Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
023 FXUS63 KMKX 270224 AAA AFDMKX Area Forecast Discussion...UPDATED National Weather Service Milwaukee/Sullivan WI 924 PM CDT Sat Jul 26 2025 .KEY MESSAGES... - Fog is expected to develop overnight, with areas of dense fog (visibility less than a quarter mile) possible. - Middle to upper 90s heat index values are expected Sunday, with values over 100 degrees possible for Monday. - The next thunderstorm chances (20-30%) are overnight Sunday night into Monday morning, mainly west of Interstate 39 corridor. A stronger storm or two is possible. - There are additional periodic shower and storm chances for Tuesday into Wednesday. - Milder, near normal temperatures and less humid conditions look likely for the second half of the week. && .UPDATE... Issued 924 PM CDT Sat Jul 26 2025 Any lingering middle level clouds over southeast Wisconsin should move east of the area overnight. Clear skies, light winds and lingering low level moisture/high dew points from rainfall earlier today should help fog develop overnight into Sunday morning. Areas of dense fog are possible, especially for southern and western portions of the forecast area. Low stratus clouds may accompany the fog. Will see how the fog trends overnight before any Dense Fog Advisory headlines are issued. Any fog and low stratus clouds should dissipate by middle morning on Sunday. Wood && .SHORT TERM... Issued 315 PM CDT Sat Jul 26 2025 Tonight through Monday night: Warm frontal boundary continues to lift northward this afternoon with some lingering light showers. Expecting drier conditions this evening as the shortwave trough and main forcing shifts east. However latest satellite/radar imagery shows an MCV across south- central IA that looks to move eastward through the evening. While expecting a dry forecast and not much development along this feature given lack of upper- level support, will still keep an eye on it just in case. Otherwise main concern tonight will be the fog potential. Given the tropical airmass, high dewpoints in the lower 70s, recent rainfall, and light winds will be favorable for widespread fog development across southern WI. Will also likely see areas of dense fog develop as well and may need a dense fog advisory later this evening/tonight. While the better potential for dense fog looks to be for areas along and south of I-94, difficult to pinpoint how widespread and north it may spread tonight. Fog will persist into Sunday morning. Thus, will hold off on issuing the advisory at this time and wait to see how it develops to get a better sense of its coverage. Sunday will be the start of the hot and humid stretch with temps climbing into the upper 80s and lower 90s with low to mid 70s dewpoint. Thus heat indices will be in the mid to upper 90s and briefly touch 100F in some locations Sunday afternoon. While approaching 100F in some spots, will hold off on a Heat Advisory as some uncertainty with the temps/heat indices exist given the lingering fog/cloud potential in the morning as well as incoming wildfire smoke aloft moving in through the afternoon. Thus these may impact temps from reaching as hot as they could. The heat and humidity will continue for Monday as the upper- level sub-tropical high gradually meanders westward over the southeast CONUS. The hottest temps and warmest dewpoints look to occur on Monday with high in the low to mid 90s and dewpoints in the mid to upper 70s. Thus likely to exceed 100F and even 105F heat indices. While potential and probability support heat headline criteria being met Monday, the one wrinkle is the potential MCS working its way across the region overnight Sunday into Monday morning as suggest by the end of the CAMs runs (HRRR and NAM Nest). So may see a similar scenario as we saw this past Wednesday where lingering showers/storm activity and cloud cover into Monday morning delayed the onset of the higher heat indices. However, once things clear it would not take much for heat indices to climb into the triple digits for the afternoon. So will monitor trends given this uncertainty to get a better handle before issuing any heat headlines. Lastly cannot rule out with this potential MCS Sunday night into Monday to bring strong to severe storm or two to southern WI. Given the tropical airmass, elevated dewpoints, 18z HRRR MUCAPE exceeding 3000 J/kg overnight along with +30 knots of shear would support the development of some stronger convection. Thus agree with SPC Day 2 Outlook highlighting the 1 out of 5 risk and will need to monitor how the models trend and handle this MCS. Wagner && .LONG TERM... Issued 315 PM CDT Sat Jul 26 2025 Tuesday through Saturday: Upper-level ridge persists into Tuesday and may see heat and humidity linger as well. However, mid-range models continue to hint at an upper-level shortwave trough over-running the ridge into Tuesday which may bring another bout of rain and storms to the area. Thus leaving the heat potential in question. Continue to the see the upper-level high gradually meanders back westward through the middle of the week allowing the upper-level trough across central Canada to work its way across the Upper Midwest. This will establish northwesterly flow over the Upper- Mississippi River Valley and ultimately a drier and milder pattern with near normal temps through the second half of the week as surface high pressure builds over the region into next weekend. Wagner && .AVIATION... Issued 924 PM CDT Sat Jul 26 2025 Any lingering middle level clouds over southeast Wisconsin should move east of the area overnight. Clear skies, light winds and lingering low level moisture from rainfall earlier today should help fog with 1 to 4 mile visibility values develop overnight into Sunday morning. Areas of dense fog of one quarter mile or less are possible, especially for southern and western portions of the forecast area. Low stratus clouds may accompany the fog, with ceilings below 1000 feet AGL. Any fog and low stratus clouds should dissipate by middle morning on Sunday. Light south winds are expected on Sunday, with southeast winds by Sunday afternoon for terminals near Lake Michigan. Light south winds should linger Sunday night. Scattered diurnal cumulus clouds around 3500 to 4000 feet AGL are expected Sunday afternoon. Wood && .MARINE... Issued 924 PM CDT Sat Jul 26 2025 Some fog is expected to develop overnight into Monday morning, with patchy dense fog possible. Light to occasionally moderate south to southwest winds will prevail into Monday. There will be additional round of showers and thunderstorms to track across the region Sunday night into Monday and again by the middle of the week. There may be more variable winds accompanying any storm complex that traverses the lake through early next week. A cold front looks to push across the lake by Wednesday, bringing increased north to northeast winds. High pressure around 30.3 inches should then move into the region for the end of the week. && .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