


Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
304 FXUS63 KMKX 160241 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 941 PM CDT Wed Oct 15 2025 .KEY MESSAGES... - Light rain is possible (20-40%) Thursday night into Fri morning. - Better chances (60 to 80 %) of showers and a few thunderstorms along a cold front late Friday night through Saturday. The forecast progression of this front is trending slower. && .UPDATE... Issued 940 PM CDT Wed Oct 15 2025 High pressure is centered over Lake Superior this evening, resulting in generally east to northeast winds across southern Wisconsin. The prevailing synoptic flow has allowed drier boundary layer air to work in from the northeast, which has been most evident in increased cloud bases across southern Wisconsin. Moisture remains sufficient for cloud cover at and above 900 mb, with forecast soundings showing said moisture remaining through the overnight. Thus anticipate at least broken clouds to stick around across the majority of southern Wisconsin tonight, resulting in low temperatures only a few degrees cooler than current obs in most locations. Will be monitoring for fog development over east-central and southeast Wisconsin, though formation will be highly dependent on any decoupling. Trends will be monitored through daybreak. Responding to increasing upper divergence & attendant warm advection in the 925-700 mb layer, showers and isolated thundershowers are starting to fill in across northwest Iowa. Expect development to continue through the overnight, with activity moving east-northeast through dawn. May see some of this activity clip areas primarily north & west of Madison after sunrise. Additional chances for rain enter the forecast Thursday afternoon and evening. Quigley && .SHORT TERM... Issued 351 PM CDT Wed Oct 15 2025 Tonight and Thursday: The pressure gradient will continue to ease this evening into tonight as high pressure near central Lake Superior continues east. Low clouds over Wisconsin late this afternoon and should persist into the overnight hours for much of the state. Ceilings are very slowly diminishing from the northeast to the southwest, but at the pace its at and the placement of the front in Iowa will likely prevent southwestern Wisconsin from clearing at all. Given this there is some uncertainty in how much areas will clear overnight into Thursday. Areas that do have clear skies will have the potential for fog to develop. Not anticipating any dense fog as winds will be light but not calm and skies may not be perfectly clear. Eastern Wisconsin has the best potential for fog. Any fog that does develop will burn off shortly after sunrise. Tonight the LLJ will also move back into Minnesota and west central Wisconsin. The LLJ should shift northward overtime and be set up over northern to north central Wisconsin by Thursday morning. A weak shortwave will move over the upper level ridge during this time, which will kick off additional showers across the state. For southern Wisconsin, all of our rain will be driven by the weak lift from the shortwave which should give us scattered rain showers. The best chances for rain are across central and northern Wisconsin where the LLJ will be situated. These areas will also have the best potential for any lightning. Only the far northwestern counties (Marquette and Green Lake) have any real chance for a rumble of thunder/flash of lightning, but chances are very low. Did increase the POPs just a bit across southern Wisconsin to pull in some 20-40% POPS for Thursday which are mainly across the northwestern portions of our area. CAMs in particular dont seem to be handling the weak lift scenario we are in very well. This is pretty normal for weak ridge riders and has already shown its hand into todays rainfall across southwestern WI and north central Iowa. Southeast WI may not see any rain from this system. Patterson && .LONG TERM... Issued 351 PM CDT Wed Oct 15 2025 Thursday night through Wednesday: As we head into Friday the upper level ridge is expected to move eastward out of the state. High pressure at the surface in the eastern Great Lakes Region will move into the New England States. Wind will turn to southerly across the state as this high moves away. Meanwhile a strengthening trough will swing from the Rockies northward toward the northern Great Lakes Region/Quebec. The sfc low will develop in the lee of the Rockies and should track from there to the northern Plain and then into Canada heading toward James Bay. An associated cold front will move east into Wisconsin late Friday night into early Saturday afternoon bringing widespread chances for rain. Guidance continues to ever so slight shift this frontal passage later in time (slowing it down). Regardless a band of showers and some thunderstorms should move through the area along the front. WAA out ahead of the front and strong Fgen along it should produce more widespread rain and thunderstorms. Given this can`t rule out the potential for a stronger storm or two if the front continues to have a later the progression of the front. This would cause storms to develop during peak heating Saturday. Deep layer bulk shear is good and may not take much instability to get some stronger storms with gusty winds to occur. Still uncertainty with this potential, so keep up with the forecast. The precipitation should end fairly quickly behind the front, as strong cold air advection on northwest winds pushes into the area by Saturday night. A rather deep trough should then shift through the region Saturday night into Sunday. Some lingering moisture may result in scattered showers at times during this period. Temperatures should cool down to near or a little above seasonal normal values Saturday night into Sunday. Trends beyond this point are very uncertain, so will leave NBM PoPs and temperatures unchanged in the forecast. Patterson && .AVIATION... Issued 940 PM CDT Wed Oct 15 2025 High pressure is centered near Lake Superior this evening, resulting in generally east-northeast winds at all terminals. Said winds have allowed drier air to begin working into the region from the northeast, with VFR flight categories becoming established at all fields over the last couple hours. Will be monitoring for FG development near Lake Michigan, where skies will attempt to clear and winds will lighten during the predawn hours. Confidence remains too low to justify any mentions in the 03Z update, though trends will be closely watched through tonight. Currently ongoing over northwest Iowa, -SHRA will continue to increase in coverage to the west of the region overnight as upper level lift increases across the Upper Mississippi Valley. Majority of precip should remain north and west of the area through sunrise, though impacts can`t be ruled out following daybreak at MSN. Have thus inserted PROB30 -SHRA groups in the 00Z update, with later updates to the MSN TAF being made as trends warrant. Additional -RA development is anticipated over north-central Wisconsin Thursday afternoon, with the southern edge of activity expanding into the region Thursday evening. Have added PROB30 -RA groups in the 00Z update at SBM and MKE given this expected development. Quigley && .MARINE... Issued 351 PM CDT Wed Oct 15 2025 High pressure will continue to move east across Lake Superior through tonight. Light east to northeast winds this evening will become southeasterly Thursday morning as the high continues to pull away. Thursday afternoon southeast winds will become breezy and remain into Friday morning as low pressure in the northern Plains moves toward James Bay. This low will deepen as it moves northeast and an associated cold front will move across the Lake Saturday. Gusty south wind are expected over the lake ahead of the cold front with a few gale force gusts possible Friday afternoon through Friday night. This low will further deepen leading to strengthening northwest winds behind the front for Saturday night into Sunday. Another period of gales will be possible behind the front. 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