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000
FXUS63 KABR 171640
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1040 AM CST Fri Jan 17 2020

.UPDATE...
Issued at 1040 AM CST Fri Jan 17 2020

Slowed down the exit of snow by 3-6 hours, and increased
precipitation/snow amounts for late this evening on as another
push of snow moves into the area. CAM solutions have been hinting
as the slower exit this morning, and it looks reasonable. The main
result is slightly higher snow amounts of around 1 to near 2in
for areas east of the Missouri River, as well as Lyman County.
Headlines still look good for now. Will need to monitor
precipitation amounts for our southwestern counties, to see if
anything but High Wind Warnings will be needed. If significant
snow falls, they will need to be included in a Winter Weather
Advisory this evening, or Blizzard Warning overnight.

&&

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 356 AM CST Fri Jan 17 2020

A complex storm system will impact the region over the next 36
hours. Strong south to southeasterly winds this morning is producing
areas of blowing and drifting snow with visibility at KABR down to
one mile at times. Visibility at other observation points are
between 3 to 6SM. Various webcams also show blowing snow, but not
whiteout conditions, even with sustained winds above 30 mph. Winds
are expected to slowly weaken today in the eastern CWA as
accumulating snow moves in. With the strong warm air advection,
along with LLM, there could be a brief period of freezing drizzle
and sleet before transitioning over to all snow. Hi-res models
show a very small window of mixed pcpn. Ensemble viewer from WPC
also indicates very little to no ice today. Winter weather
headlines for the today period is very problematic in the eastern
CWA. The southeasterly winds, along with falling snow could cause
near whiteout conditions. Will maintain the current winter storm
warning for now and allow the day shift to upgrade as needed.
Snowfall amounts, if one is able to measure with the winds, should
range from 1 to 3 inches in the James Valley, to four inches or
more east of I-29. Of note, models have shifted slightly westward
with light, accumulating snowfall.

Headlines tonight through Saturday are slightly less problematic.
The combination of strong cold air advection and 6-hour pressure
rises of 10 to 15 mb will bring powerful winds to the CWA tonight
through Saturday. Will issue a high wind warning for tonight for
counties west of the Missouri River, and a few counties to the
east where little snowfall is expected today. If more snow falls
in the Pierre area tonight, then a blizzard warning will be
needed. Elsewhere, fresh snowfall of an inch to 4 inches, along
with wind gusts of 50 mph will cause blizzard conditions. The SREF
probability of blizzard conditions met still highlights a portion
of eastern South Dakota late tonight into the morning hours on
Saturday.

.LONG TERM...(Saturday Evening through Thursday)
Issued at 356 AM CST Fri Jan 17 2020

Overall, the long term looks relatively tranquil, until perhaps
toward the end of the period. A somewhat progressive mid-level flow
pattern continues across the CONUS, but does slow up to some degree.
A ridge aloft builds into the region for Sunday through about
Tuesday, with generally dry conditions expected during that period.
The ridge pushes off to the east by Thursday and Friday as a trof
aloft advects into the middle of the CONUS. There are some
differences in the speed/orientation/latitude of this system, and
thus forecaster confidence in the details is somewhat low at this
time. In house model blend will do fine for now. That said the
deterministic GFS/CMC are fairly aggressive with a storm across the
Central and perhaps even Northern Plains Thursday and Friday. The
ECMWF is somewhat muted in comparison. Need more time to nail down
the details with this potential storm. Temperatures will start the
period cold, but then should trend toward or even above normal as
the ridge builds over the region for the middle of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1040 AM CST Fri Jan 17 2020

Winds continue to gusts 30 to 40kts, with winds at MBG/PIR
diminishing after 20Z as the surface low nears from western SD.
This brief period of lighter winds moving west to east across the
TAF sites will quickly increase again behind the front and become
out of the northwest with gusts nearing 40-50kts at MBG/PIR by
03Z, ABR by 06Z, and ATY by around 08Z Saturday. Light snow and
freezing drizzle have been reported across the area, at the onset
of the precipitation. Expect snow to become the dominant weather
type during the afternoon hours. MVFR to IFR ceilings/vis will
dominate, with lower conditions in moderate snow and strong
winds/blowing snow.


As a system moves closer to the region, IFR cigs
are expected to advect across the area this morning. Vsbys will
also lower to MVFR/IFR over the eastern part of South Dakota as
the snow moves into the region this morning.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 9 PM CST this evening for
     SDZ004>006-009-010-017-018-036-037-051.

     Blizzard Warning from 9 PM this evening to 3 PM CST Saturday for
     SDZ004-005-009-010-017-036-037-051.

     Winter Storm Warning until midnight CST tonight for SDZ007-008-
     011-019>023.

     Blizzard Warning from midnight tonight to 6 PM CST Saturday for
     SDZ007-008-011-019>023.

     High Wind Warning from 6 PM CST /5 PM MST/ this evening to 6 AM
     CST /5 AM MST/ Saturday for SDZ003-015-016-033>035-045-048.

     Blizzard Warning from 9 PM this evening to 6 PM CST Saturday for
     SDZ006-018.

     Winter Weather Advisory until 6 PM CST this evening for SDZ048.

MN...Winter Storm Warning until 3 AM CST Saturday for MNZ039-046.

     Blizzard Warning from 3 AM to 6 PM CST Saturday for MNZ039-046.

&&

$$

UPDATE...KF
SHORT TERM...SD
LONG TERM...TDK
AVIATION...KF