704 FXUS63 KMPX 161944 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 244 PM CDT Wed Apr 16 2025 .KEY MESSAGES... - Elevated fire weather conditions this afternoon due to low relative humidity and breezy winds. The two areas of most concern are southwestern MN and east-central MN to northern WI. - Strong to severe thunderstorms are possible beginning Thursday afternoon through early Friday. Large hail is the primary threat. - An active pattern persists through the middle of next week, with a larger system possible Sunday into Monday. && .DISCUSSION... Issued at 244 PM CDT Wed Apr 16 2025 The immediate concern this afternoon remains elevated to near- critical fire weather conditions for portions of southwestern Minnesota as well as east-central Minnesota to northern Wisconsin. Surface observations show temperatures in the low to mid 60s with winds out of the southeast at 15-20 gusting to 30mph in southwestern Minnesota and weaker winds with temperatures in the 50s elsewhere. The window for near-critical fire weather conditions has remained quite small with the peak over the next 3 hours before conditions begin to improve as we slowly lose daylight, resulting in weaker mixing and therefore slower winds and cooling temperatures. GOES 19 satellite imagery shows a band of thicker clouds along and north of I-94 moving eastwards with thinner clouds along the Minnesota River which will further point towards southwestern Minnesota being at greatest risk for fire weather conditions. Skies will remain partly cloudy tonight as our next chance for showers and thunderstorms arrives on Thursday as a surge of low to mid level warm air advection will produce spotty showers as early as mid morning, ahead of the primary forcing which will arrive as a low level jet strengthens later in the evening coinciding with the arrival of a mid level shortwave. Longer range CAM guidance that has resolved the entire event shows a swath of early convection moving from southwest Minnesota towards the Twin Cities metro and into northern Wisconsin ahead of a secondary round that looks to be stronger during the evening and overnight. Going through the suite of forecast soundings from both the global and CAM guidance, our CAPE profile is deep but not wide such that our peak updraft intensity will end up on the lower end of the spectrum despite 1500-2000 J/KG such that we will have an upper limit to just how strong storms will end up. Other key factors include weak to mediocre shear at best, strongest during the evening as the low level jet and mid level shortwave combine to produce a triple-point feature over southern Minnesota and northern Iowa. Lapse rates look to remain on the high end such that large hail will remain the primary risk with severe thunderstorms, with strong winds being a secondary weaker threat. LCLs should range from 3-4kft such that tornadoes are not favored at this time, especially given the poor low level shear compared to the better environment in the mid levels. All things put together, our best chance for severe weather will likely be elevated hail producing storms during the evening favoring southern Minnesota and northern Iowa progressing eastwards as the low level jet migrates towards lower Lake Michigan overnight into early Friday. There should be enough forcing north of the better environment to produce scattered to widespread showers such that most of the region will see at least some amount of rain from the event with lower amounts in west-central Minnesota. WPC QPF shows a peak QPF from the convective bands in the 1.5-2 inch range compared to 3-4 inches in the HREF LPMM QPF, however the HREF solution is likely too hot and would rely on multiple rounds of convection moving over the same area. As we move beyond and into the weekend, showers will end early on Friday with mostly cloudy skies lingering throughout the day as we do not see enough subsidence to erode the cloud cover until Saturday. Quick moving high pressure will result in mostly clear skies and cooler temperatures on Saturday before clouds return gradually Sunday ahead of our next system. The suite of global guidance all show a system moving through the region late Sunday into Monday with a large degree of variance in solutions among ensemble members. The deterministic GEM/ECMWF both show a well developed surface low and upper level trough swinging across the region from south-western Iowa to southeast Minnesota, which would place our area on the northwest cooler side and result in widespread rain showers but little to no chance for severe weather. The 12z GFS shows a much farther east trajectory and weaker surface based system such that we would end up almost completely dry for the same time period. GEFS/EPS/CFS guidance all show varying degrees within the ensembles, with generally 50-60% of membership showing meaningful precipitation falling at MSP and the rest favoring a drier solution. The most likely area to see precipitation will be southeastern Minnesota and western Wisconsin with lower chances to the northwest farther away from the system. One question is also if we manage to squeeze flurries or light snow out of the far northwestern edge as some members do have a few tenths of accumulation in the Alexandria area, however this is a low probability solution as less than 5% of members show anything but rain within the greater ensembles. Suffice to say, the Sunday to Monday system is by no means a high confidence forecast and will be something to monitor closely as we head towards the weekend, with the hope being ensemble guidance comes into better agreement with more membership showing either a dry or wet solution. The active pattern continues into the middle of next week as persistent 20 to 40 percent chance for showers persists through the end of the period with zonal flow aloft and potential for weak shortwaves as well as no strong surface systems. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1245 PM CDT Wed Apr 16 2025 Not much happening this period until Thursday morning. One trend we`ve seen with the 12z models is a lack of activity within the warm advection Thursday morning, with most models holding off on storms until the afternoon along the cold front. The one exception is up in central MN, where several CAMs show activity developing during the late morning hours. Otherwise, fairly widespread convection is expected Thursday afternoon across central and eastern MN ahead of the cold front that will be moving across western MN during peak heating on Thursday. Given the timing, only the end of the 30 hour TAF period at MSP has a TS threat worthy of mentioning this period. For CIGS, went the route of the RAP, which shows low cigs likely holding off until after the fropa, so no widespread warm sector IFR/MVFR cigs like we`re seeing with the LAV, with all TAFs remaining VFR this period, though this is something we`ll continue to reassess through the night. KMSP...HREF shows TS probabilities of over 80% at MSP Thursday afternoon, so jumped out beyond a prob30 for that threat with the prevailing shra & tempo TS Thursday afternoon. It`s thunder, so there`s still plenty of time for the placement of TS to change, though the 12z HREF would say it could be a very active afternoon on Thursday, with upwards of 2" of rain possible. /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...TDH AVIATION...MPG