Area Forecast Discussion
Issued by NWS Rapid City, SD

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319
FXUS63 KUNR 021114
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
414 AM MST Fri Dec 2 2016

.SHORT TERM...(Today Through Saturday Night)
Issued at 236 AM MST Fri Dec 2 2016

Upper level analysis has broad trof over the northern CONUS with
close low over far southern California. Sharp ridge is located
along the west coast just ahead of another closed low in the Gulf
of Alaska. Skies are mostly cloudy across the northern Plains with
some very light snow showers and flurries over the Dakotas. At the
surface, high pressure has settled into the Dakotas with a weak
lee trof across central Montana and eastern Wyoming. Temperatures
at 2pm were in the 20s with relatively light winds.

Today...Broad trof remains across the northern CONUS with southern
Cal closed low dropping further south into Mexico. Skies will
remain mostly cloudy across much of the area this morning. Light
winds and light westerly upslope may produce some patchy fog along
the western edge of the Black Hills. Some patchy fog may be
possible across parts of the SD plains this morning where better
moisture is present. By late morning, might see some breaks in the
cloud cover over Northeast WY and far southwest SD as weak surface
trof shifts east. Temperatures will be warmest were the sun
manages to make it through the cloud cover, with a few locations
possibly seeing upper 30s. Most locations across the SD plains
will see highs right around 30 degrees.

Tonight...Weak upper trof axis slides into the western Dakotas
overnight as surface high pressure shifts east - and lee trof
strengthens. Light winds will become southwest across the area
overnight. Temperatures will fall into the teens to around 20
degrees under variably cloudy skies.

Saturday...Upper trof axis shifts east of the area as weak surface
trof moves through western SD. Winds will become more westerly
across northeast WY and far western SD, allowing slightly warmer
air to move in. Several locations across Northeast WY and
southwest SD could see temperatures rise to around 40 degrees,
while 30s hold across the SD plains north and east of the Black
Hills. Surface trof shifts into eastern SD Saturday night, with
slightly milder temperatures expected overnight. Lows will be in
the upper teens to mid 20s.

.LONG TERM...(Sunday Through Thursday)
Issued at 236 AM MST Fri Dec 2 2016

Westerly downslope flow will support temperatures a few degrees
above normal Sunday.

Monday, arctic front moves through the CWA as upper low/trough over
central/western Canada settles southward. Some light snow may occur.
Model guidance is coming to a consensus with evolution of this
system. Upper low/trough over south central Canada will keep
northerly flow over the CWA through Thursday - longer than previous
guidance had suggested over the past couple of days. Main southern
stream impulse won`t wrap up until it is well east of the CWA, so
any hope for notable snow accumulations is likely gone. Temperatures
will be 10-20F below normal and then moderate some in the west
Thursday and over the rest of the CWA Friday, although arctic air
may hold tighter over central SD.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 413 AM MST Fri Dec 2 2016

Some MVFR/IFR CIGS expected across the area this morning due to
patchy ST/FG along with a few flurries. Conditions will improve
most areas this afternoon with VFR CIGS expected.

&&

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

$$

SHORT TERM...15
LONG TERM...Helgeson
AVIATION...Helgeson



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