584
FXUS63 KUNR 281743
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1043 AM MST Fri Feb 28 2025

.KEY MESSAGES...

- Critical fire weather conditions across south central SD
  this afternoon

- Gusty northwest winds today (gusts of 40+ mph
  across western/central SD plains)

- Warm and dry weather will result in elevated fire weather this
  weekend

- Cooler and more active pattern arrives late Monday and
  continues through at least mid-week

&&

.DISCUSSION...(Today Through Thursday)
Issued at 227 AM MST Fri Feb 28 2025

Water vapor imagery depicts Pacific moisture associated with a
shortwave riding over the western CONUS ridge and spilling into
the Northern Plains. Associated sfc low now sits over northern MN
with sfc obs depicting the attendant frontal boundary pushing
through western SD. Northwest winds behind the front are breezy
with stations reporting gusts of 25 to 35 mph. Winds will pick up
again this afternoon with forecast soundings depicting a well
mixed boundary layer extending up to ~800 mb. With winds of 35 to
45kt at the top of the layer (~850-775mb), could see gusts of 45-
50 mph mixing down to the surface across south central SD. Will
keep the Wind Advisory. Given the dry (min RHs ranging from 25 to
30%) and unseasonably warm conditions (temperatures in the upper
50s to low 60s), have opted to hoist a Red Flag Warning for south
central SD (see fire wx discussion).

Shortwave will move out of the region by Saturday with
strengthening western US ridge dominating the pattern through the
weekend. This should keep conditions unseasonably warm (highs 10
to 20F above average) and dry with light winds.

By late this weekend, deterministic runs depict an upper low
developing over northern CA and swinging through the Rockies
before ejecting over the plains by late Monday/early Tuesday.
Attendant sfc low as of now looks like it will be to our south,
which would keep the majority of the precip to the south. Precip
should start off as rain before transitioning to snow as colder
air moves into the region. Latest LREF has backed off on precip
amounts and paints the highest probs (30-50%) of QPF exceeding
0.1" across the southern CWA, northern Black Hills, and portions
of northeastern WY. This could change if the track of the low
shifts further north.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1043 AM MST Fri Feb 28 2025

VFR conditions are expected through the period. Gusty northwest
winds will continue this afternoon, gusting to 35-45kts east of
the Black Hills. Winds will quickly diminish early this evening.

&&

.FIRE WEATHER...
Issued At 227 AM MST Fri Feb 28 2025

Critical fire weather conditions are expected across south
central SD this afternoon. While RHs will be above critical
thresholds (25 to 30%), the strong northwest winds (gusts of 45 to
50 mph), receptive fuels, and unseasonably warm conditions (upper
50s to low 60s) will support the development of critical fire
weather conditions across south central SD this afternoon.
Elsewhere across the western SD plains into northeastern WY,
elevated to near critical fire wx conditions are possible this
afternoon. Above average temperatures and low relative humidities
will continue to support elevated to near-critical fire weather
conditions through Sunday. Winds, however, will be lighter which
will preclude the development of critical fire weather conditions.

Winds will pick up again on Monday as a storm system approaches the
region, though relative humidities are expected increase as moisture
associated with said storm system moves into the region.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 5 PM MST /6 PM CST/ this afternoon for
     SDZ043-044-046-047-049-077.
     Red Flag Warning until 5 PM MST /6 PM CST/ this afternoon for
     SDZ333>335.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...13
FIRE WEATHER...Wong