109
FXUS63 KUNR 191122
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
422 AM MST Wed Nov 19 2025

.KEY MESSAGES...

- Areas of fog...locally dense...across the northwest this
  morning

- Weak cold front passing through today will bring slightly
  cooler temps Thursday

- Temperatures to remain above seasonal norms into the weekend

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 223 AM MST Wed Nov 19 2025

Latest analysis shows weak 500 hpa and 700 hpa waves moving
through northwest SD this morning, with subsidence seen on
backside as evidenced by clearing skies across northeast WY.
Further west, there is a larger closed 500hpa low spinning across
southern CA with another 500 hpa trough moving through eastern
WA/OR in split flow regime. At the surface, low pressure is
located in east-central MT with a trailing front into southwest WY
and an inverted trough nosing northeast into southeast SK. Radar
imagery is showing any light pcpn has pushed east out of CWA, and
low clouds/fog remain entrenched over the northern counties and
the RC airport at 09Z.

The subsidence behind the exiting wave, combined with the passing
cold (cool?) front will help to erode the stubborn low clouds/fog
this morning, resulting in partly cloudy skies for most areas this
afternoon. Its hard to define the front as a cold (cool?) front
when expected highs today will be warmer than yesterdays high
temperatures, and still above seasonal norms. Cooler air does
filter into the area for Thursday, with 850hpa temps falling from
+10C today to around +6C for Thursday.

Temps make a rebound on Friday and Saturday before another weak
cool front moves through during the day Saturday, resulting in
slightly cooler temperatures on Sunday. With split flow regime,
the southern stream remains active one with all precipitation
staying south of the region leaving us mild and dry through the
period.

As one begins to ponder next weeks weather, turkey, dressing and
all the fixings, it continues to look like the coldest air so far
this season will make a grand entrance mid-week next week. It
could be a shock to the system as we go from the above seasonal
norms weve been enjoying lately, to well below normal temps next
week. Stay tuned as we dial that in as we get closer.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 418 AM MST Wed Nov 19 2025

Areas of fog with MVFR/IFR cigs/vsbys will persist across parts of
NW South Dakota and the western South Dakota plains through 18/15Z
before dissipating. Once the fog has dissipated, VFR conditions
are expected through the remainder of the valid TAF period.  into
Wednesday morning, mainly over northwestern SD.

&&

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

$$

DISCUSSION/KEY MESSAGES...Hintz
AVIATION...Hintz