034
FXUS63 KUNR 092009
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
209 PM MDT Sun Mar 9 2025

.KEY MESSAGES...

- Critical fire weather conditions Monday
- Gusty/strong northwest winds Monday
- Mild and dry through Thursday
- Strong storm possible for the end of the week, but impacts
  unsurprisingly continue to oscillate

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 159 PM MDT Sun Mar 9 2025

19z surface analysis had low over southern AB with lee trough
into WY. Water vapour matinee had upper ridge poking into the
northern Plains with cirrus spilling over it into the CWA. Day
snow/fog RGB depicted snowcover over a good chunk of northeastern
WY and then along the SD/NE border, which is shrinking on the
edges courtesy of temperatures in 60s outside of the snowcover.
40s in snowcover. Short term attention focused on upper trough
crashing into BC per water vapour.

Tonight/Monday, shortwave trough zips across southern Canada
breaking down upper ridge and pushing surface low southeast.
Trailing cold front develops, which will zip through the CWA
Monday afternoon. Westerly flow strengthens ahead of the front,
promoting continued dry/mild conditions. Behind the front, 850mb
winds ~40kts and 2-4mb/3hr pressure rises will bring gusty
northwest winds Monday afternoon. Best forecast pressure rises
northeast of the CWA. Bufkit forecast soundings suggest a high end
wind advisory most spots, although northwest SD may briefly gust
around 50kts. HRRR/NBM probabilities of 50kt gusts is less than
50%, so will continue the High Wind Watch. Temperatures will be
near guidance.

Tuesday through Thursday, mild/dry weather continues per
west/southwest flow aloft. Vigorous upper trough crashes into the
Rockies Thursday. Most guidance spins up vigorous upper/surface
low Friday over the central Plains, moving into the upper
Midwest. Important differences remain in the track of the storm
(especially Friday) as well as strength of the upper low. Major
differences in impacts as a result over the CWA. We are still in
the watching/waiting mode, meticulously pouring over each set of
ensemble guidance. Stay tuned.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1120 AM MDT Sun Mar 9 2025

VFR conditions are expected through the TAF period. Main aviation
concern will be the development of gusty westerly winds by 12-15z
across the terminals, where wind gusts will be between 25-35
knots.

&&

.FIRE WEATHER...
Issued At 159 PM MDT Sun Mar 9 2025

Dry conditions and above average temperatures are expected
through Thursday. Warm and dry weather Monday will drop relative
humidities to as low as 13-20 percent. Gusty westerly winds Monday
are expected ahead of a dry cold front, which moves through
Monday afternoon shifting winds to the northwest at 25-35 mph with
gusts around 55 mph. The strongest winds are expected across
northwest South Dakota. A Red Flag Warning has been issued to
account. Dry weather and light to moderate winds will persist
through midweek, continuing elevated fire weather conditions.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from 10 AM to 7 PM MDT Monday for SDZ323>325-
     327>332.
     High Wind Watch from Monday morning through Monday evening for
     SDZ001-002-012>014-078.
WY...&&

$$

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