983 FXUS63 KMPX 270551 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1251 AM CDT Sun Jul 27 2025 .KEY MESSAGES... - Heat and humidity intensify Sunday with highs in the upper 80s to mid 90s and heat indices in the upper 90s to mid 100s. - Unsettled weather resumes late Sunday and lasts through early next week. Severe storms are possible Sunday night and heavy rainfall is possible Monday night. - Cooler and drier conditions later next week. && .DISCUSSION... Issued at 258 PM CDT Sat Jul 26 2025 A few early day storms across western MN have finally dissipated and the growth of CU from patchy overnight fog is also decaying this afternoon. Temperatures have climbed into the mid and upper 80s, with a few spots in western MN now touching 90. Dew points have been mostly in the low 70s. Thunderstorm development could occur this evening along the ND/SD border area and spread east northeast overnight. Much of this activity should remain north of the area, but cannot rule out a few storms as far south as central MN through early Sunday. 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 in the mid to upper 70s will be the main driver of dangerous heat indices and WBGTs. Steep mid level lapse rates and 700 mb temps exceeding +12C by afternoon should keep the area capped, so the chance of convective contamination of the airmass is low. Heat indices are expected to reach around 110 across southwestern MN where dew points will be in the upper 70s and temperatures in the mid to upper 90s. Heat indices decrease to around 100 across central MN and western WI. WBGTs in the upper 80s are also possible. The Extreme Heat Watch has been upgraded to a warning or a Heat Advisory depending on the resultant heat indices. 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. Extreme instability will develop Sunday afternoon, lingering well into Sunday night. Residual boundaries from the morning convection should get thunderstorm initiation in the afternoon over northwest MN, which should be able to develop a cold pool and dive southeast Sunday night. Models are beginning to handle this scenario a bit better, and the SPC has upgraded to a Slight risk across central MN and northern WI. Damaging winds will be the main threat, but some large hail given the very steep lapse rates and a couple QLCS tornadoes are also possible. What becomes of Sunday night will set the stage for later Monday. A boundary will lay out somewhere across the area, likely beginning the day in southern MN then lifting north during the afternoon. Very high pwats possibly greater than 2 inches, an extremely unstable airmass remaining in place, 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. Some guidance suggest the possibility of an MCS developing and tracking east along the front, which would lead to a damaging wind threat. Another possibility is for training thunderstorms along the front, or along the southern edge of the cold pool from the MCS. Confidence and predictability for where this will set up are still low and will depend on a number of things between now and then. Solutions range from the heaviest rain falling as far north as central MN and northern WI, to as far south as southeastern SD and IA. Confidence in the occurrence of heavy rain is much higher and some solutions highlight areas receiving greater than 3 or 4 inches. 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 Tuesday night and Wednesday. Cooler and drier air will follow for the rest of the week with surface high pressure building in. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1251 AM CDT Sun Jul 27 2025 VFR with some MVFR/IFR fog possible this morning and have added TEMPO groups where fog looked most likely to develop. Mostly clear skies will transition to elevated surface smoke AOA 20kft this afternoon. Likely TSRA is expected to sweep across most sites from west to east during the pre-dawn hours of Monday morning. Have adjusted PROB30 timing accordingly to reflect trends in latest CAMs. Light southerly winds will increase to between 10-12kts with gusts ranging between 18-20kts across western sites this afternoon. KMSP...Fog possible this morning but likely should remain in the river valley and not reach the terminals. Light southerly winds will increase to near 10kts with a few gusts near 18kts through this afternoon. Still keeping an eye on pre-dawn storms for early Monday morning. Have pushed back timing a couple of hours in the PROB30 grouping to reflect current trends with the latest CAMs. Winds will begin to veer to the west after 10z and eventually NW next TAF period. /OUTLOOK FOR KMSP/ TUE...VFR. Chc MVFR A.M. -TSRA. Wind NE 5-10 kts. WED...VFR. Chc MVFR A.M. -TSRA. Wind NE 5-10G15 kts. THU...VFR. Wind E 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Heat Advisory from noon today to 9 PM CDT this evening for Benton-Douglas-Freeborn-Goodhue-Kanabec-Mille Lacs- Morrison-Stearns-Steele-Todd. Extreme Heat Warning from noon today to 9 PM CDT this evening for Anoka-Blue Earth-Brown-Carver-Chippewa-Chisago-Dakota- Faribault-Hennepin-Isanti-Kandiyohi-Lac Qui Parle-Le Sueur-Martin-McLeod-Meeker-Nicollet-Pope-Ramsey-Redwood- Renville-Rice-Scott-Sherburne-Sibley-Stevens-Swift-Waseca- Washington-Watonwan-Wright-Yellow Medicine. WI...Heat Advisory from noon today to 9 PM CDT this evening for Barron-Chippewa-Dunn-Eau Claire-Pepin-Pierce-Polk-Rusk- St. Croix. && $$ DISCUSSION...Borghoff AVIATION...Dunleavy