Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 121125 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
525 AM CST Tue Dec 12 2017

.SHORT TERM...(Today and Tonight)
Issued at 359 AM CST Tue Dec 12 2017

The ridge of high pressure at the sfc is exiting to our south early
this morning, with our attention moving to the wave moving across
British Columbia. While the overall 500mb pattern of 500mb trough
east, and ride over the far western states remains, this trough will
sink across southern Saskatchewan early this evening, and and over
the eastern Dakotas overnight. Taking a look at the sfc pattern,
warmer air looks to be the rule today. Expect highs in the 50s to
near 60F west to the upper 30s east as a weak trough slowly pushing
into the Dakotas. This will be in advance of the sfc low that will
be set up across southern Manitoba by 00z Wednesday. Temperatures
will be tricky tonight, hovering near freezing, with the potential
to be a few degrees above freezing for much of the night. Road
surfaces may be cooler, leading to an issue of light mixed
precipitation that could accumulate across frozen surfaces. Any
precipitation that does fall prior to 12Z Wednesday should be light.
The main change is an increase to the winds tonight as the sfc low
shifts into MN after 06Z. Windy conditions will be the rule with
winds out of the northwest gusting 35 to near 45 mph, especially
over and west of the James River Valley. Included the mention of
light icing, and increasing winds in the HWO.

.LONG TERM...(Wednesday night through Monday)
Issued at 359 AM CST Tue Dec 12 2017

The highly meridional pattern across the conus is expected to
continue, but with some modification. The latest models are hinting
at de-amplification, along with a retrogression of the long wave over
the continent. These changes could eventually lead to a cooler
forecast overall, but that isn`t likely to occur until a week or so
from now.

The main systems to affect the forecast area during the period will
be on Wednesday, Thursday, and some weaker energy for the weekend.
Each system looks to provide at best only light amounts of pcpn. The
Wednesday system may have the potential to produce a mix of types,
at least early on Wednesday.  However, confidence in ll thermal
progs is low and we might end up being warmer than currently
forecast as mixing a head of southeastward moving clipper will be
good. This will mean the difference between rain/snow and some
freezing rain. That said most of the pcpn on Wednesday is expected
over the northeast cwa, and mainly in the morning.

The system for Thursday should deliver mostly snow as critical
thickness and soundings point to that pcpn type being predominant.
Once again pcpn amounts are expected to be light. Temperatures
overall will favor near to above normal for the period as the area
continues to bask under a relatively mild airmass.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 522 AM CST Tue Dec 12 2017

A batch of mvfr cigs over KABR/KATY will gradually dissipate this
morning, leaving VFR conditions region-wide for the rest of the
day. Gusty winds will invade the area late tonight.




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