Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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379 FXUS63 KUNR 270435 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1035 PM MDT Thu Sep 26 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 Thursday) Issued at 230 PM MDT Thu Sep 26 2024 Current surface analysis shows cold front from central ND to northwest SD to far northeast WY, moving slowly to the southeast. Surface trough is in place from north to south across central SD. Upper level analysis shows ridge now to the east of the region, with a shortwave trough located over the northern Rockies, moving to the northeast. Skies are sunny with unseasonably hot temps, mostly in the 90s across the plains, with 80s over the Black Hills. Some daily high temp records will be broken, including in the Rapid City area. The strongest winds are toward central SD, near the surface trough, with gusts to 40 mph from the south to southwest. Further west, areas of breezy conditions from the west to northwest are noted, especially near and behind the front. With very low humidities, red flag or near red flag conditions are affecting much of the area this afternoon. Dry and warm weather continues through the rest of the week and the upcoming weekend as southwest US ridge builds back north and east across the region. Shortwave trough passes well north of the region tonight into Friday as cold front slowly moves southeast into this evening, stalls out tonight over southern portions of SD, and then shifts back north and east on Friday. Friday will be about 10 degrees cooler in most areas, but still well above average for late September. However, temps will rise again over the weekend, with Sunday temps similar to today. Elevated to at least near critical fire weather conditions can be expected Friday through Sunday, with Sunday the most favorable day for critical fire wx conditions. The next cold front will likely arrive sometime Sunday night, with much cooler air accompanying that one, along with gusty winds. Associated upper level trough will slide across the northern Plains late Sunday night and Monday, but system looks moisture starved. Chances for any rainfall still look to be 10 percent or less at this point. High temps will finally drop back to near average levels, mostly 60s and lower 70s, for Monday and Tuesday. Zonal flow aloft/weak ridging will develop behind the trough toward midweek, with above average temps returning for at least Wednesday. Latest ensemble output is showing good potential for another upper trough and cold front arriving sometime late week and this one could bring at least a chance for pcpn. && .AVIATION...(For the 06Z TAFS Through 06Z Friday Night) Issued At 1035 PM MDT Thu Sep 26 2024 VFR conditions are expected through the TAF period. && .FIRE WEATHER... Issued At 230 PM MDT Thu Sep 26 2024 Red flag or near red flag conditions are in place across much of the area this afternoon, especially over the northeast WY and far western SD plains. Passing surface trough and cool front are bringing breezy west to northwest winds in these areas, with humidity values in the low to mid teens. Conditions will start to improve toward sunset. Some cooler air and slightly higher humidity are in place for Friday, but elevated fire weather conditions are expected in many areas Friday into Saturday and likely near critical over portions of northeast Wyoming. Very warm to hot conditions return over the weekend, especially on Sunday. Sunday looks to be the most favorable day for red flag potential as south to southwest winds increase ahead of approaching cold front. Minimum humidity is forecast to drop into the teens in most areas. Will continue to monitor potential over the next couple of days. Another dry cold front will bring much cooler conditions, higher humidity, and gusty winds into early next week. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...26 AVIATION...Wong FIRE WEATHER...26