810 
FXUS63 KUNR 141727
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1027 AM MST Sat Dec 14 2019

.UPDATE...
Issued at 614 AM MST Sat Dec 14 2019

Moist easterly upslope flow has lead to the development of fairly
widespread freezing fog on the plains around the Black Hills. 
Decided to issue an advisory until 11 am given poor visibility and
potential icy roads from frost. 

&&

.DISCUSSION...(Today Through Friday)
Issued at 108 AM MST Sat Dec 14 2019

Active split flow will persist into early next week with NW flow 
continuing locally. Arctic front has backed into the region and 
stalled and will remain over the FA through the weekend. The next
impulse will push into the region today, supporting a weak FGEN 
response across the SW third of the FA. Light snow can be 
expected to develop this afternoon and persist into the evening,
mainly over SW areas. Generally 1 to 2 inches are forecast there,
with locally 2-3 inches over southern Fall River and Oglala 
Lakota counties. The region will remain on the edge of the mean 
NOAM trough through early next week as several impulses rotate 
through the base of the trough into the upper Midwest, anchoring 
the front over the Northern Plains. Bulk of forcing will remain 
well north of the area supporting dry conds after today. Warm 
downslope Pac air will push into the region by mid next week, with
mild conds looking on track by then. Current forecast model 
trends are for mild and dry conds to persist into next weekend. 

&&

.AVIATION...(For the 18Z TAFS Through 18Z Sunday)
Issued At 1025 AM MST Sat Dec 14 2019

Widespread MVFR/IFR conditions will continue today and tonight. 
Weak upslope flow will keep some LIFR freezing fog around the 
Black Hills into early afternoon. Light snow will move in this 
afternoon...with the snow gradually shift out of the area early 
Sunday morning.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Freezing Fog Advisory until 11 AM MST this morning for SDZ012-
     025>027-030-031-041-072>074.

WY...Freezing Fog Advisory until 11 AM MST this morning for WYZ057-
     058-071.

&&

$$

Update...JC
DISCUSSION...JC
AVIATION...7