019
FXUS63 KUNR 191120
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
520 AM MDT Wed Mar 19 2025

.KEY MESSAGES...

- Strong northwesterly winds across the western and south central
  SD plains today. Elevated fire weather conditions across south
  central SD

- Warmer and drier by Thursday with near critical to critical fire
  weather conditions across southwestern and south central SD

- Increasing chances for precipitation and breezy/gusty northwest
  winds late this week and over the weekend.

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 316 AM MDT Wed Mar 19 2025

Last vestiges of snow are moving out of the southern tier of the
CWA as the storm system slides to the southeast. Said system has
developed into a rather impressive 988 mb low centered over
Kansas. While the strongest lift has moved out of the region,
upslope flow and lingering moisture should support light snow
showers over the northern Black Hills and the northern and eastern
foothills through this morning.

Tight NW-SE oriented pressure gradient will support stiff
northwest winds this morning. Additionally, winds at 850-700 mb
will be at 30 to 40kt, which could mix down to the surface.
Widespread gusts of 35- 40 mph are likely (HREF probs of 70-100%)
across the western SD plains south of I-90. A few spots in south
central SD may approach advsy level gusts, however not too
confident that the stronger winds aloft will be able to mix down.
It doesn`t look like that much snow accumulated across south
central SD, which will translate to elevated fire wx conditions
this afternoon.

Weak upper level ridge builds over the region by Thursday,
bringing warmer and drier conditions to the CWA as west to
southwest downslope flow develops across the plains. This will
lead to near critical to critical fire wx conditions - especially
across southwestern into south central SD. See fire wx discussion.

Progressive and unsettled upper level flow will continue through
this weekend. Weak shortwave and attendant front will cross the
region Friday and bring the next chances for precip to the region.
Moisture and forcing associated with this system doesn`t look as
impressive as the last, but we could see some light precip, mainly
north of I-90 and across the northern Black Hills (LREF depicts
50- 80% probs of 0.01+" QPF). So far it looks like the precip will
be snow across the Black Hills and rain/snow over the plains.
2-3mb pressure rises behind the front will support gusty northwest
winds across the western SD plains Friday morning and afternoon.
The next and possibly stronger shortwave will tentatively move
across the region late Saturday. If you couldn`t tell by the word
choice in the previous sentence - confidence in exact timing,
strength, and associated impacts is still very low. There`s still
a lot of run-to- run variability with the deterministic models,
though the GFS has been trending further north and faster.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 516 AM MDT Wed Mar 19 2025

MVFR/IFR conditions will persist this morning across parts of the
area, with a few snow showers expected across northeast WY and
the the Black Hills through mid morning. Conditions will trend
VFR all places by the afternoon. Expect gusty NW winds mainly on
the Plains from the Black Hills south and east.

&&

.FIRE WEATHER...
Issued At 316 AM MDT Wed Mar 19 2025

Gusty northwest winds, dry conditions, and minimal snowpack will
lead to elevated fire wx conditions and very high grassland fire
danger across south central SD today. Afternoon RHs across south
central SD today will drop to 25 to 35% with northwest winds of 15
to 25 mph, gusting up to 40 to 45 mph.

Near critical to critical fire wx and high to extreme grassland
fire danger is possible across southwestern into south central SD
on Thursday. Gusty west-southwesterly winds will develop across
the area Thursday. Downsloping will support dry and warm
conditions across the western SD plains. Afternoon RHs across
southwestern into south central SD on Thursday will drop to 15 to
20 percent with winds of 20 to 30 mph, gusting up to 45 mph.

&&

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

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...15
FIRE WEATHER...Wong