Area Forecast Discussion
Issued by NWS Rapid City, SD

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418
FXUS63 KUNR 100957
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
257 AM MST Sun Dec 10 2017

.DISCUSSION...(Today Through Saturday)
Issued at 256 AM MST Sun Dec 10 2017

Upper ridging covers the western CONUS, while a trough
persists over the east. Skies across the northern plains are mostly
clear. Westerly surface winds are 15 to 25 kts with some gusts of
30+ kts, which is keeping temperatures in the mid 30s to mid 40s at
3 AM. Relative humidity in and around the Black Hills is only
around 15 to 20%.

Strong upper ridging will result in another warm and dry day today,
with highs in the 50s to mid 60s. Westerly winds will be breezy
again.

Tonight, a clipper will dive south through the northern plains.
Precip will stay east of the CWA for the most part; however, very
strong winds are possible. Most models are not picking up on this,
but forecast soundings from the NAM and GFS show 50-60 kt gusts
mixing down across northwestern to west central SD as early as 09Z.
The NAM is also showing a 6 mb pressure difference across the
Black Hills 06-15Z Monday, and strong CAA is expected. Have
issued a High Wind Watch for these areas from 06-21Z Monday. Highs
Monday will cool into the 40s.

Another warm front will allow temperatures to warm into the 50s
again for Tuesday. Models are still showing another clipper Tuesday
night into Wednesday morning, although the track of the GFS and
ECMWF still differ. Another round of gusty winds will be possible on
Wednesday. Mild temperatures are expected through the end of the
week. Dry weather will also continue until late Friday/early
Saturday, when a stronger wave brings a chance for some light
rain/snow.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Sunday Night)
Issued At 1035 PM MST Sat Dec 9 2017

VFR conditions will continue through Sunday afternoon. Low level
wind shear will develop over much of western South Dakota this
evening and will continue through tonight. Winds will be gusty at
times Sunday, especially across the South Dakota plains.

&&

.FIRE WEATHER...
Issued At 256 AM MST Sun Dec 10 2017

Temperatures will warm into the 50s and 60s today, and minimum RH
values will range from about 13% across southwestern SD to 30%
across northwestern SD. Breezy westerly winds will gust above 25
mph frequently across southwestern SD, the foothills, and areas
just east of the Black Hills. Have issued a Red Flag Warning
beginning early this morning, since some places are already
reaching criteria.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 5 PM MST this afternoon for SDZ260>264.

     High Wind Watch from this evening through Monday afternoon for
     SDZ001-002-012>014-026-031-032-043-072-073.

WY...None.
&&

$$

DISCUSSION...Pojorlie
AVIATION...7
FIRE WEATHER...Pojorlie



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