Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
680 FXUS63 KMKX 220237 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 837 PM CST Fri Nov 21 2025 .KEY MESSAGES... - Patchy fog & freezing fog possible tonight in the Wisconsin River Valley. - Temperatures several degrees above normal this weekend into early next week. - 80-90 percent chance of rain Monday night, lingering into Tuesday. - Below normal temperatures move in Thanksgiving Day onward as polar air arrives from Canada. && .UPDATE... Issued 840 PM CST Fri Nov 21 2025 Surface observations show a ridge of high pressure quickly advancing into southern Wisconsin this evening. Arrival of the surface ridge has allowed clouds to scatter out across most of the area, with most locations north of I-94 and US-18 reporting mostly clear skies. The clear skies, combined with decoupling boundary layer winds, have allowed for efficient radiational cooling to occur post-sunset, with a scattering of stations having fallen below freezing as of 8 PM. Anticipate that temperatures will continue to fall through the overnight period, with most locations away from Lake Michigan seeing temps falling into the low-mid 20s by daybreak. Can`t rule out a few lows in the teens, particularly in low-lying areas susceptible to cold air drainage. Dew points should also fall steadily as low level subsidence increases ahead of the encroaching surface ridge, maintaining some separation between surface temps and moisture through the overnight period in most locations. Nevertheless, can`t rule out some shallow & patchy fog in low-lying spots along/west of the Kettle Moraine through sunrise. Greatest potential will be in the Wisconsin River Valley, where visibilities have already started to drop this evening. Given the sub-freezing surface temperatures, a few slick spots would be possible in any persistent areas of patchy fog. Slow down if encountering patchy fog through daybreak tomorrow morning. Quigley && .SHORT TERM... Issued 248 PM CST Fri Nov 21 2025 Tonight through Sunday night: Mostly cloudy skies via high clouds will prevail mainly from MSN to MKE and swd as a wave train of vorticity maximums track west to east from IA to srn WI. These high clouds will decrease early in the evening. The more organized shortwave trough over ne KS and nrn MO will move across the Ohio Valley tnt-Sat AM. Surface ridging will remain over srn WI through 15Z Sat with good radiational cooling conditions leading to low temps in the 20s for tnt. For Saturday afternoon and Sunday a Canadian shortwave trough in nwly flow aloft will track from the nrn Great Lakes to the Mid Atlantic States. At the surface, a trough/cold front will approach Sat afternoon with swly winds and warm advection ensuing. A band of cloud cover will occur with the QG lift but no precipitation is expected at this time. The weak cold front will then pass Sat nt. High pressure will then follow for Sun afternoon and night. Relatively mild temps will continue for the weekend. Gehring && .LONG TERM... Issued 248 PM CST Fri Nov 21 2025 Monday through Friday: Clouds will increase Monday with rain becoming widespread Mon nt as a shortwave trough tracks from the central or srn high plains toward IL and srn WI. This shortwave trough will shear out as it approaches due to a more dominant upper wave approaching the Upper MS River Valley in the nrn jet stream. Nevertheless, warm, moist advection, Fgen, and PVA will bring rain to the region. A sfc low associated with the dominant upper wave will then track across nrn WI or Lake Superior either Tue or Wed with its polar cold front to arrive over srn WI Tue afternoon. The cold advection will initially be gradual but increase into Wed and Thanksgiving Day as the low moves into Quebec. Temps will fall below normal by Thanksgiving Day and last at least into Friday. Gehring && .AVIATION... Issued 840 PM CST Fri Nov 21 2025 VFR flight categories prevail through tonight as high pressure moves into southern Wisconsin. The high`s arrival will result in light/variable surface winds at all terminals by midnight, with conditions lasting through daybreak. Winds will shift out of the southwest during the day Saturday as low pressure moves into the Northern Plains. Quigley && .MARINE... Issued 248 PM CST Fri Nov 21 2025 Light to modest northwest winds will continue through this evening as low pressure of 29.5 inches lingers in the Hudson Bay area, and high pressure of 30.1 inches builds into Wisconsin. High pressure builds overhead late tonight into Saturday morning, bringing light and variable winds. For Saturday afternoon, expect breezy southwest winds to develop as weak low pressure of 29.7 inches progresses through Lake Superior. Winds shift northwesterly Saturday night into Sunday with the passage of a cold front. High pressure briefly returns Sunday night, followed by modest south winds developing Monday and Monday night, as low pressure moves into the Upper Mississippi River Valley. Gehring && .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