495 FXUS63 KUNR 200918 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 318 AM MDT Mon Oct 20 2025 .KEY MESSAGES... - Strong northwest winds expected today, with gusts of 45+ mph across the western SD plains - Showers this afternoon could produce locally stronger wind gusts - Dry weather and a gradual warming trend for the rest of the week && .DISCUSSION...(Today Through Sunday) Issued at 318 AM MDT Mon Oct 20 2025 Water vapor imagery shows an upper trough crossing the northern High Plains. The main axis is centered over eastern MT into northeast WY. Surface obs shows a strong cold front has pushed through the CWA, as low pressure strengthens over north central SD, now approaching ABR. Strong gusts to 50-65 mph yesterday evening directly behind the frontal boundary (near the surface low) has moved eastward toward the Missouri River Valley. Northwest winds will continue today and tonight...increasing this morning, especially across the western SD plains. Forecast profiles show winds of 40-50kt transferring to the surface, given the steep lapse rates and weak cold air advection. It still looks like the strongest winds will be across NW SD, with gusts to 60 mph possible. Have upgraded the High Wind Watch to a High Wind Warning across the northwest SD plains, north of the Cheyenne River. Much of the rest of the SD plains, including the foothills, could see gusts of 45-55 mph, even down to the Fall River plains. The only exception will weaker winds across the leeside of the Black Hills, which includes the Custer plains into Oglala Lakota County. The steep lapse rates will also support late afternoon showers (and a few isolated thunderstorms) from NE WY through the northern Black Hills and NW SD. It is possible some of these showers could further mix down winds, supporting isolated gusts to 60 mph, even where there is no High Wind Warning. Winds will decrease this evening, so all headlines will expire at 03z. Tonight...a second wave will rotate down the backside of the upper low, mainly crossing central ND and East River SD. While headlines are not needed for the overnight hours, this wave will keep gusty over NW/central SD through the early Tuesday morning hours. Upper ridging will build in for the rest of the work week into the weekend, bringing several days of dry weather. A gradual warming trend is also expected, with temperatures in the 50s and 60s through midweek, then 60s and 70s for the second half. && .AVIATION...(For the 06Z TAFS Through 06Z Monday Night) Issued At 1114 PM MDT Sun Oct 19 2025 Mainly VFR conditions are expected through the period. A strong cold front will exit the area tonight. A short period of wind gusts from 30-50kt will occur just behind the front with a few showers, some of which may contain local MVFR conditions. Winds will then subside some, but pick back up again after 20/15z with gusts in excess of 45kt likely from northwest to south-central South Dakota. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...High Wind Warning from 8 AM this morning to 9 PM MDT this evening for SDZ001-002-012>014-073-078. Wind Advisory from 8 AM MDT /9 AM CDT/ this morning to 9 PM MDT /10 PM CDT/ this evening for SDZ025>027-031-032-041-043-044- 046-047-049-072-074-075-077. WY...None. && $$ DISCUSSION/KEY MESSAGES...13 AVIATION...Helgeson