Area Forecast Discussion
Issued by NWS Aberdeen, SD

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619
FXUS63 KABR 211129 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
529 AM CST Sun Jan 21 2018

.UPDATE...
Issued at 524 AM CST Sun Jan 21 2018

12z aviation discussion updated below.

&&

.SHORT TERM...(Today through Monday Afternoon)
Issued at 338 AM CST Sun Jan 21 2018

Models are coming into a better agreement with a winter storm
impacting south central and southeastern SD today through Monday.

As of 9Z, an upper level trough of low pressure is located over the
four corners region. Moisture advection, along with a 100+ knot
upper level jet ahead of the trough is producing snow over
southwestern SD this morning. While pcpn is moving east-northeast,
it is running into drier air in the lower level with little pcpn
so far in this CWA. KPIR, along with webcams south of Pierre have
reported light rain. Accumulating snow is not far away as a webcam
in Belvidere or west of Murdo is showing snow. Cams generally
suggest this west/east of pcpn will fill in south of highway 212
today. Snowfall amounts of a half inch, to two inches will be
possible within this narrow band of pcpn. Higher amounts are
expected along and south of Interstate 90 through this evening.
While models have backed off on snowfall amounts in Jones and
Lyman County, will maintain the current winter storm warning. With
less snow expected in Buffalo County, will issue an advisory for
the possibility of 2 to 3 inches.

Snowfall amounts tonight through Monday in our southeastern portion
of the CWA is a little more unclear. The past few runs of the ECAM,
plus other hi-res models keeps our southeast dry with no snow in
Watertown, and very little snow in Clear Lake. GSM are a little more
robust with QPF and thus mentions accumulating snow for Watertown
and Clear Lake. Based on SREF plumes, will mention pcpn in our
southeast, including the potential for 2 to 4 inches in Deuel
County. With northerly winds of 20 to 30 mph with higher gusts,
patchy blowing snow will be possible for a portion of I-29 Monday
morning. This storm system should be east of the our CWA by Monday
afternoon.

.LONG TERM...(Monday Evening through Saturday)
Issued at 338 AM CST Sun Jan 21 2018

A weak upper level shortwave will track across the region Tuesday
morning, however time-heights show moisture is lacking so this
system likely will move through dry, with cloud cover the only
result. An upper level ridge/WAA pattern is then expected for the
remainder of the workweek. High temperatures throughout the week
will range from 10 to 20 degrees above normal for this time of the
year.

Will see the pattern shift to southwest flow aloft as a long wave
through moves over the western CONUS by the weekend. Sometime in
the Friday/Saturday time period models are suggesting a low pressure
system develops out of the Rockies, bringing precipitation chances
back to the region. Too soon to really dig into the details, but
there could be a rain snow mix before precip turns to all snow with
this system. Current model 850 MB temperatures range from the single
digits above zero Friday morning ahead of the front, dropping to the
teens below zero behind the front Saturday morning.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 524 AM CST Sun Jan 21 2018

VFR conditions are expected at KMBG through the period. A storm
system passing south of the region could spread light snow to the
terminals of KPIR and KATY today through tonight. If snow reaches
these terminals then MVFR conditions will be possible. Otherwise,
KATY and KABR could see lower cigs later tonight with IFR to MVFR
conditions possible.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning until 6 AM CST Monday for SDZ045-048.

     Winter Weather Advisory until 6 AM CST Monday for SDZ051.

     Winter Weather Advisory until 6 AM CST /5 AM MST/ Monday for
     SDZ033-035.

     Winter Weather Advisory from 6 PM this evening to 6 PM CST
     Monday for SDZ023.

MN...None.
&&

$$

UPDATE...SD
SHORT TERM...SD
LONG TERM...Serr
AVIATION...SD



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