Area Forecast Discussion

KEY MESSAGES

- Widespread rain tonight through early Tuesday, with the heaviest totals over central South Dakota and northern Black Hills.

- Strong northwest winds Monday and Monday night. Gusts of 45-55 mph expected, with localized gusts to 60 mph possible. - Rain changing to snow over the higher northern Black Hills Monday evening, with light accumulations.

- Drier weather returns later Tuesday and remains for the rest of the work week.

DISCUSSION

(This Evening Through Sunday) Issued at 234 PM MST Sun Nov 1 2026

Satellite/WV imagery shows a deep upper trough crossing the western CONUS, centered across the Great Basin, with very moist southwesterly flow increasing across the northern High Plains. Surface obs show low pressure strengthening across eastern WY into the CO Front Range. Southerly winds extending from TX to the Dakotas are pushing in plenty of moisture in the low levels. Still looks like the entire CWA will see precip from early this evening to early Tue morning as this large system crosses the north central CONUS. The three aspects of this storm we are resolving are QPF amounts, snow accumulation, and wind gusts. There is very good model agreement with widespread totals of 0.50" or more across the entire CWA. Models over the last 24 hours have settled on central SD receiving the most QPF, which could reach over an inch and a half or even 2 inches. Also, the northern Black Hills could see upslope- enhanced QPF exceeding two inches (some models suggest near 3 inches). Most other locations have a good chance of over an inch. This is an impressive system for early November bringing in PWATs over an inch...and approaching 1-1.5 inches over the eastern half of SD, which would be considered decently moist for the summer months. Given how dry early November is, that is 2-3 times higher than average. Upcoming soundings will show how well that verifies. Either way, the moisture is there for these high QPFs. Colder air will move in on the backside of the low during the day tomorrow. While the system will remain too warm for widespread accumulating snow, the higher elevations of the northern Black Hills should see minor accumulations (~2") after rain switches to snow Monday evening. Temps will be marginally cold enough in the evening for snow across the NE WY plains, but overall accumulation will be greatly limited by precip ending before sufficiently cold air arrives. However, minor accumulations along higher ridges can't be ruled out. Winds will increase behind the system as well, as the low closes up Mon afternoon with gusts of 45-55 mph or more expected across the NE WY plains and the western SD plains. The question remains just how strong the gusts will end up being. CAMs have been showing well above 50kt wind gusts across western SD. Interestingly, the 18z HRRR has dropped max gusts to 45-55mph, which is what prior shifts have been settling on. The exception is +50kt winds just east of the Black Hills into Fall River County. This lines up nicely with ensemble guidance. A High Wind Watch has been issued for most of the western SD plains given the potential for warning-level gusts, although portions of the watch area may ultimately warrant a Wind Advisory instead. Precip ends Tuesday morning, with drier and cooler (but near average) temps through mid week. Winds will be gusty early Tuesday but taper off through the day. Quiet weather is expected through the second half of the week.

AVIATION

(For the 18Z TAFS Through 18Z Monday) Issued At 1040 AM MST Sun Nov 1 2026

Expect continued widespread MVFR/IFR conditions with transient LIFR conditions at times through most of the period. While conditions may begin to slowly and temporarily improve to VFR early this afternoon, rain is expected to move into the region around 19-20z today with MVFR/IFR ceilings overspreading the area through the afternoon and evening hours and last through the remainder of the TAF period. Snow may mix in with the rain for KGCC starting around 02/13z.

Strong northwesterly winds will begin to increase across northeast Wyoming starting around 02/08-09z and across much of western South Dakota around 02/17-18z and last through the TAF period. Isolated gusts may reach 55+kts across the region. KRAP will likely see the stronger wind gusts, however, KGCC will also be impacted.

UNR WATCHES / WARNINGS / ADVISORIES

SD...High Wind Watch from Monday morning through late Monday night for SDZ001-002-012>014-025-026-030>032-041>043-072>075-077- 078. WY...None.