395
FXUS63 KUNR 022011
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
211 PM MDT Tue Sep 2 2025

.KEY MESSAGES...

- Cold front moves through this evening and could bring some
  isolated thunderstorm chances

- Increasing smoke and haze by tomorrow afternoon

- Dry secondary cold front Thursday will bring gusty northwest
  winds around 40 mph

&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 144 PM MDT Tue Sep 2 2025

Large amplitude ridge continues to sit across the four corners
with the eastern edge of this ridge axis shifting east into the
Front Range. Upper level moisture is spilling over the top of the
ridge axis so we should an increase of high clouds into the
evening. We are tracking an upper low as it moves into the midwest
region and this low will push frontal boundary into western SD
late this afternoon. Upper air soundings show minimal instability
available with a pretty decent cap in place. With the remaining
low level moisture still hanging out across the Black Hills the
passing frontal boundary could be the focal point for some
isolated thunderstorm development this evening.

Behind the frontal boundary and with a shift to a northwest flow
and active fires across Montana and western Canada we will see an
increase in smoke and haze across the region tomorrow afternoon.
Smoke looks to be mainly aloft so we shouldn`t see any air quality
and or visibility degradations. Temperatures tomorrow will be
much cooler compared to the temperatures we experienced on
Tuesday.

Temperatures will rebound on Wednesday but we will be tracking
another cold frontal passage that will push through the region on
Thursday. This will be a dry frontal passage as this could be a
backdoor cold front that comes in from the east. The main concern
with this frontal passage will be the development of gusty
northwest winds across the eastern Plains and portions of the
Black Hills. Ensemble members are trending slightly higher in the
area seeing Wind Advisory level wind gusts Thursday afternoon. If
this pattern holds or the wind forecast increases, expect the
issuance of a Wind Advisory to be issued to account for this
hazard.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1104 AM MDT Tue Sep 2 2025

Mainly VFR conditions are expected through the period. A cold front
moves through tonight, bringing some smoke southward from Montana
and Canada. Isolated to scattered showers and thunderstorms are
possible after 22Z.

&&

.FIRE WEATHER...
Issued At 144 PM MDT Tue Sep 2 2025

A dry cold front will move through Thursday. Minimum relative
humidities will dip into the 20s with gusty northwest winds
potentially exceeding 40mph The concern is for elevated fire
conditions to develop across eastern Wyoming and the southwestern
corner of South Dakota.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Woodward
AVIATION...Smith
FIRE WEATHER...Woodward