Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 242329
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
429 PM MST Tue Jan 24 2017

.SHORT TERM...(This Evening Through Wednesday Night)
Issued at 143 PM MST Tue Jan 24 2017

Potent shortwave trough and associated jet streak continuing to
support snow across much of the region, esp across south central
SD. Strong FGEN/WAA/convectively enhanced snow banding ongoing
there and will continue through much of the evening. Drier and
colder air staring to filter into the region from the NW, with
snow crystal production efficiency starting to wane significantly.
Most places in NE WY and around the Black Hills have revived the
majority of their snowfall from this system with only an inch of
two additional snowfall expected there. Winds are much weaker that
previous expected with blowing snow expected to be confined to the
SD plains. Hence, adjustment to the headlines was made, canceling
the adv over NE WY outside the Black Hills, with a downgrade to
the warning over the northern Black Hills. Main snow show will
continue to be scentral SD where total snowfall amounts of 8-15
inches are expected given mesoscale banding, sufficient moisture,
and efficient dendritic snow growth.

Otherwise, the storm system will exit the region tonight, with
lingering snow over scentral SD. Moist cyclonic flow will support
a chance for light snow showers across the NW third Wed. Cloudy
skies will persists with general troughing around with some
clearing expected over the far west Wed night. Temps 5 to 10
degrees below seasonal norms can be expected through the period.

.LONG TERM...(Thursday Through Tuesday)
Issued at 143 PM MST Tue Jan 24 2017

A broad upper level trough will remain across the
central to eastern half of the US late in the week, with a highly
amplified ridge over the west coast. North-northwest flow aloft will
remain over the Rockies and Plains. Weak disturbances within this
flow will bring clouds and brisk winds at times, along with a few
isolated snow showers mainly this weekend. Temps will remain below
average Thursday, with a gradual warmup to near average temperatures
over the weekend as ridge slowly shifts eastward into the Rockies
region.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 426 PM MST Tue Jan 24 2017

LIFR conditions due to SN/BLSN southeast of KRAP will continue
this evening with slow improvement to IFR overnight and then MVFR
Wednesday. IFR conditions due to SN/BLSN over northeast WY and
northwest into southwest SD will continue this evening with
improvement from northwest to southeast overnight into Tuesday
with areas VFR conditions developing.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 11 PM MST this evening for
     SDZ024>026-028-029-072-074.

     Winter Storm Warning until 5 AM MST /6 AM CST/ Wednesday for
     SDZ027-030>032-041>044-046-047-049-073.

     Winter Weather Advisory until 5 AM MST Wednesday for SDZ012>014.

WY...Winter Weather Advisory until 11 PM MST this evening for WYZ057-
     071.

&&

$$

SHORT TERM...JC
LONG TERM...13
AVIATION...Helgeson



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