224 FXUS63 KMPX 251859 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 159 PM CDT Fri Jul 25 2025 .KEY MESSAGES... - Quiet weather through Saturday aside from poor air quality through this evening due to wildfire smoke. - Hot and humid this weekend with highs in the upper 80s to mid 90s and heat indices in the upper 90s to mid 100s on Sunday. - Unsettled weather resumes late Sunday and lasts through early next week with thunderstorm chances. Severe storms are possible Sunday night. && .DISCUSSION... Issued at 159 PM CDT Fri Jul 25 2025 Haze has lifted out of southern MN as southeasterly winds push this round of wildfire smoke north. Improvement can be expected across central MN and WI later today and this evening. The thicker haze/smoke has stunted some CU growth thus far across east central MN and WI, but as it thins we may see better development later this afternoon. Temperatures are on track to reach the mid 80s. Quiet weather is expected tonight. Dew points will remain in the mid to upper 60s so lows won`t drop much below 70. Can`t rule out some patchy fog again late, but a bit more cloud cover should prevent it from becoming as widespread as this morning. Richer moisture begins to arrive Saturday across western MN, but an MCV across the central Plains today is expected to track east northeast across the mid Mississippi Valley tonight. That will tend to redirect the deepest moisture with it to the east and could leave a depressed area of temps aloft in its wake. Southeast flow from that area may keep temperatures across parts of southeastern MN and western WI from reaching the upper 80s. Therefore, while it will still be warm and humid, heat headlines likely aren`t going to be necessary in those areas. The exception will be far western MN where thermal ridging will be advancing in and coinciding with dew points in the mid 70s. Heat indices there should reach around 100. The thermal ridging will build farther east for Sunday. Temperatures shouldn`t be the main story, although the typical hot areas of west central MN could make a run for the upper 90s if 925 mb temps of +30C pan out. Rather, dew points of 75 to 80 will be the main driver of dangerous heat indices and WBGTs. Steep mid level lapse rates and 700 mb temps exceeding +12C should keep the area capped, so the chance of convective contamination of the airmass is low. Heat indices are expected to reach around 105 across southwestern MN where dew points will be in the upper 70s. The heat indices could be higher if the air temps exceed the forecasted mid 90s or dew points eclipse 80. WBGTs in the upper 80s are also possible. An Extreme Heat Watch or warning will be needed soon, extending northeast into the Twin Cities metro where criteria is 100. The ridge will build westward Sunday night while a trough reaches central Canada. This will turn mid level winds more westerly and speeds will increase to around 40 kts. Potentially extreme instability will develop Sunday afternoon, lingering well into Sunday night. Mesoscale features rippling on the northern periphery of the ridge should be able to get one or more MCSs developing Sunday afternoon over the northern Plains or Upper Midwest. There remains low confidence where and when these individual complex(es) develop and how far south they will impact. 700 mb temperatures should be warm and marginally tolerant of convection. There are a lot of unknowns at this range. Right now the best chances for impacts are across central and northern MN. What becomes of Sunday night will set the stage for Monday. A boundary will lay out somewhere in the area. Seasonably high pwats, an extremely unstable airmass, and a strengthening N-S LLJ later in the day impinging on the E-W boundary could bring renewed thunderstorm development capable of very heavy rain. The front should sag a little farther south for Tuesday which should shunt most of the thunderstorm threat to IA, but spatial differences in the frontal position warrant continuing low PoPs. Cooler and drier air will follow for the rest of the week with surface high pressure building in. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1154 AM CDT Fri Jul 25 2025 For WI terminals, MVFR visibilities look to continue through this afternoon due to wildfire smoke. Conditions should improve to VFR this evening, but at least patchy fog looks possible again near sunrise Saturday morning. Have gone with 3sm visibilities for both RNH and EAU near sunrise before burning off and returning to VFR by mid-morning. Southern MN terminals (RWF and MKT) have a decent chance of seeing MVFR cigs Saturday morning as increasing moisture saturates the thermal profile. Conditions should improve to VFR by late morning. Elsewhere, VFR is expected the entire period. South-southeasterly winds will slow a few mph tonight and turn south-southwesterly Saturday morning. KMSP...No additional concerns. /OUTLOOK FOR KMSP/ SUN...Chc morning MVFR cigs. Chc P.M. -TSRA. Wind S 5-10kts. MON...VFR. Chc MVFR A.M. -TSRA. Wind N 5-10 kts. TUE...VFR. Chc MVFR A.M. -TSRA. Wind N 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Heat Advisory from noon to 8 PM CDT Saturday for Chippewa-Lac Qui Parle-Stevens-Swift-Yellow Medicine. WI...None. && $$ DISCUSSION...Borghoff AVIATION...CTG