Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
515 FXUS63 KMKX 210359 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1059 PM CDT Thu Aug 20 2026 .KEY MESSAGES... - Scattered showers and thunderstorms (30 to 50 percent chances) with passing cold front mainly Friday afternoon and evening. Gusty winds and small hail may occur. - Small chances (20 to 40 percent) for a shower or storm Saturday afternoon for portions of east central and southeast Wisconsin. && .SHORT TERM... Issued 1100 PM CDT Thu Aug 20 2026 Tonight through Saturday night: Tonight should remain largely quiet outside of a few light showers nudging into the region but despite some PVA pushing through and low level WAA the low level moisture may be too dry initially to bring showers to the ground. Around daybreak Friday we expect some low level moisture to allow for precip chances to increase for a brief period in the morning. The forcing appears to be largely focused along the shortwave with supplementary WAA and better moisture but CAMs do not seem to favor widespread showers in the morning with better chances focused further west closer to the surface front. As the front pushes east moisture seems to improve into Friday afternoon and evening. CAMs seem to favor some development of convection Friday late afternoon on the western half of the CWA with a secondary development potential into the early evening closer to the lake. Given higher instability (>2000 J/kg) and enough shear (30-35kts) we should see a stronger storm or two for a brief period but the lack of better shear should limit the potential to just a few storms at most with the primary concerns being 1 inch hail and brief damaging winds. Quieter conditions overnight Friday into Saturday morning as the surface low pushes out. However, Saturday late morning and afternoon we will likely see a backdoor cold front combined with lake breeze convergence zone in the nearshore region bring additional precip chances for eastern portions of the CWA. There is some uncertainty for this primarily with respect to low to mid level moisture and how widespread it will be but some showers and perhaps a few storms will be possible with this. If we can manage a few storms we could see some become strong given a decent amount of deep layer shear though this differs significantly between the CAMs and synoptic scale models so we will have to monitor those conditions through Friday. This will be worth monitoring Saturday afternoon given some potentially sneaky conditions. Chances will rapidly decrease Saturday evening as we lose instability and forcing pushes out. Kuroski && .LONG TERM... Issued 1100 PM CDT Thu Aug 20 2026 Sunday through Friday: Sunday and Monday will feature high pressure building into the region keeping things dry through Monday. Things have trended overall drier into Tuesday with the high pressure lingering a bit longer with Tuesday night Wednesday becoming our next best chance for showers and storms as and 850mb front and upper level shortwave swing through with some WAA. Still some uncertainty in track and timing but models generally agree on this pushing through bringing precip with likely some storms as well. In addition, deep layer shear appears to be strong in the 40-50kt range which would bring some severe risk if the timing of storms is into the evening. After Wednesday, uncertainty increases quite a bit though in general higher pressure seems to be pushing in with drier conditions overall more likely. Kuroski && .AVIATION... Issued 1100 PM CDT Thu Aug 20 2026 Quiet in large part tonight with VFR conditions generally expected outside of a few showers potentially reducing VSBYs for a brief period. Into Friday morning precipitation chances will increase to the west with uncertainty as to where precipitation with be for any period. Seems like a midday lull is expected in precip with increased chances into the mid to late afternoon and into the early evening. Storms chances are more likely in the afternoon further west with increased chances further east into the evening but continued uncertainty in location. Kuroski && .MARINE... Issued 1100 PM CDT Thu Aug 20 2026 High pressure exits to the southeast tonight with south to southwest winds developing. Theses winds will increase for Friday, along with shower and thunderstorm chances, as low pressure around 29.8 inches moves across the region and drags a cold front through Lake Michigan. Gusty winds will then shift to the northwest later Friday night into Saturday after the front exits. Another high pressure system around 30.2 inches is expected to build into the region later this weekend, which may maintain gusty northerly winds as it moves in. Kuroski && .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