Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
194 FXUS63 KMKX 060210 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 910 PM CDT Tue Aug 5 2025 .KEY MESSAGES... - Wildfire smoke will create haze and air quality at the Unhealthy for Sensitive Groups level. An Air Quality Advisory is in effect until noon Wednesday. Air Quality is expected to improve from then onwards as light southerly winds deliver cleaner air. - Patchy ground fog and valley fog will be possible again tonight into early Wednesday morning, and may become locally dense. - Heat and humidity gradually return toward the second half of the week, along with shower and thunderstorm chances. && .UPDATE... Issued 910 PM CDT Tue Aug 5 2025 Wildfire smoke continues to linger across southern Wisconsin tonight. Winds will become light and variable again before becoming southerly tomorrow morning. Once southerly winds kick in again some cleaner air will start to move in again. Under the light winds and mostly clear skies tonight, fog will again be possible. Low lying, marshy areas and river valleys will be susceptible for dense fog development. No major changes to the forecast. Patterson && .SHORT TERM... Issued 300 PM CDT Tue Aug 5 2025 Tonight and Wednesday: Quiet and dry weather expected through the Short Term forecast, with the exception of lingering Wildfire Smoke leading to air quality in the Unhealthy for Sensitive Groups level. The WI DNR has issued an Air Quality Advisory that lasts through Noon Wednesday. From then onwards, southerly winds are expected to slowly deliver cleaner air into the region. Similar to this past night, patchy ground fog is expected to develop overnight, and could become locally dense, particularly in low lying marshy areas and river valleys. This fog will burn off within a few hours after sunrise Wednesday, allowing temperatures to climb to the mid 80s under partly cloudy skies. Sheppard && .LONG TERM... Issued 300 PM CDT Tue Aug 5 2025 Wednesday night through Tuesday: As surface high pressure continues a gradual retreat east into the eastern CONUS / Atlantic Ocean and surface pressure troughing continues east of the Rocky Mountains (particularly the northern plains) for the later half of this week, southerly WAA allows the upper level ridge axis to build to our west, with daytime high temperatures gradually climbing Thursday (mid to upper 80s) and Friday (around 90). Chances for thunderstorms (15-30%) are forecast Thursday as a shortwave rides down the crest of the ridge, with the NAM model showing the strongest PVA dynamics with that shortwave (and thus the highest confidence in convection). The NAM Nest model (which is only just now in-range for Thursday) allows scattered thunderstorms to develop over central and southwestern WI through Thursday, resolving only 20-30kts of 0-6km shear, with ordinary and multicell cluster modes, evolving into a broken line of storms that sags south toward Iowa / northwestern Illinois. That said, the NAM Nest and RRFS are the only CAMs in range at the moment, and with the ECMWF / GFS leaning towards a weaker 500mb vorticity maximum, I aim to leave precip chances where they are (15-30%) for Thursday until other CAMs are in range. Dry weather is expected for Friday given the lack of forcing for ascent and the ridge axis passing overhead, with the lack of cloud cover further contributing to the rising temperatures. Currently expecting daytime high temps around 90, dewpoints around 70. Due south winds may allow for a tad of ventilation right along the Lake Michigan shoreline (slightly cooler temps), though the inland extent of this feature should be limited. Chances for showers and thunderstorms rebuild Saturday night into Sunday (20-40% chances) as the upper level ridge drifts east and the corresponding upper level trough digs south toward the northern Great Plains, bringing the jet stream close enough by for occasional jet entrance regions and shortwave troughs to provide chances for convection to initiate. Modest southwest winds abate the lake breeze effect and spread the heat to the shoreline Saturday. With potential for cloud cover (and attendant 25-40% shower and thunderstorm chances) opted to keep Sunday through Tuesday`s high temperature forecast just a few degrees cooler than Saturday. Sheppard && .AVIATION... Issued 910 PM CDT Tue Aug 5 2025 Predominately VFR to MVFR conditions are expected through the period. The one exception will be terminals in low lying areas, marshy areas or river valleys. These terminals like LNR will have the potential for dense fog to develop bringing IFR visibilities around 1-2 SM. Everywhere else patchy ground fog will be possible with visibilities around 6-4 SM. Any fog that develops will burn off shortly after sunrise. Hazy skies and Smoke will continue to linger across southern Wisconsin through tonight. Smoke will gradually begin to mix out and disperse Wednesday as light south to southeast winds develop. Dry weather is expected again through Wednesday. Patterson && .MARINE... Issued 300 PM CDT Tue Aug 5 2025 Light and variable winds are expected across the lake until the high pressure shifts eastward into the New England states later this week. Light southerly winds become established Thursday as low pressure develops over the northern Great Plains, with showers and thunderstorms possible later Thursday through Thursday night over the northern two thirds of the lake. South winds accelerate to around 10-20 kt into Friday, with a few gusts towards 25 kt into Saturday. Additional chances for showers and thunderstorms Saturday night through early next week, with south to southwest winds expected to continue. Sheppard && .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