Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 172146
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
246 PM MST Fri Nov 17 2017

.DISCUSSION...(This Evening Through Friday)
Issued at 246 PM MST Fri Nov 17 2017

Current surface analysis shows initial cold front south of the
forecast area, with a secondary front edging into northern SD.
Upper level analysis shows fast zonal flow across the area, with a
trough moving quickly east-southeast across the central Rockies.
Jet energy ahead of the trough is helping to produce areas of pcpn
across the forecast area. Pcpn is in the form of light rain
across the SD plains, with mostly light snow or flurries across
northeast WY and the Black Hills. Temps across the forecast area
range from the mid 30s over northeast WY and the higher Black
Hills to the upper 40s over south central SD. Winds are variable
at 10 mph or less in most areas.

Light rain and snow will linger into the evening over most of the
area, before ending overnight. Little or no accumulation is expected
in most areas, possibly an inch or so over the Black Hills. North-
northwest winds will become breezy in many areas tonight as area of
low pressure passes southeast of the region and secondary front
passes through at least northern and eastern portions of the
area. Brisk winds will continue into Saturday, especially across
the SD plains.

A mainly dry pattern is setting up for the next week as west-
northwest flow aloft persists across the region. The weekend will
start off on the cool side with highs on Saturday in the mid 30s to
mid 40s. Warmer air will return for Sunday and Monday as a ridge
slides across the region. Temps will be 10 to 20 degrees above
average Monday, ahead of the next cold front that will pass through
Monday night. The front looks to be dry as main shortwave energy is
progged to pass southwest of the forecast area. Temperatures on
Tuesday will be back down to near average levels.

Ridge will rebuild over the Rockies midweek, bringing milder air
back to the area. The outlook for Wednesday through Friday is still
mild and dry, with forecast highs in the 60s for some areas on
Thanksgiving day.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1033 AM MST Fri Nov 17 2017

MVFR and IFR conditions are expected across much of the area
today as rain and snow crosses northeast Wyoming and western
South Dakota. IFR conditions are likely across the Black Hills
area as snow falls over the area. Conditions will improve to VFR
tonight as drier air moves in.

&&

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

$$

DISCUSSION...26
AVIATION...15



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