Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 091139 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
539 AM CST Fri Dec 9 2016

.SHORT TERM...(Today through Sunday Afternoon)
Issued at 353 AM CST Fri Dec 9 2016

Still a massive blob of lake-effect stratus across the southwest
CWA. Have watched this all night and has actually begun to spread
back to the southwest as the fetch off Lake Oahe has turned
clockwise with the surface wind flow as the high pressure moves on
through. These clouds have kept temperatures up a bit, but further
north, still clear skies where readings have dipped into the teens
below zero over Corson and Dewey counties. Wind chills not a problem
as winds are light and variable under the high, so no headlines
needed this morning even though they are issued to areas north and
west. Plus, stratus deck moving northeast out of UNR CWA ready to
head into north central SD, so may actually see rising temps through
sunrise. There have been a few flurries at times as well within the
stratus decks and have included that in the grids.

Otherwise for today, will be watching weak warm air advection-
induced light snow across southern SD. Some of this activity may
spread into the southern CWA with light snow accums and have
increased POPs a bit into the chance category. Profiles moisten up
quite a bit actually, as some weak lift also is generated within the
DGZ. Already starting to see light snow move into southwest SD so it
appears this minor event is panning out and may need to increase
POPs to likely before too long. But again, snow accums will be very
light and only amount to around a half inch or so.

Main story in the short term is the stronger surface trough that
moves across the Plains Saturday and Sunday. Models beginning to
come to better agreement in the evolution of the system and QPF
placement. Strong warm air advection pattern develops tonight and
into the day Saturday, with moisture increasing as well. Good
amounts of forcing as well as the inverted surface trough slowly
moves across the region. Energy aloft begins to swing east across
the Dakotas Saturday night into Sunday. Models have started a trend
of lingering snow over the eastern CWA longer through the morning
Sunday as weak lift remains in place as the surface trough and warm
air advection pattern persist. In general, it appears a solid 2 to 4
inches are becoming likely across most of the CWA east of the
Missouri River, with the highest amounts across the eastern CWA. It
still appears winds will not be a big factor with this system and
should generally stay in the 10 to 20 mph range. Day shift may need
to consider an advisory due mainly to the snowfall amounts as there
should not be any noteworthy impacts from blowing snow.

.LONG TERM...(Sunday Evening through Thursday)
Issued at 353 AM CST Fri Dec 9 2016

An upper low will dig down from Canada starting Monday night. With
sfc high pressure also in place, it looks like even colder temps are
in store for the region. As the arctic front pushes in on Monday it
will squeeze out any remaining moisture and produce flurries and
snow showers. Gusty winds will also mix down. Bumped up winds quite
a bit from Blender Monday/Mon night with a nudge toward MOSGuide.
Tuesday and Wednesday are expected to be cold and dry with highs in
the single digits, but some lingering clouds may ameliorate the deep

Long range models are indicating the potential for some late week
snow. At this time range a lot of uncertainty remains, and it is
definitely possible the system may track a bit farther south as
another arctic high moves in from the northwest.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 532 AM CST Fri Dec 9 2016

A persistent area of MVFR/IFR stratus will continue to affect
sites along the Missouri River. Light snow, associated with some
short wave energy, will move across central SD today. While KATY
is not expected to see much in the way of precip today, MVFR cigs
will move in this afternoon.




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