Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 120904
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
204 AM MST Tue Dec 12 2017

.DISCUSSION...(Today Through Monday)
Issued at 202 AM MST Tue Dec 12 2017

Northwest flow continues over the northern plains, with a
persistent upper ridge to the west and trough to the east. A band
of low clouds and a warm front stretch from north to south across
the central/eastern Dakotas. Under mostly clear skies, the CWA has
light westerly surface winds and temperatures in the 20s.

Warm air advection and sunny skies will allow temperatures to warm
into the 50s and lower 60s again today. Winds will be fairly light,
around 5 to 15 mph.

Another fast-moving shortwave will push through the northern plains
tonight. The ECMWF and GFS are in better agreement now on the track,
timing, and intensity of this system, which looks very similar to
the one Sunday night/Monday morning. CONSMOS is showing advisory
criteria winds for much of the western SD plains, but NAM and GFS
forecast soundings are showing 50+ kt winds mixing down again,
especially just east of the Black Hills. This is supported by
another 5-6 mb pressure difference over the Hills with 40-50 kt
boundary layer winds. The strongest winds are expected to be late
tonight into Wednesday morning with the strongest CAA and pressure
rises. Will put out a High Wind Watch for the areas just east of the
Black Hills for now.  Highs Wednesday will cool to the 40s.

Yet another shortwave will cross the region Wednesday night into
Thursday morning, bringing a reinforcing shot of cold air and gusty
winds. Winds on Thursday don`t look quite as strong as
tonight/Wednesday; however, more moisture associated with this
system will bring a chance for some light snow. Highs Thursday will
be mainly in the 30s.

The upper ridge axis will shift over the region Friday, as a
stronger wave moves over the Pacific Northwest. Highs Friday will
warm back into the 50s, but chances for precip will increase Friday
night into Saturday as the wave crosses the Rockies. Highs this
weekend look to be in the upper 30s to upper 40s.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1015 PM MST Mon Dec 11 2017

Local MVFR ceilings from KHEI-KPHP-KICR will gradually dissipate
overnight. VFR conditions expected elsewhere.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Watch from this evening through Wednesday morning for
     SDZ026-031-072-073.

WY...None.
&&

$$

DISCUSSION...Pojorlie
AVIATION...7



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