475
FXUS63 KUNR 012141
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
241 PM MST Sun Nov 1 2026

.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.
&&

$$

DISCUSSION...13
AVIATION...Schultz