655 FXUS63 KMPX 170839 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 339 AM CDT Thu Apr 17 2025 .KEY MESSAGES... - Today, strong to severe thunderstorms possible this afternoon through this evening. Large hail is the primary threat. Localized heavy rain, damaging wind, or an isolated tornado can`t be ruled out. - Additional rain chances Sunday into early Monday, and again Tuesday of next week, but no significant weather impacts are expected. && .DISCUSSION... Issued at 244 PM CDT Wed Apr 16 2025 TODAY...Thunderstorms are expected to develop this afternoon and last into the evening. A few storms could be strong to severe, especially in southern Minnesota. The main threat is large hail, but heavy rain, damaging winds, and an isolated tornado can`t be ruled out. It was a dry and breezy morning, with dewpoints in the upper 20s to lower 30s,and winds out of the southeast at around 10 to 15 mph. That will change later today as a strong low level jet will develop and advect moisture northward across the region. Meanwhile southwest flow aloft has already brought an elevated mixed layer across the region, with 500-700mb lapse rates around 7.5 to 8.5 C/km already in place across as shown via the SPC Mesoanalysis page. The addition of low level moisture, together with afternoon heating will lead to around 1000 to 2000 J/kg of MLCAPE within in inverted surface pressure trough extending up from Iowa into central Minnesota. Storms are expected to develop this afternoon, and move eastward this evening. Hodographs still show an elongated wind profile, but there is veering in the lowest 3 km, and one could argue that forecast soundings are more supportive of surface- based storms than they were yesterday. For that reason, large hail is still the primary threat, but damaging and an isolated tornado can`t be ruled out. In addition to the severe threat, PWAT values will approach 1.1 to 1.3 inches, which is near record territory for mid-April. Although the storms will be moving east, any storms that train over the same area could dump 2 to 3 inches or more of rain over an isolated area, which is supported by some of the individual HiRes solutions. Since we have been fairly dry, the risk for excessive runoff is low, so the flood risk would primarily be for urban areas. FRIDAY THROUGH WEDNESDAY...Lingering rain showers will last into Friday before the system departs. Cooler and drier air will follow into Saturday, with highs only in the low to mid 50s. On Sunday, a shortwave trough over the Texas panhandle is forecast to move up toward the Great Lakes. Widespread rain is expected with this system. A westerly track would bring this rain across Minnesota and Wisconsin, while an easterly track would only bring rain to Wisconsin. Ensemble guidance off the ENS is farther west, and the GEFS is farther east. The blended guidance with highest rainfall chances east of I-35, and lesser amounts to the west, seem appropriate. Forecast confidence in this system should increase over the next couple of days. Lastly, there is another shortwave expected to move through Tuesday into Tuesday night. This will bring additional rain chances, but it will be moving through quickly. There is a small chance that we could build enough instability for storms, but at this point it looks like rather low impact weather for next week. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1038 PM CDT Wed Apr 16 2025 All TAF sites to start out with VFR conditions and breezy SE winds. Winds will remain elevated through the overnight hours, from the SE with sustained speeds 10-15kts with gusts around 20kts. Strong nocturnal jetting ahead of an approaching low pressure system will produce southerly winds 40-45kts at the 2 kft level for much of the overnight hours, which is indicated fairly well in model guidance. Thus, have maintained LLWS mention at all sites. High clouds will prevail from mid-to-late morning then decks in the 020-030 level will move in fairly quickly early afternoon, developing into ceilings mid-to-late afternoon. Ceilings are likely to develop in the late afternoon hours, nearly in coincidence with SHRA/TSRA developing across the Upper Midwest. TSRA is more likely to impact central- southern MN into western WI, thus have left TSRA out of the AXN TAF but have its mention at all other sites. Rain is then expected for all sites during the evening hours with ceilings dropping to MVFR range and potentially IFR range. PROB30 is generally the best that can be put forth for TSRA thru 00z, though TSRA is looking more likely from 00z onward, especially for sites in eastern MN into western WI. KMSP...VFR to start with breezy SE winds with fairly high- confidence LLWS through the morning push. Mid-level ceilings are expected by midday, with rain showers just prior to the afternoon push. TSRA developing in the late afternoon hours may drift near/over MSP, or at least be close enough to impact departure/arrival paths. Higher confidence in TSRA after 00z, hence the prevailing mention there. TSRA window looks to be fairly short, with rainfall and ceilings down to IFR levels from mid-evening onward. Breezy SE winds will continue throughout the day, diminishing Thursday evening. /OUTLOOK FOR KMSP/ FRI...MVFR/-SHRA early, then VFR. Wind NW 10-15 kts. SAT...VFR. Wind NW 10-15 kts. SUN...Chc MVFR/-SHRA. Wind E 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...JRB AVIATION...JPC