Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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103 FXUS63 KUNR 101637 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1037 AM MDT Mon Jun 10 2024 .KEY MESSAGES... - Severe weather is likely today with the primary hazards being locally heavy rainfall, large hail, damaging winds, and an isolated tornado threat. - Near to above average temperatures with near daily chances for showers and storms through the end of the week. && .DISCUSSION...(Today Through Sunday) Issued at 232 AM MDT Mon Jun 10 2024 Current upper air analysis depicts upper level ridge over the region with weak shortwave over WY/MT. Some convection associated with the wave has developed over western ND and portions of NE WY. This wave will move through the CWA this morning with chances for showers and thunderstorms through the early morning hours. The stronger wave responsible for our severe weather threat this afternoon is currently over eastern OR/western ID. This upper level wave will move through the region this afternoon with attendant frontal boundary stretching from CO into WY/SD. Vigorous southerly flow/LLJ will advect ample moisture into the region with sfc dewpoints reaching into the 50s to 60s by early afternoon. Front will reach northeastern WY by noon/early afternoon with ML CAPE in NE WY reaching into the 1000-2000 J/kg range. A few scattered showers/storms may begin developing around this time with 0-6km bulk shear of 30-40kt supportive of rotating updrafts. The front will cross into western SD as the afternoon progresses with thunderstorms increasing in coverage as ML CAPE values across western SD will reach 1500-2500 J/kg with 0-6km bulk shear ranging from 30-45kt. This line of storms will cross through the CWA through this afternoon into this evening with the severe threat largely over by around 10 pm MDT. As stated, shear will be supportive of rotating updrafts. Mid-level lapse rates of around 6-8 C/km and MU CAPE of 1500-2500 J/kg and inverted V profile are supportive of large hail and damaging wind gusts. An isolated brief tornado or two can`t be ruled out. Another threat for this afternoon will be locally heavy rainfall as PWAT values of 1 to 1.4" (150-175% of normal) advect into the region. Weak ridging builds into the region tomorrow resulting in a dry and seasonably warm day, the ridge flattens out by Wednesday and we`re put under mostly zonal flow through Friday before another weak ridge builds into the region. A few disturbances riding along the flow will result in periodic, near daily chances for thunderstorms after Tuesday. In terms of temperatures, we will warm up through the week with highs generally near to just above average. Wednesday looks to be the warmest day of the week with highs reaching the upper 80s with south central SD potentially seeing highs in the low 90s. Temps cool off slightly but remain near to slightly above average through the end of the week. && .AVIATION...(For the 18Z TAFS Through 18Z Tuesday) Issued At 1030 AM MDT Mon Jun 10 2024 Local MVFR cigs over the Black Hills will continue to dissipate late this morning. A few high based showers/storms will continue into early afternoon but mainly VFR conditions will prevail. By 19Z-20Z, a cold front will move into the region, resulting in strong to severe thunderstorms developing over northeast WY and far western SD, then spreading eastward across western SD into central SD later this afternoon and early evening. IFR conditions likely in stronger storms along with large hail and damaging winds. Storms are expected to exit the CWA by 05Z, with VFR conditions returning, with relatively light westerly winds. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Wong AVIATION...Pojorlie