Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 130442

Area Forecast Discussion
National Weather Service Cheyenne WY
1042 PM MDT Thu Apr 12 2018

Issued at 745 PM MDT Thu Apr 12 2018

Another update here this evening, to cancel the High Wind Warning
that was in effect for the southern Laramie Range & I-25 corridor
this evening. Winds have weakened this evening, thus no longer
warranting the High Wind Warning. Also increased precipitation
chances across much of the area overnight per latest KCYS 88D
radar returns. Don`t think that this activity will amount to a
whole lot overnight, but there were certainly be showers around.
Otherwise, made no significant changes to the forecast as we
continue to highlight the very poor traveling conditions across
the Panhandle tomorrow.

UPDATE Issued at 602 PM MDT Thu Apr 12 2018

Winds have drifted lower over across the Laramie Valley over the
past few hours, with gusts generally in the 30-40 mph as of 6 PM.
So, went ahead and let the High Wind Warning expire on schedule
at 6 PM for the Laramie Valley. Wind speeds in the warned area of
the southern Laramie Range, Platte County, and Central Laramie
County, remain in the 35-45 mph range currently. Will watch trends
over the next few hours for these area, as I suspect that this
area may be cancelled early.


.SHORT TERM...(This evening through Friday night)
Issued at 245 PM MDT Thu Apr 12 2018

Quite varied weather expected over the next 36 hours as an upper low
deepens over Colorado overnight then moves out into the central plains
Friday. A cold front is currently moving east across the CWA and nearing
Laramie. The front will continue to sweep east through this evening.
Still appears there will be a period of stronger winds behind the front
so will maintain the current high wind warning. A few showers out west
should continue into this evening then should see some increase in
showers with maybe even a few storms over the Panhandle this evening
as the front move over that area. Some indication of dry slotting over
the plains overnight but then should see rain and snow build south
later tonight as the surface and upper lows edge into the plains,
continuing through Friday, all snow on Friday. Winds also increasing
later tonight and Friday especially east of the mtns. Have upgraded
the WS watch to a warning. Held off on a blizzard warning as snow
intensities not looking too great at this time but will have to
watch especially in the Chadron to Alliance area. Snow will taper
off Friday evening as the system pulls away but gusty winds will

.LONG TERM...(Saturday through Thursday)
Issued at 245 PM MDT Thu Apr 12 2018

Medium range models/ensembles are in good agreement with the progressive,
amplified large scale flow. Vigorous late season storm over the eastern
Great Plains Saturday morning tracks slowly east toward the Middle MS
Valley through Sunday. Meanwhile, a upper ridge slides eastward across
the Rockies and into the Great Plains Sunday through Monday.

Northerly winds will diminish through the day Saturday with the relaxing
pressure gradient. Cooler than normal temperatures will continue Saturday
with highs in the 30s and 40s. Temperatures rebound to above normal
by Monday, with highs back into the 50s Sunday, and 60s to lower 70s
Monday. South to southwest winds will be breezy Monday, with stronger
winds Monday night across Carbon County. Next upper trough and cold
front affect the CWA Tuesday with scattered rain/snow showers and cooler
temperatures. Wednesday will be breezy and cool with highs in the 40s
and 50s. Milder and continued breezy Thursday ahead of yet another
Pacific upper trough, which may bring more wintry weather to the
CWA by next weekend.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1042 PM MDT Thu Apr 12 2018

Deteriorating conditions expected at all terminals through this
TAF cycle as an area of low pressure intensifies. All airfields
will be VFR to begin the period, but this will deteriorate quickly
as MVFR/IFR conditions develop 08-15z. Initially temps warm enough
for -RA, however strengthening low pressure area will pull colder
temperatures south, turning everything over to -SN by 12z. SE WY
terminals and KBFF can expect generally 1-3 inches of snow, with
widespread 5-10 inches at other KCDR, KAIA, and KSNY. The
combination of accumulating snow and northwest winds that will
gust to between 35 and 50 knots during the day Friday will produce
near-blizzard conditions at times. Conditions will gradually begin
to improve after 03z Saturday.


Issued at 245 PM MDT Thu Apr 12 2018

Fire weather concerns will diminish this evening as a cold front moves
across the area. Concerns will remain low through the weekend with
cooler temperatures and some rain and snow, especially on Friday. Very
strong winds expected east of the mountains Friday.


WY...Winter Storm Warning from 6 AM Friday to midnight MDT Friday
     night for WYZ102.

     High Wind Warning from 10 AM Friday to midnight MDT Friday night
     for WYZ106>108-117>119.

     Winter Weather Advisory until midnight MDT Friday night for

NE...Winter Storm Warning from 6 AM Friday to midnight MDT Friday
     night for NEZ002-003-019-021-055-095-096.

     High Wind Warning from 10 AM Friday to midnight MDT Friday night
     for NEZ020-054.



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