Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 141744

Area Forecast Discussion
National Weather Service Aberdeen SD
1144 AM CST Wed Feb 14 2018

Issued at 1130 AM CST Wed Feb 14 2018

No changes foreseeable today. Focus will be on return of Arctic
air into South Dakota early Thursday morning with some light snow
in its wake, mainly across western/central South Dakota around mid
day Thursday.


.SHORT TERM...(Today and Tonight)
Issued at 335 AM CST Wed Feb 14 2018

High temperatures today will be the main challenge in the short
term. As the previous discussion noted, there is a fair amount of
snow cover from KPIR to KHON, and to the Watertown area.
Northeastern South Dakota and western Minnesota has much less snow
depth per NOHRSC and visible satellite. Complicating matters, model
soundings are showing a bit of an inversion to overcome today and
low level mixing winds may not be as significant as expected. The
GFS and NAM are more pessimistic with temperatures showing highs in
the upper 30s and lower 40s for most locations. The past few hourly
runs of the ECAM and the 0Z ECMWF are much warmer today, especially
in northeast SD and western MN. These models are showing highs
reaching the mid to upper 40s over the less snow covered areas. With
low forecaster confidence, have made minor changes to high
temperatures today. Tonight will feature increasing cloud cover
with low temperatures in the teens and low 20s.

.LONG TERM...(Thursday through Tuesday)
Issued at 335 AM CST Wed Feb 14 2018

Thursday is still on track for some light snow to develop as an
Arctic boundary moves southward along with lift from an upper level
low pressure trough coming in from the northwest. The lift with this
system will be weak bringing snowfall amounts of an inch or less.
With the surface pressure gradient tightening up along with caa,
increased winds on Thursday into the 15 to 30 mph range. Otherwise,
a surface high pressure area will slide southeast across the region
Thursday night. The additional light snow along with clearing skies
on Thursday night will bring below zero temperatures. If winds fall
off more and better decoupling occurs, temperatures could be even
lower. Temperatures will warm a little from Friday through Sunday
before the next Arctic boundary moves in with much colder
temperatures for Monday and Tuesday. Friday through Sunday should
still be near to around 5 degrees below normal with much below
normal temperatures for both Monday and Tuesday. A weak short trough
and surface trough/cold front will pass through the region later
Friday night and Saturday bringing small chances of light snow
southwest in the cwa at this time.

The models then show the upper level flow transitioning from
northwest to southwest flow from Saturday into Monday as low
pressure troughing develops over the western U.S. At this time, the
models all vary on the strength and location of this trough with the
EC the strongest. Therefore, the consensus is for chances of light
snow from Sunday into Tuesday as warm air overruns the Arctic
boundary along several short waves coming off the western upper


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1130 AM CST Wed Feb 14 2018

Winds are mainly west to south, but will become northerly after a
front passes through the area Thursday. VFR conditions are
expected otherwise, until passage of the front, which will
introduce lower CIGS and VISBY reductions due to snow for mainly




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