Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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912 FXUS63 KUNR 252020 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 220 PM MDT Wed Sep 25 2024 .KEY MESSAGES... - Dry weather, much warmer than average temperatures, and elevated to critical fire weather conditions continue through the weekend. - Cooler to start next week, then warming again. && .DISCUSSION...(This Evening Through Wednesday) Issued at 220 PM MDT Wed Sep 25 2024 Current surface analysis shows lee trough from central MT to central/eastern WY, with high pressure to the south of the region. Upper level analysis shows ridge covering the Rockies and high Plains. Skies are sunny with warm temps in the 80s to around 90 degrees in most areas. Winds are from the south to southeast, breezy across much of northeast WY into portions of western SD. A dry and warm pattern will continue through the weekend as ridging generally persists across the southwest US/Rockies into the Plains. Breezy south to southwest winds can be expected in some areas tonight into early Thursday, especially from northeast WY to southwest and south central SD. Thursday will be the warmest day of the work week, with highs reaching into the 90s across much of the plains. Some daily records could be broken, including in the Rapid City area. An upper level shortwave will pass mostly north of the region later Thursday and Thursday night, dragging a cold front across the forecast area during the afternoon and evening. This will bring breezy conditions and a slight cool down for Friday, with highs in the upper 70s and 80s, but little or no chance for pcpn. Ridge quickly returns to the region by the weekend, with highs in the 80s and 90s, warmest on Sunday. Elevated to critical fire wx conditions can be expected on most days through the weekend. Another trough is progged to quickly move from southwest Canada to south central Canada/northern Plains late this weekend into the beginning of next week. Main energy is expected to remain north of the forecast area Sunday night into Monday, so chances for any rain look minimal at this point, less than 15 percent. However, passing cold front will bring much cooler air and gusty winds for at least Monday, with highs back closer to average levels, 60s and lower 70s. Cooler air could linger Tuesday before weak ridging builds back into the region. Above average temps are likely mid to late week (60 percent or higher chances). && .AVIATION...(For the 18Z TAFS Through 18Z Thursday) Issued At 1129 AM MDT Wed Sep 25 2024 VFR conditions are expected through the TAF period. Breezy southerly winds will continue into tonight before transitioning to breezy northwesterly winds tomorrow morning. && .FIRE WEATHER... Issued At 220 PM MDT Wed Sep 25 2024 Critical or near critical fire wx conditions exist across the red flag warning area this afternoon, with humidity in the teens and wind gusts near or over 20 mph, especially across the northeast WY plains. Red flag conditions will continue in these areas until around sunset with poor humidity recovery and continued breezy conditions leading to elevated conditions overnight. Elevated fire wx conditions are noted across much of western SD this afternoon. For Thursday, the drier air will shift east with the ridge and ahead of an approaching cold front. Surface trough ahead of the front across western SD will bring increasing southwesterly winds later in the morning into the midday hours before the front arrives. The front looks to move through northeast WY and much of western SD during the midday and afternoon hours, stalling out toward central SD later in the day. Breezy conditions, gusts of 25 to 40 mph, look most likely behind the front over much of northeast WY and northwest into the west central SD plains during the afternoon (near or above 70 percent). Breezy south-southwest winds can be expected toward south central SD during the day. Humidity values will drop into the teens across much of the area, lower teens from much of northeast WY to southwest SD. Gustier winds may be more localized further south across southwest SD, but some gusts to near or above 20 mph are likely in many areas. With conditions expected to be critical or at least near critical over much of northeast WY and western SD, will issue a red flag warning for Thursday. For the area covered today with a red flag warning, poor humidity recovery and periods of breezy conditions can be expected tonight, so will just extend the warning out through tomorrow. Some cooler air and slightly higher humidity develop for Friday, with very warm conditions returning over the weekend. Elevated to near critical fire wx conditions persist through the period, with Sunday looking to be the most favorable day for red flag conditions. Another dry cold front will bring much cooler conditions and gusty winds into early next week. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Red Flag Warning from 10 AM MDT /11 AM CDT/ to 7 PM MDT /8 PM CDT/ Thursday for SDZ321-323>327-329-331>334. Red Flag Warning until 7 PM MDT Thursday for SDZ322. WY...Red Flag Warning until 7 PM MDT Thursday for WYZ314>317. && $$ DISCUSSION/KEY MESSAGES...26 AVIATION...Wong/Schultz FIRE WEATHER...26