Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 192129

Area Forecast Discussion
National Weather Service Goodland KS
229 PM MST Fri Jan 19 2018

.SHORT TERM...(This evening through Saturday)
Issued at 130 PM MST Fri Jan 19 2018

Expect another mild (compared to normal) evening under a varying
degree of high clouds with variable winds under 10 mph. Low
temperatures should range from the low/mid 20s across the far
northeast/east/southwest to around 30 across the west and along the
CO/KS border.

On Saturday surface winds will start to shift to the northeast
(along and north of the interstate) by 18z and a little further
south by late in the day as some cooler air filters in from the
northeast. Looking for high temperatures to range from around 50
along and north of the Kansas Nebraska border to the mid/maybe
upper 60s across the far south (Tribune to Leoti). Will have to
continue with varying thicknesses of high clouds from time to time
as well.

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

...Winter Storm Watch in Effect Saturday Night through Sunday

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 18Z TAFS through 18Z Saturday afternoon)
Issued at 915 AM MST Fri Jan 19 2018

For KGLD and KMCK, vfr conditions through the period. Both
terminals will see varying degrees of cirrus through the period.

KGLD will have west to west-northwest winds near 12kts through 20z
before veering to the northwest under 10kts through 23z. From
00z-15z winds become light from the southwest then variable after
16z ahead of an approaching cold front.

KMCK will have a light west wind through 22z then variable under
6kts from the rest of the period. Winds in this time frame will
slowly and gradually become northeast and east toward the end of
the period as a cold front moves through.


KS...Winter Storm Watch from Saturday evening through late Sunday
     night for KSZ001>004-013>016.

CO...Winter Storm Watch from Saturday evening through late Sunday
     night for COZ090-091.

NE...Winter Storm Watch from Saturday evening through late Sunday
     night for NEZ079>081.



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