Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 221709
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1109 AM MDT Sun Oct 22 2017

.DISCUSSION...(Today Through Saturday)
Issued at 252 AM MDT Sun Oct 22 2017

Weak ridging has set up across the High Plains this morning with the
next bit of active weather moving into the Pacific NW. A weak
surface ridge is extending over the High Plains as the region sits
between Canadian low pressures. The Pac NW upper level disturbances
will cross the northern Rockies into the northern Plains today
bringing increasing clouds. With westerly low level flow, warm air
advection will develop over the next few hours with increasing temps
through the afternoon. Highs will reach the 60s to low 70s. Warmer
air will be very short-lived across the CWA as the next cold front
pushes through tonight. Some light showers are expected to
develop as the front crosses the area, but POPs/QPF will be low.
Winds will increase from the NW behind the front. Models have been
trending stronger with each run...and 00z runs are showing winds
increasing to advisory criteria across northwest SD as early as
before sunrise. Winds will continue to increase through the
morning hours with CAA and steep lapse rates. Winds may reach high
wind criteria particularly over the NW and west central SD
plains. Have issued a high wind watch for 14z Mon-02z Tue.

Strong upper ridging will develop across the western CONUS
Tue/Wed. A series of waves will weaken the ridge across the
northern Rockies and Plains late Wednesday...then dig
significantly into the central portions of the CONUS Thursday.
This quickly developing system will draw down much colder Canadian
air into the northern Plains and through the Midwest. Will
probably see more light precip as the front pushes through...with
some light accumulating snow possible in the northern Black Hills.
At this point it looks like the area could see temps down into
the teens/low 20s for the first time this season. Then end of the
week looks warmer again as strong ridging is reinforced across the
western half of the CONUS.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1107 AM MDT Sun Oct 22 2017

VFR conditions expected through the period. Gusty west/southwest
winds will occur over northeast WY through early this evening. A
cold front will move through the area tonight bringing gusty
northwest winds and scattered SHRA. Some low level wind shear may
occur ahead of the front.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Watch from Monday morning through Monday evening for
     SDZ001-002-012>014-025-026-031-032-072-073.

WY...High Wind Watch from Monday morning through Monday evening for
     WYZ071.

&&

$$

DISCUSSION...13
AVIATION...Johnson



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