Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 171723

Area Forecast Discussion
National Weather Service Aberdeen SD
1123 AM CST Sat Feb 17 2018

Issued at 1123 AM CST Sat Feb 17 2018

Spend up the exit of the light snow over our southern counties
this morning. While it was able to reduce visibilities of around
1.5mi at times, accumulations were minimal. PIR and HON reported
just a trace to 0.01in of liquid. Will now look for snow and
freezing drizzle to near the ND/SD border overnight and into
Sunday morning.


.SHORT TERM...(Today through Sunday Afternoon)
Issued at 336 AM CST Sat Feb 17 2018

A weak low pressure system and broad upper level trough will cross
the region this morning. This system will bring light snow, mainly
to central and south central SD. Models have really backed off on
the amount of moisture associated with this wave with snowfall
amounts of a dusting to a half inch expected. Models are even faster
with pcpn ending in this CWA between 18-21Z.

A stronger low pressure system will cross South Dakota later tonight
through Sunday. This system will bring accumulating snow to North
Dakota and perhaps along and north of Highway 12 in South Dakota.
The ECMWF and NAM are the furthest north solutions with little snow
expected in our CWA. The 6Z NAM is even further north with the pcpn.
The GFS and Canadian model are a bit further south with 1 to 2
inches of snow possible along the ND/SD border. An in-house blend
of models yields high pops north of Highway 12, but with snowfall
amounts under an inch. Models soundings still support the
possibility of freezing drizzle with minor ice accumulations

.LONG TERM...(Sunday Evening through Friday)
Issued at 336 AM CST Sat Feb 17 2018

The latest models continue to advertise the development of a
positive tilt mid level trof over the western conus, extending
northeast into the Western High Plains. A mean sfc front will extend
from Colorado east/ne into Iowa. The models maintain some form of
baroclinic zone across South Dakota from Sunday night through Monday
night. A band of snow/pcpn Sunday night is depicted similarly among
the models.  However, differences begin to take shape for Monday
through Monday night. There is only partial agreement on where
follow on snow bands will set up, thus forecast confidence in snow
amounts and placement are fair at best for now. Hopefully future
runs will show the models converging rather than diverging. One
thing looks for sure, snow ratios will be quite high for Sunday
night through Monday night given influx of arctic air. The rest of
the period looks pretty much dry. Temperatures look to favor below
normal until toward the end of the next work week.


.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1123 AM CST Sat Feb 17 2018

VFR ceilings and vis anticipated at all terminals. The main
concern will be the wind sheer starting 06-11Z, and continuing
through much of the forecast period. Stronger winds just above
the surface will be changing direction and speed as the fast
moving sfc low along the WY/SD border at 09Z Sunday shifts across
our southwest counties by 15Z, and near or east of ATY by 18Z.




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