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Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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077 FXUS63 KUNR 152005 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 205 PM MDT Mon Jul 15 2024 .KEY MESSAGES... -Near average temperatures, with chances for storms most days -A few stronger to severe storms possible this afternoon and evening && .DISCUSSION...(This Evening Through Monday) Issued at 133 PM MDT Mon Jul 15 2024 Latest analysis shows an upper ridge over the western CONUS and Canadian Rockies. An upper low is located over Hudson Bay with a trough swinging southward across Manitoba/Saskatchewan, leading 50-70kt 300mb westerly flow across the region this afternoon. A surface high is dropping southward from the Canadian prairie provinces into eastern MT and ND this afternoon with a surface trough to the east of the Rockies. Surface dewpoints are mainly in the 50s, with some 30-40F readings over northeastern Wyoming and in the upper 60s over parts of south central SD. SBCAPE has risen to 500 (NE WY) to 2000 (south central SD) J/kg this afternoon. A band of 1000+ J/kg extends along the eastern slopes of the Black Hills into southwestern SD which coincides with a region of 40+kts 0-6km Bulk Shear. Lift associated with a 70+kt jet streak crossing the area is expected to trigger thunderstorm development over northeastern Wyoming and the Black Hills into southwestern South Dakota during the late aftn/early evening. Shear profiles indicate that a few strong to severe storms are possible. That convection will spread eastward tonight into south-central SD. Another band of storms may dive southeastward out of North Dakota into parts of northwestern and north central SD later tonight. Additional storms are possible on Tuesday afternoon/evening with a stronger short wave trough crossing the region and steep lapse rates in place with northwesterly flow aloft. Tuesday highs will be similar, or a few degrees cooler, than today. Slightly drier conditions are expected Wednesday with more subsidence behind the Tuesday short wave, with a better focus around and south of the Black Hills. Next strong short wave trough looks to move through Thursday night/early Friday, with temperatures rebounding a few degrees late week as upper ridge amplifies over the Northern Rockies. Better focus for storms may shift a bit east over the weekend as upper ridge attempts to build over the Northern Plains. && .AVIATION...(For the 18Z TAFS Through 18Z Tuesday) Issued At 1119 AM MDT Mon Jul 15 2024 VFR conditions are expected through the forecast period. Scattered showers and thunderstorms are expected this afternoon into tonight, especially from northeast WY to southwest SD. Transient MVFR/IFR conditions are possible near any stronger storms. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...10 AVIATION...SE