Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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852 FXUS63 KUNR 030432 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1032 PM MDT Thu May 2 2024 .KEY MESSAGES... -Cool and unsettled through Friday -Breezy/windy and warmer this weekend, with potential for high winds on Sunday -Strong storm early-mid next week with windy/wet conditions && .DISCUSSION...(This Evening Through Thursday) Issued at 1251 PM MDT Thu May 2 2024 Water vapor shows main upper low near the SASK/MT border with distinct short wave over the Dakotas, and next upstream short wave over OR. At the surface, broad low covers ND with gusty westerly flow across our area. Very steep lapse rates attributing to scattered showers generally near/north of I-90 early this afternoon. Showers and wind will diminish quickly with loss of insolation early this evening. Next upstream short wave (currently over OR) will quickly shift into southern ID overnight and may bring a few showers to our southwestern zones towards morning. Showers will become more likely on Friday as short wave across WY and towards western NE by later in the day. Best forcing will be across our southern 2/3rds of zones, but lack of deep moisture should keep qpf under 0.25 in south-central SD and under 0.10 across the rest of the area. Thermal profiles continue to remain cold enough for some snow across the Black Hills and northeast WY but any accumulations should remain minor. Dry and warmer weather expected on Saturday with surface high over the Dakotas and upper ridge over the Rockies. Even warmer on Sunday with thermal ridge overhead, with highs in the 60s/70s. However, a very impressive surface pressure gradient between ridging over the Upper Midwest and trof coming off the Rockies will likely result in strong southerly winds across the area and wind highlights may become necessary. Strong upper low shifts from the Great Basin on Sunday into the Central Rockies on Monday, then lifting north into the Northern Plains on Tuesday. Showers/storms will become likely by late Sunday in our western zones, with continued very unsettled weather through early-mid next week as upper low becomes somewhat cut-off across the Northern Plains. Determinstic and ensemble solutions continue to wobble around with the placement of the upper low, which have big impacts on qpf amounts. Confidence for significant qpf is highest over our northwest zones, including the northern Black Hills, and lowest across our southern zones. NBM probabilities for greater an inch are in the 40-60 percent range generally north of I-90 as well as the Northern Black Hills and 15-30 percent further south. && .AVIATION...(For the 06Z TAFS Through 06Z Friday Night) Issued At 1028 PM MDT Thu May 2 2024 VFR area wide overnight with areas of MVFR/LCL IFR conditions associated with -RA/-SN encroaching on the southern portions of NE WY and SW SD into western SD after 12z as another disturbance passes through from west to east. Conditions will gradually improve to VFR from west to east late in the TAF period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Johnson AVIATION...Wong