Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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679 FXUS63 KUNR 251735 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1135 AM MDT Thu Apr 25 2024 .KEY MESSAGES... - Thunderstorms expected this afternoon and evening. Heavy rain, small hail, and gusty winds possible. - More widespread precipitation expected Friday through much of the weekend. - Warmer and dry conditions move in early next week. && .DISCUSSION...(Today Through Wednesday) Issued at 218 AM MDT Thu Apr 25 2024 Current Water Vapor and upper air models show mild upper ridge over the northern and central plains this morning, while weak upper low sits over the southwest CONUS. At the surface, high pressure sits over eastern NE, with a surface low over north central CO. Temperatures this morning sit in the mid 40s to mid 50s, with light winds. Return flow and WAA will raise dew points this afternoon into the upper 40s and low 50s over much of western SD. With daytime heating and added moisture, expect storms/showers to develop late this morning into the afternoon. Severe parameters aren`t co- located well, with the better CAPE today being over far western SD, and the best 0-6km shear over south central and central SD. Black Hills and southwestern SD sit in marginal risk for today, where the better instability (1000-1500 j/Kg) and weaker capping is expected. As storms travel east into the better shear environment, larger hail may be possible. Later Thursday night into Friday morning, upper wave swings through CO and into NE. Wrap-around precipitation will fill in over much of the forecast area. Then later Saturday into Sunday, a secondary wave swings up from the four corners into the plains. While precipitation diminishes early Saturday from the first system, expect redevelopment over much of the region. A more northerly track coupled with less moisture will keep the higher QPFs over this round east of the CWA. NAEFS probabilities keep us in the 99.5% Friday morning through the first half of Saturday, dropping to the 90th percentile through Sunday. Widespread 1-2" QPF will be possible through the weekend. Following passage of this system, 2-3mb/3hr press rises will make for a breezy Sunday. Expect temperatures to also cool off for the weekend with these systems passing through, with highs mainly in the 40s and 50s. Moving into next week, upper flow becomes quasi-zonal, with drier conditions expected. By mid-week, upper ridge builds back into the northern/central plains, with temperatures gradually warming back into the 70s by Tues/Weds. Long-range models hint at upper trough swinging across southern Canada into the northern plains towards next weekend, and we may see a return to unsettled weather. && .AVIATION...(For the 18Z TAFS Through 18Z Friday) Issued At 1115 AM MDT Thu Apr 25 2024 VFR conditions are expected through early afternoon. Showers and thunderstorms will increase in coverage and intensity after 20Z. MVFR/IFR conditions are expected with the heavier precipitation. Widespread MVFR/local IFR conditions expected tonight with expanding area of stratus and showers. Northerly winds will increase to 15-25 kts with gusts around 35 kts Friday morning. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Dye AVIATION...Pojorlie