Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 110912
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
212 AM MST Sun Dec 11 2016

.SHORT TERM...(Today Through Monday Night)
Issued at 209 AM MST Sun Dec 11 2016

Upper flow is nearly zonal across the CONUS, with a weak wave
pushing through the northern plains. Skies are mostly cloudy. Much
of the snow has already moved into eastern SD ahead of the trough,
with a little light snow lingering over the southwestern CWA. At
the surface, the trough is crossing western SD, and winds are
light. Temperatures at 2 AM are in the single digits and teens.

Trough will exit the northern plains today, and high pressure will
sink into SD. West-southwest low-level winds ahead of next low will
bring in warmer air, allowing temperatures to warm into the 20s and
30s across the southwestern half of the CWA. Areas farther north and
east will remain in the single digits and teens.

A Canadian low pressure system will begin dragging another cold
front through the region late tonight and into Monday. A quick-
moving band of snow will develop across northwestern SD along an
area of enhanced frontogenesis and upper divergence. Less than an
inch of accumulation is expected before high pressure moves back in
and pushes this band eastward, but there may be some patchy blowing
snow with the breezy northwest winds behind the front. There may
also be some light snow over the southwestern CWA Monday night along
the baroclinic zone. High temperatures will reach the teens and 20s
across the southern half of the CWA, before temperatures fall during
the afternoon. Northwestern SD will remain in the single digits,
with wind chills of 15 to 25 degrees below zero. Lows Monday night
will be 5 degrees above and below zero.

.LONG TERM...(Tuesday Through Saturday)
Issued at 209 AM MST Sun Dec 11 2016

Dry weather is expected on Tuesday and Wednesday due to
cold high pressure over the region. The surface high will shift off
to the east on Thursday. A weak shortwave will bring a slight chance
of light snow or flurries Thurs/Thurs night as WAA aloft overruns
the colder air at the sfc, ahead of a low pressure system developing
over Wyoming. The low pressure center will drop into northeastern
Colorado by Friday morning then will track eastward near the Neb/KS
border during the day on Friday. Another batch of even colder Arctic
air will be drawn southward into the forecast area on Friday night
and Saturday behind the departing low pressure system. Widespread
snow is expected across the region from Thursday night through
Friday night, with mainly dry weather again on Saturday.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Monday Morning)
Issued At 209 AM MST Sun Dec 11 2016

Areas of MVFR/LCL IFR CIGS will gradually improve to VFR
during the morning. VFR conditions will then continue through the
rest of today and into this evening. Areas of MVFR cigs in -SN are
possible over parts of northwestern SD aft 06Z tonight.

&&

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

$$

SHORT TERM...Pojorlie
LONG TERM...10
AVIATION...10



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