532
FXUS63 KUNR 142321
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
421 PM MST Thu Nov 14 2024

.KEY MESSAGES...

- Mild and dry weather continues Friday

- Weak system Saturday expected to bring cool and breezy conditions,
along with chances for rain/snow

- Potentially active pattern in store next week with much colder
  and windy weather

&&

.DISCUSSION...(This Evening Through Thursday)
Issued at 1248 PM MST Thu Nov 14 2024

Broad upper ridging covers the western 2/3 of the CONUS, while a
trough approaches the west coast. At the surface, a trough is
moving through the Dakotas. Winds are southwesterly, and
temperatures are warming into the 60s. Skies are mostly sunny.

On Friday, the west coast upper trough will move ashore, and the 850
mb low will move over the Rockies.  With southeasterly flow over the
CWA, cooler air will advect in. Highs will be in the 50s, under
mostly cloudy skies.

Friday night, the upper trough begins to split, and the 850 mb low
slides into the northern plains. Most of the precip associated with
this wave will be across MT/ND, although some light rain/snow may
skirt our NW CWA Saturday. This low will drag a cold front into our
area, resulting in breezy NW winds and cooler temps. Highs Saturday
will range from the 30s across the Black Hills, northeastern WY, and
northwestern SD, to the 50s across south central SD.

This northern wave will exit the region Sunday, while the southern
portion of the trough deepens as it digs into northern Mexico.
Deterministic models show the low swinging up to the central states
Monday, while another wave sweeps in from the west. Our weather next
week will depend on how and where these lows interact. So far the
farther east in SD you are, the more likely you are to receive
impactful weather. The 12Z ECMWF deterministic and ensemble
solutions continue to bring more snow to our CWA than the
GFS/Canadian solutions. Still, the ECMWF ensemble has only about a
60% chance of the western SD plains receiving an inch or more,
with the northern BH at a 60% chance of receiving 3+ inches. Will
continue to watch how this system evolves. Of more certainty than
precipitation is that cold and blustery conditions can be expected
early to mid week.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 421 PM MST Thu Nov 14 2024

VFR conditions should persist through the period. Breezy east to
southeast flow will develop by 18z over much of the region, with
some gusts to around 30 kt not out of the question. In areas where
dense cloud cover precludes mixing tomorrow morning/early
afternoon, low-level wind shear could develop.

&&

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

$$

DISCUSSION/KEY MESSAGES...Pojorlie
AVIATION...Sherburn