320
FXUS63 KUNR 232339
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
439 PM MST Sat Nov 23 2024

.KEY MESSAGES...

- Critical fire weather conditions this afternoon across parts of
  northeast WY, with elevated fire weather conditions into the
  Black Hills

- Cold front Sunday with gusty northwest winds and chances of
  light snow/flurries for northeast Wyoming and Black
  Hills...light accumulations possible in the Black Hills

- Near to below average temperatures through mid week, with
  reinforcing shot of cold air Thanksgiving into the weekend. A
  bit of light snow at times

&&

.DISCUSSION...(This Evening Through Saturday)
Issued at 1225 PM MST Sat Nov 23 2024

Water vapor shows upper ridge over the Northern Plains and upper
low off the Pac NW coast, with distinct short wave ejecting into
western MT. At the surface, backdoor cold front is mostly south
and west of our zones, with the exception of southern Campbell
county and higher elevations of the Black Hills. Next upstream
cold front is over north central MT. Stratus/fog on the western SD
plains has been slow to break up with early afternoon temps still
in the 20s. A bit warmer in the Black Hills and parts of
northeast WY where southwest winds have returned.

Stratus/fog should continue to break up this afternoon with
backdoor cold front slowly lifting back northeast. Some fog may
reform again tonight on the western SD plains, but will dissipate
from west to east late tonight as upstream cold front moves in.

Gusty northwest winds expected Sunday behind the cold front. Have
trended pops a bit higher for the Black Hills and southwest SD for
Sunday and Sunday evening, with possibly an inch or two
accumulation in the Black Hills wherever the convergence boundary
sets up. At this time, it looks like the better chances for
accumulation will be over the central and southern Black Hills.

Flat upper ridge overhead early next week should lead to mostly
dry conditions with temps near to slightly below average. Next
trof swings through later Tuesday into Wednesday, and brings
another chance for light snow although moisture should remain
limited. Behind this trof, even colder air should swing into the
Northern Plains for Thanksgiving into the weekend. Could be a bit
light snow late in the week, but moisture will remain limited.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening)
Issued At 431 PM MST Sat Nov 23 2024

Areas of fog and low clouds with associated IFR/transient local
LIFR conditions will persist across portions of western SD
overnight ahead of a sfc trough. KRAP will be on the edge of the
low clouds and fog, with conds expected to improve late tonight
as the sfc trough moves through. Breezy southerly winds will
continue ahead of the trough with winds shifting NW behind the
trough, scouring out any remaining low clouds/fog. A clipper
system will bring some light snow to the SW half of the FA Sunday
afternoon, with MVFR conds in light snow expected there. Local IFR
conds will be possible in the Black Hills.

&&

.FIRE WEATHER...
Issued At 1225 PM MST Sat Nov 23 2024

Critical fire weather conditions have developed across parts of
northeast WY into the Black Hills northeast WY as very dry
southwest winds have moved in. Elevated to near critical fire
weather conditions may also spread into the Black Hills and parts
of far southwest SD this afternoon. A cold front will move through
the area Sunday with gusty northwest winds. Colder and unsettled
conditions are expected for much of next week, with chances for a
bit of light snow at times.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...Red Flag Warning until 6 PM MST this evening for WYZ315.
&&

$$

DISCUSSION/KEY MESSAGES...Johnson
AVIATION...JC
FIRE WEATHER...Johnson