FXUS63 KMKX 240532 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1232 AM CDT Mon Aug 24 2026 .KEY MESSAGES... - Crisp, fall-like conditions tonight. Some fog is possible after midnight. - Comfortable & pleasant afternoon weather conditions today through Tuesday & Thursday-Friday. - Windows for showers & thunderstorms Tuesday night through Wednesday & next weekend. && .SHORT TERM... Issued 1232 AM CDT Sun Aug 23 2026 Tonight through Monday Night: With high pressure overhead, skies are clear and winds are light. Temperatures in the low 50s to low 60s across southern Wisconsin will continue to fall throughout the night with overnight lows expected to fall into the upper 40s to mid 50s. Generally warmer temperatures will be along Lake Michigan. A nice crisp night and a taste of fall for those of us that are looking for it. As temperatures fall there is a potential for fog to develop tonight but there in some uncertainty in how much fog will develop. Available moisture will be the one competing factor for whether or not fog develops. If moisture is lacking then dew is more likely to form than fog. Still a bit to early to tell, but should be something that shows itself in the next couple of hours or so as the dew point depression drops to 1-2 degrees at multiple sites. Any fog that develops is expected to burn off/mix out shortly after sunrise. High pressure will slowly begin to shift east of the state, Monday. Fair weather cumulus clouds are likely to develop again this afternoon. Likewise under the light winds, a lake breeze is should develop and a few miles inland. Quiet conditions are expected through Monday night. As winds become southwesterly behind the departing high, WAA should slowly return ahead of the next incoming system for Tuesday. Patterson && .LONG TERM... Issued 1232 AM CDT Sun Aug 23 2026 Tuesday through Sunday: Heading into Tuesday, high pressure will be moving east into the Mid Atlantic and New England states as a low pressure system travels across southern Canada into the northern Great Lakes Region. The upper level trough is expected to follow the exact same track as this system becomes stacked. The surface low is expected to occluded as it moves east before reaching the Great Lakes Region. For southern Wisconsin, the best chance for precipitation is expected to be with some WAA behind the warm front and with the passage of a cold front. There is some uncertainty on how much if any rain/storms we get with the push of WAA and any we do get will just eat away at any instability we would have gained in the afternoon/evening. The main concern here is the lack of any low level forcing. As temps and moisture increases diurnally there will be instability, but nothing to force convection. Which reflects why there are only a few model runs with any after convection so low chance but non zero. Especially if one shower goes, its outflow could trigger many more. Now with the passage of the cold front there is expected to be better upper level lit from the trough, but the timing of this looks to occur during the overnight hours into Wednesday late morning. This separates the best instability with the best lift and forcing. So while rain and storms are expected due to this confidence on any strong to severe storms are low. Its a low but non zero chance situation. Shear looks to be the one category that is persistent from the WAA to the passage of the cold front in support of stronger storms. It will just come down to timing and when our best forcing and instability resides. The low pressure system and front are expected to clear southern Wisconsin by Wednesday afternoon. High pressure is then expected to return to southern Wisconsin from Manitoba on Thursday and Friday. This area of high pressure will be exciting to the east Friday night as another low pressure system approaches from the Plains. This will bring rain chances back for the weekend. An upper level trough is expected to move through Canada with a few short wave troughs moving through the larger flow across the Great Lakes Region. These storms chances seem to largely be driven by the shortwave aloft and the LLJ. Which when aligned can lead to rain and storms, but there are some meso scale features that can throw that off or take a day of storm potential and turn it into mostly with little lightning. A lot of it will come down to where the best shear and instability reside which global models seem to be washing out and spreading out over a generous portion of the state. This is then reflected in the low chances around 10-30%. More details will shake out as we get closer to the weekend. Patterson && .AVIATION... Issued 1232 AM CDT Sun Aug 23 2026 Largely VFR conditions through the period. With clear skies and light winds tonight, there is a small potential for lower ceilings and visibilities for any fog that develops after midnight. There is uncertainty in how widespread the patchy fog could become so kept mentions out of the TAFs for the time being. If fog develops visibilities could fall to 2-4 SM. Terminals in low lying areas or river valleys (LNR and JVL) will have the best potential for fog development. VFR conditions are expected to return shortly after sunrise. Fair weather cumulus clouds are expected to return late morning through the evening Monday. The few to scattered cloud deck is expected to be around 4-6 kft. Light and variable winds tonight will become light northwesterly winds Monday. A Lake breeze is expected to develop during the early evening hours which will turn winds to the northeast then east for lakeshore terminals. Light and variable winds are expected again Monday night. Patterson && .MARINE... Issued 1232 AM CDT Sun Aug 23 2026 Low pressure across eastern Ontario will linger through Monday night which will result gusty winds across the northern third of the lake during this time. Gusts will approach gale force at times. As high pressure moves overhead Monday winds will become light and variable across Lake Michigan. South to southwest winds will set up across the lake as the high departs and ahead of the next incoming low pressure system. The low pressure system is expected to move through the northern Great Lakes Region and drag a cold front across the Lake Wednesday afternoon. Rain and thunderstorms will be possible across the entire lake from Tuesday evening through Wednesday afternoon. A brief period of Small Craft Conditions will be possible Tuesday afternoon and evening ahead of the approaching low pressure system. Patterson && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ 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