Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 232337
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
437 PM MST Tue Jan 23 2018

.DISCUSSION...(This Evening Through Tuesday)
Issued at 103 PM MST Tue Jan 23 2018

Temperatures are running a bit above guidance this afternoon, a
trend that should continue through Thursday as upper-level ridging
builds into the Northern Plains. Aside from a few strong wind
gusts this afternoon over the SD Plains, generally quiet weather
is expected through Wednesday morning as weak high pressure shifts
over the area.

A deep trough over the Pacific Coast and associated surface
cyclone will begin to impact the Dakotas/northeast WY late
Wednesday into Thursday. A tightening pressure gradient Wednesday
afternoon through Thursday will provide strong winds over portions
of northeast WY and, subsequently, favored downslope regions of
the Black Hills. Given consistent model solutions depicting 850 mb
winds in excess of 50 kt, there is fairly high confidence that
portions of the Black Hills/Foothills will see some gusts
exceeding at least 35 kt. Winds should subside late Thursday as
pressure gradient weakens and higher pressure moves into the
region. Given downslope winds both Wednesday and Thursday, have
leaned toward the higher end of guidance for temperatures, which
should lead to some 60s across eastern portions of the Hills on
Thursday afternoon.

The cold front associated with the aforementioned cyclone and
its post-frontal airmass will have limited moisture, thus
providing scant precipitation. However, light rain/snow will be
possible across northeast WY/northwest SD on Friday morning, then
again over the weekend as we transition to northwest flow aloft.
Little to no accumulations or impacts are expected.

Beyond the weekend, warmer temperatures are again expected to
start next week as another ridge builds over the Plains. Our next
appreciable chance for widespread precipitation appears to be late
Tuesday into Wednesday as a trough digs into the central U.S.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 431 PM MST Tue Jan 23 2018

Relatively light winds and clear skies overnight tonight across
western South Dakota. Winds will increase and turn southerly over
northeast Wyoming after midnight. Otherwise, VFR conditions are
expected through the period.

&&

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

$$

DISCUSSION...Sherburn
AVIATION...Eagan



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