Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 010955
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
255 AM MST Thu Dec 1 2016

.SHORT TERM...(Today Through Friday Night)
Issued at 255 AM MST Thu Dec 1 2016

Storm system has finally moved away from the region, now centered
over the northern Great Lakes region. Current surface analysis
shows weak high pressure over southern SK into the northern high
plains. Upper level analysis shows general west-northwest flow
over the region behind exiting system. Weak shortwave energy noted
in analysis and water vapor imagery over the northern Rockies.
Local radar still showing isolated flurries over the western SD
plains, which should dissipate by daybreak. Regional radars show
areas of light snow and flurries over south central MT into north
central WY with the shortwave energy to the west. Skies are mainly
cloudy across much of western and south central SD, with some
clearing for the time being over portions of northeast WY and far
southwest SD. Temps are mostly in the 20s, with some teens over
cleared out areas. Winds are now less than 10 mph in most areas.

A somewhat unsettled pattern can be expected through Friday, with a
good amount of cloud cover around as weak shortwave energy crosses
the region. However, most areas will remain dry. A few snow showers
and flurries are expected at times, mainly across portions of
northeast WY, the Black Hills, and far northwest SD. Little or no
accumulation is expected in these areas, possibly a dusting over the
northern Black Hills and a few areas in northeast WY later today
into this evening. Temps will remain a bit below average, especially
across snow covered areas, with highs in the upper 20s and 30s today
and Friday. Warmest temps will generally be across snow free areas
of southwest SD. Lows will be in the teens to around 20 degrees each
night.

.LONG TERM...(Saturday Through Wednesday)
Issued at 255 AM MST Thu Dec 1 2016

Shortwave trough exits the CWA Saturday with northwest flow aloft
and a small warming trend into Sunday. A weak shortwave may bring
a few -SHSN to the higher terrain Saturday afternoon during peak
heating.

00z models continue to show arctic air pouring into the CWA Monday
night into the middle of next week. Model guidance is inconsistent
with a potentially problematic upper low developing somewhere across
central north America for the middle of the week. 12z/18z GFS from
yesterday show big storm possible near the CWA. 00z GFS shows an
upper low over south central Canada and a fast moving shortwave
moving across the southern Plains into the Midwest. 00z ECMWF
combines both systems into an upper low developing in MT Tuesday,
moving into the Midwest and winding up. Needless to say, won`t pin
pops on these vastly varying solutions. Exit of arctic air also
quite uncertain with ECMWF solution coldest into latter part of the
week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 255 AM MST Thu Dec 1 2016

Leftover IFR CIGS across far eastern reaches of the area will
move slowly east today. Mainly VFR conditions through the
forecast period elsewhere. A few -SHSN may develop over the higher
terrain this afternoon and evening with local MVFR conditions.
Local MVFR CIGS may also develop late tonight across northeast WY.

&&

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

$$

SHORT TERM...26
LONG TERM...Helgeson
AVIATION...Helgeson


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