Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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375 FXUS63 KUNR 261708 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1108 AM 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. - No appreciable precipitation through the middle of next week. && .DISCUSSION...(Today Through Wednesday) Issued at 153 AM MDT Thu Sep 26 2024 The warm, dry upper ridge over the area will shift southeastward as an upper trough crosses to the north of the forecast area this afternoon/evening. A surface trough, currently located over eastern MT/WY will shift eastward into western SD today, followed by a cold front later this afternoon. The warm and dry weather patter will continue through the weekend as the upper ridge rebounds behind the passing upper trough. Much warmer than average temperatures are expected today, with highs reaching well into the 90s across much of the plains. Some daily high temperatures records could be broken, including in the Rapid City area. Breezy to windy southerly winds will occur to the east of the surface trough this morning, with winds becoming southwesterly as the trough passes through, then later this afternoon/evening, the winds will become northwesterly as the cold front arrives. The very warm temperatures and dry air will drop the minimum relative humidity percentages into the lower teens this afternoon. Due to the expected warm, dry and windy conditions, a Red Flag Warning has been issued for most of the forecast area today. Behind the cold front, Friday will be only slightly cooler, with highs in the 80s over much of the plains. With the upper ridge then rebounding, very warm conditions will return for 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 will cross the Canadian prairie provinces this weekend into the beginning of next week. The main energy is expected to remain well north of the forecast area Sunday night into Monday, so any chances for any rain look minimal at this point. However, a passing surface cold front will bring much cooler air and gusty winds to start next week, with highs back closer to average levels in the 60s and lower 70s. Cooler air could linger into Tuesday before weak ridging builds back over the region. Above average temps are likely again for the second half of next week. && .AVIATION...(For the 18Z TAFS Through 18Z Friday) Issued At 1106 AM MDT Thu Sep 26 2024 VFR conditions are expected through the TAF period. Locally gusty south/southwest winds will persist into the afternoon ahead of a cold front, mainly across southwestern into south-central South Dakota. As the front sags southward and mixing picks up, winds will shift NW this afternoon with gusty winds continuing through the evening. && .FIRE WEATHER... Issued At 153 AM MDT Thu Sep 26 2024 Dry air will overspread the area today ahead of a cold front. A 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 cold front will cross northeastern Wyoming and much of western South Dakota during the midday and afternoon hours, stalling out toward central SD later in the day. Breezy conditions, with gusts of 25 to 40 mph, look most likely behind the front over much of northeastern Wyoming and the northwestern into the west central South Dakota plains during the afternoon. Over south central South Dakota, breezy south-southwest winds can be expected during the day. Humidity values will drop into the lower teens across much of the area. Gustier winds may be more localized further south across southwestern South Dakota, but some gusts around or above 25 mph are likely there. With conditions expected to be critical or at least near critical over the plains of northeastern Wyoming and western South Dakota, a Red Flag Warning is in effect today into this evening. Cooler air and slightly higher humidity will develop for Friday, with very warm temperatures returning over the weekend. Elevated to near critical fire weather conditions will continue through the period, with Sunday looking to be the most favorable day for a return to 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 until 7 PM MDT /8 PM CDT/ this evening for SDZ321>335. WY...Red Flag Warning until 7 PM MDT this evening for WYZ314>317. && $$ DISCUSSION/KEY MESSAGES...10 AVIATION...SE FIRE WEATHER...10