296 FXUS63 KUNR 230751 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 151 AM MDT Mon Jun 23 2025 .KEY MESSAGES... - Nice today, but TSRA return tonight - Slight risk (2 out of 5) of severe thunderstorms Tuesday afternoon/evening - Unsettled for the rest of the week with trends pointing toward warmer/hotter weather for Thursday through Saturday && .DISCUSSION...(Today Through Sunday) Issued at 149 AM MDT Mon Jun 23 2025 07z surface analysis had cool front well southeast of the CWA with modest high building from the Rockies into the northern Plains. Water vapour loop had upper trough from southwest Canada into southwest CONUS. Tail end of shortwave over the eastern Dakotas with decreasing shra/TS over south-central SD per regional radar loop. Main forecast concern this week revolves around severe potential. Today, subsidence/drying in wake of shortwave leading to a nice day with near seasonal temperatures, which will be close to guidance. Tonight, southwest CONUS shortwave moves into the Rockies with weak low developing over CO, promoting weak low level jet/theta-e advection into the region. Elevated TSRA will occur. Lows tonight will be near guidance. Tuesday, shortwave moves into WY allowing surface low to slowly deepen and a warm front to develop ahead of it extending from north-central WY into the NE panhandle by afternoon. Southeasterly low level flow will be topped by southwesterly mid- level flow lengthening hodographs with 40-50+kts 0-6km bulk shear. 1-2KJ/kg SBCAPE forecast by afternoon. When cap breaks (it should given warm front/shortwave approaching), supercells are a good bet over northeastern WY, which will support large (possible very large) hail and damaging wind gusts as they move east around 20kts (right mover) or northeast around 25kts (left mover). Forecast hodographs suggest splitting storms may occur. 0-1km shear not sounding the tornado klaxon, but with northeastern WY positioned near the warm front and northeast of the surface low, conditions may become favorable for isolated tornadoes. How far east the severe storms make it in question given less favorable environment further east in western SD. Temperatures will be near guidance. Wednesday, another shortwave will move through with additional TSRA chances. Wouldn`t be surprised to see active storms given pattern with CSU MLP and SPC painting potential for severe hail/wind. Thursday through Saturday, ensemble guidance trends have been trending hotter, especially Friday, but confidence in details not particularly high given 5-10F temperatures spreads in NBM guidance. Generally drier weather foreseen, but a stronger system/cold front may drop late Saturday with higher PoPs. && .AVIATION...(For the 06Z TAFS Through 06Z Monday Night) Issued At 1002 PM MDT Sun Jun 22 2025 Scattered showers and storms over parts of the western SD plains tonight will taper off from west to east in the overnight hours. Localized MVFR to IFR conditions will be possible in storms. Otherwise expect VFR conditions through the TAF period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Helgeson AVIATION...Dye