tonight, bringing a cold front through Lake Michigan late tonight. Southerly winds this evening will allow for continued warm air over cold waters and dense marine fog over the northern half of the lake through Saturday morning. This may need to be extended. The cold front from the low pressure will produce storms across the southern open waters into early Saturday morning. Winds will shift northwesterly behind the cold front, but will remain light. Fog will gradually lift through the afternoon hours Saturday, but may return Saturday night. High pressure builds across the region Sunday, bringing lighter and variable winds through the day. Low pressure develops in the Great Plains Monday, bringing south- southeasterly winds through at least midweek. Additional chances for thunderstorms develop Monday and Tuesday. Cronce && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ868 until 1 PM Saturday. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, X, and YouTube at: www.facebook.com/NWSMilwaukee www.x.com/NWSMilwaukee www.youtube.com/NWSMilwaukee