268
FXUS63 KUNR 121119
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
419 AM MST Wed Feb 12 2025

.KEY MESSAGES...

- Very cold again today before a brief warmup Thursday, then arctic
air returns for the weekend

- Chances for light snow Friday and Saturday

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 159 AM MST Wed Feb 12 2025

Upper trough is digging into the Rockies, and a plume
of moisture emanating from the low is helping to produce snow over
much of NE, some of which is pushing into southern SD. The first
surface high has slid into MN, and then next one is pushing into the
Dakotas from MT. Skies across the northern CWA are mostly clear,
resulting in temps dropping below zero. With breezy northerly winds
gusting up to 20 kts, wind chills are in the 20s and 30s below zero
again across NW SD.

The cold high pressure will keep highs only in the single digits
today. Light snow across the south will dissipate, and skies will
clear from north to south. Under mostly clear skies, lows will dip
below zero again. Wind chills are expected to drop into the 20s and
30s below zero across NW SD again, and also across central SD.
Have extended the Cold Weather Advisory across NW SD to Thursday
morning, and have also issued a Cold Weather Advisory for the
central SD zones tonight into Thursday morning.

Transient upper ridging will build over the western CONUS Thurs, and
southwesterly winds will increase ahead of an approaching surface
trough. As warm air advects into the region, highs will reach the
20s and 30s (above zero!). Southern parts of the CWA may enjoy these
warmer temps again Friday, but a cold front will quickly put an end
to the warmer temps across the north. Highs Friday may range from
the teens across NW SD to the 40s across southern SD. Arctic airmass
is expected to keep temperatures cold at least through the weekend.
Messy upper level energy associated with the longwave trough will
cause some occasional snow Friday into Saturday, but
accumulations will be minimal.

Beyond this weekend, deterministic solutions keep us on the edge of
the cold airmass, and ensemble temperature spread increases. There
is the potential for the cold air to linger into early next week,
but confidence is low. Active pattern will keep chances for
occasional light snow around.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 417 AM MST Wed Feb 12 2025

Areas of MVFR/local IFR conditions will continue across parts of
northeastern Wyoming, the Black Hills, and northwestern South
Dakota today. VFR conditions are expected elsewhere.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Cold Weather Advisory until 8 AM MST Thursday for SDZ001-002-
     012>014-078.
     Cold Weather Advisory from 11 PM MST /midnight CST/ this evening
     to 8 AM MST /9 AM CST/ Thursday for SDZ032-043-044-046-047-
     049-077.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Pojorlie
AVIATION...7