Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 231150 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
550 AM CST Mon Jan 23 2017

Issued at 549 AM CST Mon Jan 23 2017

12z aviation discussion updated below.


.SHORT TERM...(Today through Wednesday afternoon)
Issued at 407 AM CST Mon Jan 23 2017

A storm system impacting the region through the short term will
produce a challenging forecast.

While it may not seem like it, there is significant moisture over
the central Rockies where derived satellite imagery shows total
blended PWATS of 200 percent of normal. Some of this moisture will
lift northeast from Wyoming into north central SD by this afternoon.
This moisture, along with easterly upslope flow and isentropic lift
will likely result in accumulating snowfall in north central SD. The
0Z NAM was showing heavy snowfall in Corson and Dewey Co from 21Z
Mon to 0Z Wednesday. The 6Z NAM has backed off some, but still shows
a few inches of snow starting by 0Z Tuesday. Overall, high end
advisory level snowfall will be possible in north central SD with
this system.

Heavier snowfall, in excess of 4 plus inches is likely along and
south of Highway 14, including I-90 corridor. This is where models
shows the best LLM and upper level lift. Decent instability may
result in more than one band of heavy snowfall. With the ECMWF and
Canadian a bit further south, will maintain the current winter
storm watch. As the surface low begins to exit the region Tuesday
night into Wednesday, increasing northerly winds could cause some
blowing snow issues.

.LONG TERM...(Wednesday evening through Sunday)
Issued at 407 AM CST Mon Jan 23 2017

The models agree well and have been consistent in the long term with
a west coast upper level ridge building slowly east through the
period. At the surface, high pressure will cover much of the western
U.S. bringing prevailing northwest winds at the surface across our
CWA through most of the period. The Canadian air being advected in
will not be overly cold. Although, the new layer of snow on the
ground will have an affect on the temperatures. At this time,
temperatures in the upper teens and lower 20s on Thursday are
expected to rise to the upper 20s to the mid 30s by Sunday. After a
few lingering light snow showers across the far east Wednesday
night, the rest of the long term looks to be dry across the CWA.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 549 AM CST Mon Jan 23 2017

IFR/MVFR stratus ceilings will remain over all locations through
today and tonight. A surface low pressure system moving in from the
west will spread snow across the region through tonight affecting
all locations with visibilities down to a mile at times.


SD...Winter Storm Watch from late tonight through late Tuesday night
     for SDZ033>037-045-048-051.



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