Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 190312 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
912 PM CST Thu Jan 18 2018

Issued at 912 PM CST Thu Jan 18 2018

Abundant cirrus streaming over the region this evening allowing
temperatures to stay in the lower 30s as of 9 pm. Expect this
trend to continue with temperatures only falling into the mid to
upper 20s by morning.

UPDATE Issued at 533 PM CST Thu Jan 18 2018

00z aviation discussion updated below.


.SHORT TERM...(This Evening through Friday)
Issued at 236 PM CST Thu Jan 18 2018

A fairly solid swath of cirrus clouds has prevented
temperatures from reaching their maximum potential this afternoon.
Clouds will break up in patches overnight making the low
temperatures forecast rather challenging. Areas that keep the cloud
cover will not fall as quickly or as low as areas that see clear

Upper level ridging will continue to draw up warmer air into the
region. Temperatures will be well above average on Friday especially
since clouds will not be as numerous and a passing weak, dry front
will aid in mixing. Forecast highs are in the 40s.

.LONG TERM...(Friday Night through Thursday)
Issued at 236 PM CST Thu Jan 18 2018

Still the main focus in the long term is the potential winter storm.
Models remain consistent with the development of a Colorado Low that
will lift across the Central Plains into the Western Lakes regions
late Saturday through the day Monday. Initially we will see a band
of warm advection/elevated forcing across central South Dakota
(Saturday PM), with generally light QPF and I suspect is somewhat
overdone by guidance, though they all represent some aspect of it
generating precipitation. Top down within this feature supports
snow, but there is a shallow dry layer with temperatures at/just
above freezing so snow may also initially sublimate/melt.

As the shortwave and surface low kick out into the Central Plains
mid-day Sunday, the precipitation axis pivots across the CWA and we
see a reorganization of better forcing on the backside of the low,
with the focus for precipitation move across the southern tier of the
CWA. TROWAL snowfall lingers across eastern South Dakota into
western Minnesota Monday.  Typical of this type system, though
despite PWATS only around 1/2 inch (which is a little low for the
type of system (yet high climatologically because we don`t get many
Colorado lows this early in the year)), liquid equivalent snowfall
range is around 10 to 14:1 though in the best forcing area (which
the GFS tops out around 30-40 microbars) ratios could go up to 20:1.

We continue to see a wide spread in the GEFS/SREF outputs for
QPF/snow as the GFS/EC/Canadian deterministic guidance also has minor
variations in speed/track and depth of the low, which is having a
huge impact on expected outcomes. Too early at this point for any
headlines but it looks like some parts of the CWA will experience
hazardous winter conditions going into Monday.


.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 533 PM CST Thu Jan 18 2018

VFR conditions are expected through tonight and Friday at all




LONG TERM...Connelly
AVIATION...Mohr is the U.S. government's official web portal to all federal, state and local government web resources and services.