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FXUS63 KUNR 172104
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
204 PM MST Sat Nov 17 2018

.DISCUSSION...(This Evening Through Saturday)
Issued at 203 PM MST Sat Nov 17 2018

21z surface analysis had high pressure over eastern SD. Water
vapour matinee had upper trough from central Canada into WY,
moving eastward. Satellite showed extensive stratus had eroded
over the higher Black Hills and was starting to erode over
northwest SD.

Tonight, drier air moves into the area slowly scouring the
stratus. Temperatures will be very tricky with warm air advection
on back side of high battling radiational cooling. Went on cool
side of guidance, especially in the southwest where light
snowcover will be present when skies clear.

Sunday, shortwave trough zips across central Canada into the upper
Midwest as upper ridge builds over the western CONUS. Low level
warm air advection continues. A bit of snow may occur later in
the day into the night, possibly starting off as rain. Little
accumulation expected. Temperatures will be near guidance.

Monday through Thanksgiving Day, CONUS upper ridge will dominate
with thermal ridge over the CWA and above normal temperatures.
Lovely weather expected for initial holiday travel.

Friday into next weekend, progressive flow develops with passing
troughs/cold fronts and a return to seasonal temperatures.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Sunday)
Issued At 1026 AM MST Sat Nov 17 2018

Widespread MVFR/IFR conditions will continue through this
afternoon as stratus deck and some light snow linger. Gradual
improvement to VFR is expected over northeast Wyoming later this
afternoon as drier air moves in from the northwest. Improvement to
VFR by this evening across western SD. VFR conditions are then
expected into Sunday morning.

&&

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

$$

DISCUSSION...Helgeson
AVIATION...15
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