Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 111711 AAB

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1111 AM CST Wed Jan 11 2017

Issued at 1106 AM CST Wed Jan 11 2017

Updated the forecast this morning to cancel the wind chill
advisory. None of the current or past observations reached wind
chill advisory criteria. Have also removed the mention of snow
sooner than the previous forecast indicated.

UPDATE Issued at 534 AM CST Wed Jan 11 2017

See below for an aviation forecast discussion for the 12Z TAFs.


.SHORT TERM...(Today through Friday Afternoon)
Issued at 346 AM CST Wed Jan 11 2017

Snow slowly ending (or at least sinking south), with cold
overspreading the area. Expect falling temperatures during the day
today. The result will even be a few reports of wind chill
readings near -25F from 12Z- 18Z. The area of concern would mainly
be the northern tier counties from Corson through Day and Roberts
Counties. Issued a Wind Chill Advisory for this area.

A 500mb trough to zonal flow will remain across the region through
the end of the work week. The sfc trough over NE extending up
through southeastern SD early this morning will continue to lose
control of the region as the strong high sinks in from the
northwest. Expect the sfc high to be overhead this afternoon through
06Z Thursday. At that point, a trough extending from a low crossing
southern Manitoba will moving across at least our northeastern area.
The main impact will be to reinforce the cold air. Thursday morning
will have a llj of around 30kts at 925mb. Did increase sfc winds
slightly, but with a pretty strong inversion in place, not sure how
much of these winds will make it to the sfc. The best chance of 20-
30kt winds will be over/east of the Sisseton Hills from around
daybreak through mid afternoon Thursday. Included the mention of
blowing snow in the fcst, and the potential for significant blowing
snow on breezy to strong winds in the HWO. Also included the mention
of wind chill values again briefly dip to or below Advisory
criteria over northern/northeastern areas.

Expect another, stronger 1040mb sfc high to move from southern
Saskatchewan/eastern MT Thursday morning to the eastern Dakotas
Thursday night. Light winds and very cold air will result. Expect
temperatures Thursday night to fall into the -5 to -25F range, with
the lowest readings over and east of the James River Valley.
Continued to drop temperatures a few degrees below the statistical
consensus solution. These temperatures, combined with increasing
westerly winds will result in wind chill values of -20 to near -40F.
Will likely need Wind Chill Advisories and Warnings for much of the
James River Valley and east. As we move into the daytime hours, the
very strong sfc high will exit across MN/WI. Expect winds to be on
the increase Friday afternoon, and may need to be increased more
than the ongoing fcst.

.LONG TERM...(Friday Evening through Tuesday)
Issued at 346 AM CST Wed Jan 11 2017

Almost all of the extended forecast is a dry forecast. The period is
also progged to be notably warmer than the recent past has been.
Still worth mentioning is the large synoptic scale low pressure
system that deepens and takes aim on the mid to deep South by early
next week. Once the system occludes, models are continuing a trend
of drawing its decaying/weakening upper circulation northeastward.
00Z solutions basically keep any precip with this circulation south
and/or east of this cwa, but superblend nudged some very low slt
chance pops into the southeastern third of the cwa for a short
period of time. Will continue to monitor model trends of track and
timing of this weakening upper circulation.


.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 534 AM CST Wed Jan 11 2017

There`s more snow falling across the forecast area this morning.
But, basically, cigs are about as low as they are going to get
(generally 2500ft to 4500ft agl). It`s the visibility obscuration
in light to occasionally moderate snowfall that is expected to
hold in the MVFR to occasionally IFR range this morning. By mid-
day, the snow should be ended at all four terminals, and some
rather cold VFR conditions will be ensuing for the rest of the 24
hour TAF valid period. The lone exception is at KPIR when, later
tonight for perhaps a few hours, the next low pressure system
moves through, generating some light snow across the far southern
portions of South Dakota.




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