Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 202223

Area Forecast Discussion
National Weather Service Goodland KS
323 PM MST Sat Jan 20 2018

.SHORT TERM...(This evening through Monday)
Issued at 323 PM MST Sat Jan 20 2018

Deepening trough is in place over the Great Basin with southwest
flow across the Central High Plains, and this is the system we are
tracking for Sunday through Monday morning. At the surface, a
stationary front is in place just south of our CWA, with surface
low pressure over southeast Colorado.

Primary concern is potential for a significant winter storm expected
to develop Sunday and continue through Monday.

Tonight-Sunday morning: Low level moisture is shown to increase in
east-northeast boundary layer flow and guidance shows potential for
freezing fog late this evening and after midnight, and eventually
freezing drizzle as depth of saturated layer increases. Overall
precip signal is very light and saturated layer may not be deep
enough for more than a light glaze. There is a period where moisture
advection increases during the late morning hours and a few
hundredths of an inch of icing could develop.

Sunday afternoon-Monday morning: Trough become negatively tilted and
tracks within favorable region from southeast Colorado (around 18Z)
and near our southeast CWA through Sunday night. Deformation zone
developed in northeast Colorado and slides eastward, and in this
region heavy snow should develop. GFS is currently the most
disorganized on forcing/moisture advection, while NAM/GEM/ECMWF are
matching reasonably well on heavy snow signal from I-70 north.
Locations south are much less certain. It is possible that if there
is instability (as indicated by NAM) we are running too low on
amounts in our north by 2-3", and almost all guidance is trending
lower on amounts in our south where we could be running 1-3" too
high. Most snowfall should be ending west to east after 3 AM MST (4
AM CST), with light snow possibly lingering through late Monday

All guidance is showing windy conditions, and there is a concern that
winds on the back side of this system may approach warning criteria
(58mph or higher). This occurs as the main deformation zone
transitions east, which lowers confidence on possible Blizzard
conditions (1/4sm or less). Reduced visibilities 1 mile or less appear
likely, and if this timing of the strongest winds pans out we may
see ground blizzard develop Monday morning for a brief period as the
strongest wind axis shifts eastward. There was discussion about
issuance of Blizzard Warning, however ultimately the lack of
confidence in a prolonged threat of whiteout conditions led us to
hold onto the current Winter Storm Warning.

Monday afternoon: Conditions should be dry, however complications
of possible snow pack could lead to much lower afternoon temps
despite possible clearing. Windy conditions may linger in our
east, but with temperatures at least approaching freezing (if not
above) under sunny skies, we should see the blowing snow threat
diminish (due to settling/crusting).

.LONG TERM...(Monday night through Saturday) Issued at 254 PM MST
Sat Jan 20 2018

High pressure begins to move into the region as the storm system
moves further out of the area Monday night through Tuesday night
and the upper western U.S. ridge moving across the Rockies and
High Plains regions on Wednesday and Thursday.

The lee trough deepens over the high plains on Thursday night into
mid day Friday ahead of the next larger scale upper trough to affect
the forecast area between Friday and Saturday.  Ahead of this next
system, daytime highs are expected to rise into the 40s and 50s with
lows mainly in the 20s.  Friday could see a light mix of rain and
snow with a transition to all snow Friday evening as temperatures
drop below freezing. The system continues to pass through high
plains into the central plains as an open wave on Saturday and
Saturday night with much of the system dynamics circumnavigating the
forecast area. Therefore only expect light rain/snow accumulations
at this point between mid day on Friday and late Friday evening.
High temperatures on Saturday will be back down in the 30s with
lows in the teens.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1036 AM MST Sat Jan 20 2018

Winter storm to impact the TAFs during the latter half of the
18-18Z TAF period.

Both GLD and MCK will start out VFR with only high clouds through
the remainder of this afternoon and into this evening. After 05Z,
lower clouds with MVFR ceilings begin to spread across the
central high plains region with light northeast winds. Ceilings
will continue to lower through the overnight hours with
intermittent IFR conditions between 06-08Z and IFR to LIFR
conditions after 08Z. There may be instances of light freezing
drizzle after 08Z that transitions to light snow by 15Z, but
confidence is low on freezing precipitation. Have gone with a
prevailing light snow across the area along with gusty north
northeast winds after 15Z Sunday morning.


KS...Winter Storm Warning from 11 PM MST /midnight CST/ this evening
     to 5 AM MST /6 AM CST/ Monday for KSZ001>004-013>016-

CO...Winter Storm Warning from 11 PM this evening to 5 AM MST Monday
     for COZ090>092.

NE...Winter Storm Warning from 11 PM MST /midnight CST/ this evening
     to 5 AM MST /6 AM CST/ Monday for NEZ079>081.



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