Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 130007
AFDCYS

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

.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
continue.

.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 00Z TAFS through 00Z Friday evening)
Issued at 607 PM MDT Thu Apr 12 2018

Deteriorating conditions expected at all terminals through this
TAF cycle as an area of low pressure bears down. Many areas remain
VFR to begin the period, with the exception of MVFR at KRWL from a
recent snow band. This will be short-lived at KRWL with the next
round of MVFR conditions not anticipated until after 11z. VFR
conditions are anticipated at KLAR and KCYS until 18z, with -SN
developing thereafter. Conditions will drop to MVFR at western
Nebraska sites between 06-12z, with likely IFR/LIFR in SN at
least for KCDR, KAIA, and KSNY after 18z.

&&

.FIRE WEATHER...
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.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
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.

     High Wind Warning until 6 PM MDT this evening for WYZ105-115.

     High Wind Warning until 10 PM MDT this evening for WYZ106-107-
     116>118.

     Winter Weather Advisory until midnight MDT Friday night for
     WYZ112-114.

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.

&&

$$

UPDATE...CAH
SHORT TERM...RE
LONG TERM...MAJ
AVIATION...CAH
FIRE WEATHER...RE



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