Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 201201
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
501 AM MST Mon Nov 20 2017

.SHORT TERM...(Today through Wednesday)
Issued at 300 AM MST Mon Nov 20 2017

Winds the main forecast challenge today. They are already going
along and west of Laramie Range this morning.

Currently...Upper low visible on water vapor imagery this morning
tracking across northern Montana and as expected, winds are really
going to town out west. Camp Creek RAWS site just west of Muddy
Gap gusting in the upper 70s, Quealy Dome on I-80 in the Laramie
Valley hit 66mph earlier and the Summit is hitting fairly
widespread gusts above 60 mph so far this morning. With whats
going on at Camp Creek and Quealy Dome, decided to upgrade
previous watch and start it this morning instead of 11AM. Updates
have been sent on those upgrades.

Question continues for zones east of the Laramie Range. GFS
continues to showing +50kts right off the surface on both the GFS
and NAM soundings. Looks like we should easily mix into those
stronger winds on both soundings here at Cheyenne and possibly
Douglas, so went ahead and upgraded these watches to warnings as
well. GFS 750 and 800mb winds close to 60kts over Platte and
Goshen Counties this afternoon. Day crew may need to add Goshen
County into the warning if trends show winds hitting out there at
Torrington later this morning.

Pretty quick shot of snow over the Snowy and Sierra Madre Ranges
today/tonight and thats another area to watch. Am only getting 4
inches of snow in the Snowy Range in the forecast grids, but day
shift will need to monitor SNOTELS for heavier rates. Will hold
off on any advisories, but needs to be watched closely. Light
snow may continue out over the Snowy/Sierra Madre Ranges through
Tuesday before easing off.

.LONG TERM...(Wednesday night through Sunday)
Issued at 300 AM  MST Mon Nov 20 2017

Thanksgiving...Dry, mild and windy for the holiday with brisk
northwest flow aloft and decent surface lee troughing. Maximum
temperatures will climb into the 60s east of I-25 with 700 mb
temperatures near 5 Celsius.

Friday...Slightly cooler with a fast moving shortwave trough aloft
passage. Low and mid level moisture too scant for any precipitation.

Saturday...Warming trend begins anew as ridging aloft develops
across the Great Basin states with strengthening northwest flow
aloft over our counties, producing another windy day with near high
wind criteria winds possible across our wind prone locations. Dry
again with lack of low and mid level moisture.

Sunday...Ridge aloft moves overhead though with little temperature
changes noted. Lack of low and mid level moisture precludes mention
of precipitation.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 459 AM MST Mon Nov 20 2017

Wyoming TAFS...VFR, except MVFR at Rawlins after 06Z tonight. Wind
gusts to 49 knots through 00Z.

Nebraska TAFS...VFR. Wind gusts to 35 knots through 00Z.

&&

.FIRE WEATHER...
Issued at 330 AM MST Mon Nov 20 2017

Elevated to locally critical fire weather conditions across the
southern Nebraska Panhandle and extreme southeast Wyoming today
(FWZ 310 and 313). Low pressure system tracking across Montana
today will increase winds over the area with many High WInd
Warnings in effect across southeast Wyoming. Downsloping winds off
the Laramie Range will create locally critical humidity across
southern 310 and 313 along with wind gusts exceeding 35 mph. Look
for increasing chances for some precipitation when the associated
cold front moves through tonight into Tuesday.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 8 PM MST this evening for WYZ106-110-116-
     117.

     High Wind Warning from 11 AM this morning to 5 PM MST this
     afternoon for WYZ101-107-118.

     High Wind Warning until 5 PM MST this afternoon for WYZ104-105-
     115.

NE...None.
&&

$$

SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...GCC



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