Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 200931

Area Forecast Discussion
National Weather Service Goodland KS
231 AM MST Sat Jan 20 2018

.SHORT TERM...(Today through Monday night)
Issued at 231 AM MST Sat Jan 20 2018

Across the Tri State region this morning...temperatures are ranging
widely this morning from the mid 20s up to the lower 30s w/ mainly
clear skies and light winds.

Going into more nice above normal day for temps is set
for the area with the remnants of the upper ridge slowly breaking
down ahead of a storm system for the latter half of the weekend. Low
pressure at the surface will aid in bringing in some WAA into the
region allowing for daytime highs to reach mainly into the 50s...w/
some lower 60s possible over SW zones.

For tonight and on thru Sunday night...this timeframe will be the
main wx concern for the area. A storm system working east from the
west coast will enter the central Rockies later tonight...close off
and work eastward into the central Plains Sunday and Sunday night.
Models fairly close to consistency on its track w/ latest runs. Cold
air working into the region tonight onward will bring about wintry
precip. Low level moisture working into the region tonight will
overspread the region going into Sunday. This will allow some light
freezing rain to start over the area...transitioning to snowfall as
Sunday progresses. Expected low track will allow for heaviest snow
totals along and north of Interstate 70 at this time.

Also of concern will be the strong northerly winds that will
accompany the expected snowfall from midday Sunday onward. Latest
guidance suggest sustained 30-40 mph with gusts to 50 mph. These
strong winds will create near blizzard-like conditions thru Sunday

With these expected conditions for the region...have upgraded the
entire CWA to a Winter Storm Warning from 06z Sunday thru 12z
Monday. Snowfall totals will range from 3-7" along and south of
Interstate 70...with 5-8" (and locally higher amounts near 10+
inches)north of the Interstate. This snowfall combined with expected
winds and light glaze of ice will have a big impact for the region.

Please stay tuned for further updates as any slight change in the
track of the storm will have a big impact on area conditions.

Region clears fairly quickly going into Monday/Monday night with
high pressure returning to the area.

For temps...highs Sunday in the lower to mid 30s will give way to 35-
45F on Monday. Overnight lows in the teens to lower 20s.

.LONG TERM...(Saturday night through Friday)
Issued at 230 PM MST Fri Jan 19 2018

Overview (Sat night-Sun Night):
A shortwave trough situated just offshore the Pacific Coast this
afternoon will progress ashore central/southern CA coast tonight.
This feature is progged to amplify into an upper level low as it
progresses east to the 4-Corners region late Sat/Sat night, with
further amplification expected as it emerges east of the Rockies
onto the High Plains. An attendant surface low is progged to
develop invof the Oklahoma Panhandle (Sunday morning), then track
northeast through southern/eastern KS (Sunday afternoon) into
central IA (Sunday night).

The 12Z operational GFS/ECMWF, while in good agreement on the
overall pattern, differ (by nearly a factor of 2 in areas) with
regard to the distribution/amount of precipitation across the Tri-
State region. Both models continue to indicate that the Tri-State
region will be located along the southern periphery of a
developing deformation band on the western periphery of a
deepening sfc cyclone during the day Sunday, with liquid
equivalent precip ranging from 0.30"-0.50" near the KS/NE/CO
border to 0.10"-0.20" in southern portions (Tribune/Leoti). A
PERFECT PROG of these solutions would yield predominately snow
(short period of fzdz/fzra possible at onset along/east of Hwy
83), with potential snow accum ranging from 4-7" along/north of
the I-70 corridor and 1-3" south of I-70. Strong NW winds (gusting
to 45-55 mph) continue to be expected Sun afternoon/evening in
association with a tight MSLP gradient /pressure rises/ on the
western periphery of the deepening/departing sfc cyclone, in
addition to enhanced mixing associated with low-level cold
advection coincident with lingering precipitation /evap cooling/.

Forecast Confidence Remains Very Low with regard to precipitation
distribution/amounts given that the Tri-State region is progged to
be on the southern periphery of a developing deformation band
attendant a cyclone that will not develop for another 36-42 hours
and whose parent upper level wave will not move ashore the Pacific
Coast until late tonight. Given that the 12Z operational runs of
the ECMWF/GFS indicate increased precipitation amounts compared to
the same time yesterday and that strong NW winds would result in
significant reductions in visibility (potential for brief/
localized blizzard conditions) in the presence of mdt/hvy snow
Sunday afternoon/evening, a Winter Storm Watch has been issued for
areas along/north of Interstate 70.

Potential Impacts:

1) Brief period of FZDZ invof I-70 possible in northwest KS Sun AM
2) Snow accum approaching 6" along/north of I-70, less to the south
3) N/NW winds gusting to 45-55 mph Sunday aft/eve
4) Significant reductions in visibility associated with blowing
   snow possible Sun aft into Sun night, esp along/north of I-70

At this time, expect dry conditions and large diurnal temperature
ranges Mon-Thu night in assoc/w a period of NW flow aloft in the
wake of the amplifying upper low /attendant sfc cyclone/
progressing toward the Great Lakes, followed by shortwave ridging
aloft. 12Z guidance indicates some potential for precipitation in
assoc/w another upper trough traversing the Rockies late next week
(Fri/Sat), though at 168+ hours out in a progressive synoptic
pattern, confidence is as low as it gets.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1037 PM MST Fri Jan 19 2018

Vfr conditions are expected until late in this forecast period.
Also the winds at both sites will be from 6 to 9 knots at their
strongest. For Kgld, light and variable winds will shift to the
northeast around 15z and then back to southeast around 21z. Those
winds turn to the east then northeast during the late afternoon
into early evening. From near 03z to the end of the period mvfr
conditions will develop.

For Kmck, north winds will continue for the first half of the
period. At 18z through the end of the period those winds between
northeast and east. From near 03z to the end of the period mvfr
conditions will develop.


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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