Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 171741 AAD

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1141 AM CST Sun Dec 17 2017

Issued at 953 AM CST Sun Dec 17 2017

No significant changes to the forecast this morning. Two layers
of clouds across the area with high clouds pushing east ahead of
an approaching shortwave entering wrn SD and MVFR/VFR clouds over
the southwestern half to two thirds of SD. The lower clouds will
be slow to move through the rest of the morning, but should start
to slide east and slowly dissipate through the afternoon and
evening as WSW flow increases.

UPDATE Issued at 711 AM CST Sun Dec 17 2017

Visibilities have begun to improve across the northeastern CWA,
therefore the Dense Fog Advisory has been cancelled.


.SHORT TERM...(Today and Tonight)
Issued at 300 AM CST Sun Dec 17 2017

Dry with light winds and above normal temperatures will describe
this period. Other than the morning fog, the main weather of
interest will be cloud cover and fog. Areas of dense fog over
eastern SD and western MN continue. The coverage is not
continuous, but low enough to hoist a dense fog advisory for
the morning hours, as the fog should linger trough mid
morning before dissipating or exiting east.

Will be stuck with plenty of clouds today, that will slide southeast
as the day goes on as the 500mb trough stretching from Manitoba
through eastern MT/WY and down through northwestern Mexico slides
east. This feature will be over eastern ND and western SD by mid
day, with clouds beginning to exit east as the trough to our
eastern counties by 00Z Monday, and to our southeast by 03Z. The
clear sky will not last long, as high clouds invade from the
northwest tonight.

.LONG TERM...(Monday through Saturday)
Issued at 300 AM CST Sun Dec 17 2017

Upper level northwest flow will be dominant over the area Monday
through the day Wednesday. A fairly strong shortwave trough then
approaches and looks to track across the central part of the country
Wednesday night into Thursday, with a very broad trough then
developing and encompassing much of the CONUS over the weekend.

At the surface, a dry frontal boundary will track across the area on
Monday, followed by a period of high pressure on Tuesday. Attention
then turns to an approaching low pressure system that looks to bring
the next chance of precipitation. The low and associated frontal
boundary will track across the CWA Wednesday afternoon and evening,
with post frontal precipitation developing on Thursday. This is
about 12 hours slower than yesterday morning`s model runs, which had
sped things up from the runs previous to that. This yo-yo pattern
will have to continue to be monitored closely. For now, it appears
the best chance for snow will be late Wednesday night into Thursday,
with some lingering light snow across the southeast Thursday night.
The ECMWF and Canadian models are currently the most aggressive with
snow amounts, with the GFS indicating lesser amounts. A decent
pressure gradient develops as well, with this event still looking
like it could end up being a low snow amount/high wind event. The
latter half of the period will remain unsettled, with periods of
light snow possible under the broad upper trough.

Mild temperatures will continue into the first half of the long term
period, with highs in the 40s and 50s on Monday, and in the 30s and
40s Tuesday and Wednesday. Will then see a big downward turn in
temperatures, with highs mainly in the teens Thursday, Friday and


.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 1140 AM CST Sun Dec 17 2017

Expect VFR conditions to occur through the period. Still some
lingering low end VFR ceilings along the KPIR to KATY line that
are pushing east, but expect them to slowly raise and largely be
south of the TAF sites.  Otherwise, the mid clouds over the area
should depart from west to east this afternoon into evening
before high clouds approach late tonight into Monday. Winds will
become gusty late in the period and expect the strongest winds of
around 25kts near KMBG to occur after the TAF valid period.




LONG TERM...Parkin
AVIATION...SRF is the U.S. government's official web portal to all federal, state and local government web resources and services.