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Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
817 PM MST Thu Dec 5 2019

issued at 808 PM MST Thu Dec 5 2019

Cold front has pushed through the forecast area with high
pressure moving southward into the northern plains. Post-frontal
stratus has developed across most of the area with fog/freezing
fog where northeast upslope winds have pushed the cold airmass
against the Black Hills. The clouds and fog will persist through
the night, with skies clearing Friday morning as Lee trof deepens
over eastern Mt-WY.


Discussion...Friday through Thursday
issued at 117 PM MST Thu Dec 5 2019

Relatively quiet weather Friday as robust warm air advection
returns to the region Friday. Large scale ridging behind departing
southern stream trough and a deep trough off the Pacific northwest coast
will yield a warm and pleasant day Saturday. Highs across much of
western South Dakota and northeastern Wyoming will push into the upper 40s to
low 50s.

Another cold front will crash southward late Sunday into Monday and
bring much colder temperatures to the region. Much of the
forecast area will likely see light snow with minor accumulations
Sunday night into Monday. While the coldest air will remain to
our north and east, the frontal zone will largely stay stationary
for much of next week with cooler than normal temperatures. There
is considerable uncertainty surrounding temperatures late next
week. While the ensemble spread is large, the overall pattern
would support relatively cool and unsettled weather.


Aviation...for the 00z tafs through 00z Friday evening
issued at 430 PM MST Thu Dec 5 2019

High pressure is moving into the northern plains behind cold
front, which is now west of forecast area. IFR cigs/vsby will
expand with areas of freezing fog and LIFR conditions, especially
around the Black Hills. Conditions will improve Friday morning as
winds shift to the southwest.


Unr watches/warnings/advisories...
South Dakota...none.

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