051
FXUS63 KUNR 232320
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
420 PM MST Thu Jan 23 2025

.KEY MESSAGES...

- Another clipper drops through the area Friday with light snow
  and gusty winds
- Chilly temperatures this weekend replaced by a warming trend
  next week

&&

.DISCUSSION...(This Evening Through Thursday)
Issued at 1239 PM MST Thu Jan 23 2025

19z surface analysis had stationary front from central MT into
western KS. Water vapour loop depicted shortwave exiting the CWA
with subsidence/drying in it`s wake. However, another clipper was
lurking over western Canada, which will be the main weather maker
in the short term.

Tonight/Friday, clipper zips into the northern plains with warm
air advection ahead of it tonight potentially leading to patchy
light snow. Cold front drops in Friday with gusty northwest winds
(50% chance 35-45mph gusts) behind it as well as a band of light
snow. Froude numbers indicate favorable upslope environment for
the Black Hills for 6-9 hours, but 0-2km mean RH marginal for
notable enhancement (70%+ chance of 1-2" of snow). Best synoptic
forcing over northeastern WY, but moisture not that exciting.
Patchy blowing snow expected, particularly when coincident with
falling snow. Temperatures will be near guidance.

Saturday, modified arctic front slips into the CWA under
northwest flow aloft. MaxT Saturday 10-20F below normal with gusty
northwest winds again. Wind chills from 0 to -15F expected.

Sunday through next week, flattening upper ridge slips eastward
into the northern plains supporting some westerly downslope flow
and warmer temperatures. How warm will be determined by 1)
snowcover, and 2) any backdoor cold fronts that like to sneak onto
the western SD plains this time of year.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 417 PM MST Thu Jan 23 2025

Some lingering MVFR ceilings persist across south-central SD
(Martin to KICR), but this area should improve to VFR after 00-01z
this evening. Elsewhere, VFR conditions are expected now through
08-10z Friday morning ahead of the next system. As this system
moves in, MVFR/transient IFR conditions in low clouds and light
snow will return to northeastern WY and portions of far western
SD/Black Hills through the day Friday.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...SE