Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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639 FXUS63 KFSD 260814 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 314 AM CDT Sun May 26 2024 .KEY MESSAGES... - Scattered to isolated showers and thunderstorms are expected today with better coverage late afternoon and evening near and west of the James River. Main threats small hail and wind gusts to 50 mph. - Scattered showers and thunderstorms possible near and east of an Ivanhoe to Cherokee line Monday late morning into the afternoon. Small hail and wind gusts to 50 mph will be the main threats. - Next chance for thunderstorms will come Wednesday night with some threat for severe weather in central SD on Thursday afternoon and night. && .DISCUSSION... Issued at 313 AM CDT Sun May 26 2024 The weak support for showers and thunderstorms will exit the area early this morning with just a lingering chance across parts of northwest IA. Some weak LLJ forcing into northwest IA and residual weak instability are the main drivers. A few sprinkles will be possible over mainly southwest MN within a region of mid level moisture and weak forcing/instability through about sunrise. Overall most of today will be dry with only very spotty chances for showers and thunderstorms. Model soundings indicate some weakness in the cap this afternoon with daytime heating, but instability is weak so right now not expecting anything other than isolated lightning and brief heavy downpours. A push of lift and weak elevated moisture and instability move into central and northern SD this evening and overnight but once again severe weather is unlikely and precipitation amounts will be on the light side. Some minor potential for small hail and wind gusts to 50 mph west of the James River late this afternoon and evening. This wave is expected to move through the area on Monday with scattered diurnally driven showers and thunderstorms expected Monday afternoon and evening. While the overall environment is not very supportive of severe weather a fairly low freezing level (about 7000 ft AGL) and unidirectional northwest flow with decent speed shear may support hail to dime size and wind gust of 50 to 60 mph. The better chance will be east of a line from roughly Ivanhoe to Cherokee. Otherwise temperatures both today and Memorial Day will be near normal with windy conditions expected on Memorial Day. Tuesday should see northwest flow aloft continue, but the diurnally driven instability looks much weaker, so even afternoon showers and isolated thunderstorms look unlikely. Upper level ridging builds in Tuesday afternoon into Wednesday which supports additional drier conditions. Temperatures will be seasonally mild with highs in the 70s and lows from the mid 40s to lower 50s. Wednesday night into Saturday will see a series of waves move through the flow over the Northern Plains, bringing chance for showers and storms. Right now the better instability appears to be just west of the area on Thursday so Thursday night might be the better chance for some severe weather. While instability is not as high there is some moderate agreement that a wave will move onto the Northern Plains Saturday. Seasonal temperatures are expected with highs mainly in the 70s and lows in the 50s. Maybe a few 80s in central SD on Thursday. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1057 PM CDT Sat May 25 2024 Showers and embedded thunderstorms west of U.S. Highway 81 at the start of this period are expected to diminish in coverage through 10Z as thunderstorms over Nebraska expand eastward toward U.S. Highway 20 corridor and northwest Iowa. Convective activity exits east of the area by daybreak Sunday, replaced by areas of MVFR-locally IFR ceilings/visibility along with a chance of light showers lingering over portions of northwest Iowa into the morning hours. Improvement to more widespread VFR conditions expected again after 18Z, however additional showers/storms may move into the James River Valley late in this period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...08 AVIATION...JH