468
FXUS63 KUNR 052002
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
202 PM MDT Sun Oct 5 2025

.KEY MESSAGES...

- Areas of frost/freezing possible tonight and again Monday night.
- Showers possible over southern third of forecast area this evening.
- Warmer and dry Tuesday through the end of the week.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 200 PM MDT Sun Oct 5 2025

An upper level trough axis stretches from Saskatchewan through the Northern
Rockies and back into west-central California. Water vapor imagery
shows multiple shortwaves across the region, with one lifting north
of the forecast area this morning and additional waves further upstream.
Surface low pressure is centered over southwestern Ontario with a cold
front stretching southward through MN, eastern SD, and back into eastern
CO. Much cooler temperatures today behind the front with highs in the
40s to mid 50 along with gusty northwesterly winds. Showers will linger
through the afternoon, although precipitation amounts will be limited.
As the upstream shortwaves push through the area late tonight expect
additional showers, mainly across northeastern WY and southwestern SD.
Some snow may mix in across the higher elevations, although not expecting
any accumulations.

Main weather concern over the next 24-48 hours will be potential for
frost/freezing temperatures. Have issued a Freeze Warning for Harding
and Perkins counties for later tonight through Monday morning. Expect
skies to clear across far NW SD later this afternoon, resulting in
better radiative cooling and temperatures to fall below freezing,
better chances closer to the ND/SD border. Frost is possible across
the northeastern WY plains tonight, but cloud cover will linger, limiting
extent of cooling. Frost/freezing temperatures also expected again
Monday night into Tuesday morning with mostly clear skies across the
forecast area. Will likely need more frost or freezing headlines to
capture that threat.

Models are in good agreement with the upper trough pushing east of
the forecast area Tuesday with ridging returning across the central
and western US. Expect a gradual warm up Tuesday through the end
of the week with highs pushing back into the 70s to near 80 Wednesday
through Friday with mid 80s possible (~70%+ chance temperatures >
80F via NBM probs) across the western SD plains Saturday. Ensembles
are highlighting another upper trough over the western US by Sunday,
although considerable spread in timing and effects on temps/precip
remain. Regardless, expect cooler air and chances of precipitation
again beyond next weekend.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1058 AM MDT Sun Oct 5 2025

Isolated MVFR conditions in rain showers and gusty surface winds
of 15 to 25 KTs will continue though the evening. Another system
will bring MVFR- IFR conds across northeast WY into southwest SD
later tonight into Monday morning.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Freeze Warning from 1 AM to 9 AM MDT Monday for SDZ001-002-078.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...SE
AVIATION...Smith