Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
205 FXUS63 KMKX 161639 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1139 AM CDT Fri Aug 16 2024 .KEY MESSAGES... - Numerous thunderstorms developing this afternoon with the main window from 21Z-02Z. Small hail and gusty winds expected but a few severe thunderstorms are possible. - Showers likely with scattered storms for Sat as a cold front moves through S WI. && .UPDATE... Issued 1139 AM CDT Fri Aug 16 2024 MLCAPE will continue to build toward 2000 J/KG this afternoon ahead of a weak sfc trough, but well organized shortwave trough approaching from S MN. The n-s line of storms over west central WI is currently in the vicinity of a sfc trough but also fairly strong PVA. As the w-e vorticity maximum over srn MN becomes oriented more n-s across srn WI later this afternoon, numerous showers and storms will result. The main window will be from 21-02Z and is well depicted on the HREF. There may be earlier isold development north of MKE where deeper low level moisture and less capping is present. The effective shear will remain 20-25 kts this afternoon but still enough for storm maintenance and organization, thus cannot rule out a few SVR storms with large hail and damaging winds. The sfc low will move across Lake MI this evening reaching srn Lake Huron by 00Z Sun. Its cold front and another vorticity maximum will move through srn WI on Sat. 50-70 percent chances for showers and storms are forecast for ern WI with lesser chances to the west. 500 mb heights will then be rising Sat nt- Sun bringing a return of some sunshine for Sun, but still a slight chance for a shower over sern WI. Gehring && .SHORT TERM... Issued 336 AM CDT Fri Aug 16 2024 Today and Tonight: First, any ground fog should dissipate by 9 AM. Surface front will move through southern Wisconsin today and it will be a focus for convection by mid afternoon. MCAPE will linger, as best moisture convergence shifts east by early this evening. Most locations will not avoid rain, and most of the rainfall should occur between 21Z and 01Z (Sat). The storms should move rather quickly to the southeast during this time frame. Instability parameters also support potential for small hail until early this evening. Severe thunderstorm potential looks minimal (less than 20%) at this time. Otherwise, storms will be out of the forecast area by mid to late evening, but models hold onto the low level moisture. Thinking is that it will remain mostly cloudy tonight with a breezy northwest wind. KPL && .LONG TERM... Issued 336 AM CDT Fri Aug 16 2024 Saturday through Thursday: Mid and upper level low will sit over the Great Lakes Saturday into Saturday night with cyclonic flow over Wisconsin. Although the best surface features will be well south and east of the forecast area by this time, there will still be scattered showers (30-50%) and a few thunderstorms possible by Saturday afternoon. Aiding these showers will be decent mid level lapse rates with colder air lingering aloft. Thinking now that any convective elements will diminish later Saturday evening with gradual clearing over southern Wisconsin. Saturday night will be cool and breezy. Synoptic scale pattern then begins to change on Sunday with heights building aloft. Still could have a buildup of convection by Sunday afternoon, but expecting little or no rain at this time. If anything, will keep low PoPs along the lakeshore to the open waters of Lake Michigan. Otherwise, another cool night on Sunday with mostly clear skies. The remainder of the extended forecast period looks pretty straightforward with dry, northwest flow aloft and gradually warming temperatures (near normal). This benign weather pattern with surface high pressure should continue into Wednesday and Thursday. KPL && .AVIATION... Issued 1139 AM CDT Fri Aug 16 2024 MVFR Cigs transitioning to sct-bkn040 this afternoon. Numerous showers and storms expected from 21Z-01Z. Low Cigs of 600-1900 feet developing from west to east across S WI this evening. The low Cigs will continue through Sat AM then MVFR Cigs for the early afternoon becoming sct-bkn035. Scattered showers and storms expected for Sat. Gehring && .MARINE... Issued 1139 AM CDT Fri Aug 16 2024 Low pressure near 29.7 inches over north central Minnesota will slowly move across northern Wisconsin this afternoon and tonight, and to southern Lake Huron by the end of Saturday. Modest south winds today will become westerly late this evening for the south half, and variable winds for the north half. The winds will then transition to breezy north to northwest winds for the weekend. The winds will gradually weaken early next week as high pressure arrives over the lake by Tuesday. Scattered thunderstorms can be expected over the lake today into Saturday evening. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee