


Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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369 FXUS63 KFSD 150345 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 1045 PM CDT Mon Jul 14 2025 .KEY MESSAGES... - Hot, humid weather continues through Tuesday with highs in the upper 80s to upper 90s. A cooldown comes for Wednesday through Friday with highs only in the 70s to lower 80s. - Scattered thunderstorms are expected to develop in central South Dakota and Nebraska Tuesday afternoon, tracking east Tuesday evening. A few strong to severe thunderstorms may develop with this activity, bringing heavy downpours, hail up to golf ball size, wind gusts up to 70 mph, and perhaps a tornado or two. The greatest threat comes 5 PM to 9 PM. - Periodic (<50%) rain chances continue through Wednesday night and again through the upcoming weekend and early next week. && .DISCUSSION... Issued at 229 PM CDT Mon Jul 14 2025 TONIGHT: Hot, humid weather continues overnight amidst a warm air advection and a light south wind. A weak ridge-riding shortwave will triggered scattered storms in western SD this evening, tracking into northeast SD overnight. Given very weak deep layer shear, upper ridge influence, and a very dry subcloud layer, seems unlikely to see any impacts from this activity aside from a very low chance of virga or sprinkles. Temperatures will only fall into the 60s to near 70 degrees overnight. TUESDAY: Tuesday brings another hot, humid day with dew points rebounding to the mid 60s to mid 70s. Models have high confidence in scattered Tstorms developing near a cold front draped from the NE Panhandle to south central SD to west central MN late Tuesday afternoon. A moderately unstable airmass with 7-8 C/km mid level lapse rates and a stronger approaching mid level wave in zonal flow should be sufficient to produce scattered strong to severe Tstorms. Initially expect cells to develop in/near south central SD, but 20- 35 kts of 0-6km deep layer shear mostly parallel to the front suggests storms favors multicells growing upscale into a linear complex. Big questions are 1) how far east storms initially develop (Huron-Gregory vs Pierre-Kadoka), 2) coverage (isolated vs scattered) and severity (or lack thereof) for additional storms developing east of the James River Valley overnight (seems likely but perhaps not severe), and 3) whether the resultant MCS will track southeast near the MO River corridor (less likely) or dive further south directly into central NE (more likely). Pwat values of 1.5- 1.75" favor heavy downpours with any storms. HREF LPMM suggest pockets of 1.5-2.5 inches of rain are possible, especially in south central SD, but discrepancies in the ensemble data lend to low confidence in rainfall amounts near and southeast of a Tracy to Sioux Falls to Yankton line. Regardless, the main threats still appear to be locally heavy downpours, wind gusts up to 70 mph, large hail up to half dollar size, and to a lesser extent perhaps a brief tornado. HREF UH tracks and less favorable environmental conditions further east suggest severe weather threat should gradually wane through the overnight hours. WEDNESDAY AND THURSDAY: Closer proximity of a northern stream longwave trough and persistent stratus brings a notable cooldown for Wednesday, with highs 10-15 degrees cooler than Tuesday (mid 60s to lower 80s). We may also see lingering showers and/or drizzle with abundant cloud cover dictating how much insolation-related heating we can achieve. Coupled with a breezy north wind, this looks to be a fairly dreary day for any outdoor activities. Should get drier mid to upper level air in Thursday behind the upper trough, making for a cool day with more sunshine. FRIDAY THROUGH EARLY NEXT WEEK: A more active, zonal flow pattern aloft brings periodic rain chances through next weekend and early next week as Southeast ridging regresses westward and ridge-riding shortwaves slide through the North Central part of the CONUS. As highlighted in the CPC 6 to 10 day outlook, there`s some signal for a wetter pattern with multiple rounds of convection early next week with 90th percentile (NAEFS-relative) precipitable water content coupled with a stronger, northern stream longwave trough digging in. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1045 PM CDT Mon Jul 14 2025 VFR conditions begin the TAF period. Showers and a few thunderstorms persist just west of the forecast area late this evening. They could drift near KHON so have added a PROD30 group for the first few hours of the period. Otherwise light southerly winds will persist through the night along with some low level wind shear (LLWS) thanks to the strengthening low level jet (LLJ). A cold front will push into the area tomorrow afternoon, sparking new thunderstorm development along the boundary. Showers and storms will push southeastwards through the reset of the afternoon and evening hours, brining chances for rain to all TAF sites. At the same time, ceilings will be lowering to MVFR/IFR levels behind the front. The lowered ceilings and showers/storms will finish out the TAF period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...BP AVIATION...Meyers