Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 191147

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
447 AM MST Fri Jan 19 2018

.DISCUSSION...(Today Through Thursday)
Issued at 315 AM MST Fri Jan 19 2018

Current surface shows weak cold front across eastern Montana into
northern Wyoming. Gusty west-southwest winds across northeast
Wyoming and Black Hills keeping temperatures up in the 50s. Low
level thermal ridge shifts east today as weak cold front slides
through forecast area.

Upper trof moving into western CONUS slides through the Rockies on
Saturday, with cut off low developing over the four corners
region...then lifting through the central plains. Forecast area
will be in right entrance region of jet from Dakotas into the
Great Lakes region. Enhanced frontogenisis along baroclinic zone
will bring band of snow from east central Wyoming into southwest
South Dakota/northwest Nebraska Saturday afternoon through
Saturday night. Latest guidance shifting best lift slightly
southward with axis of heaviest snow along Nebraska border...along
with sharp cutoff on northern edge of snow. As upper low moves
through the central plains into Iowa Sunday night, South central
South Dakota will be near northern edge of TROWAL. Increasing
winds should result in some blowing snow across south central
South Dakota. With the southward shift, have decreased snowfall
amounts along the I-90 corridor including the Rapid City area.
Issued winter storm watch along the Nebraska border starting
Saturday afternoon in the far southwest and ending in south
central zones Sunday evening.

Near average temperatures expected for next week. Next chance of
widespread precipitation will come near the end of the week.


.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 447 AM MST Fri Jan 19 2018

VFR conditions will continue across the area today. Gusty west-
southwest winds over parts of northeast WY and the Black Hills
will diminish by late this morning. Areas of MVFR conditions will
spread into northeast WY later tonight and western SD by early
Saturday as a storm system approaches. Chances for light snow will
also develop across northeast WY into parts of western SD late
tonight/early Saturday.


SD...Winter Storm Watch from Saturday evening through Sunday evening
     for SDZ042>044-046-047-049.

     Winter Storm Watch from Saturday afternoon through Sunday
     morning for SDZ027-029-041.



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