Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 011151

Area Forecast Discussion
National Weather Service Cheyenne WY
451 AM MST Thu Dec 1 2016

.SHORT TERM...(Today through Saturday)
Issued at 300 AM MST Thu Dec 1 2016

This mornings satellite imagery showing a clipper system over
western Montana moving into northwestern Wyoming. Cooling cloud
tops on IR imagery being observed across western Wyoming. Models
generally agree on snow showers developing across Carbon County
and the mountains as early as mid morning and continuing into this
evening. Not a whole lot of moisture with this system and am only
expecting a couple inches in the mountains, so no headlines

Low level winds turn northeasterly Friday afternoon with the
surface reflection of the upper shortwave moves through. Could see
some stratus and maybe some fog development Friday night into
Saturday as this happens. For now, kept it out of the forecast as
confidence is low.

Westerly winds return Saturday and could become quite gusty west
of the Laramie Range. GFS 700mb winds increase to 40kts and NAM
WRKHGT showing Craig to Casper 850 and 700mb height gradients
increasing to 51/40mtrs respectively.

.LONG TERM...(Saturday night through Wednesday)
Issued at 300 AM MST Thu Dec 1 2016

Saturday night/Sunday...Fast zonal flow aloft prevails with breezy
to windy conditions. With limited low and mid level moisture, only
isolated to scattered snow showers expected over the Snowy and
Sierra Madre Ranges, dry elsewhere. Rather mild on Sunday per
progged thicknesses and 700 mb temperatures.

Monday...Models similar in showing a cold frontal passage during the
day with much colder air infiltrating our region. Looks like
baroclinic band type snows will spread from west to east during the

Tuesday...Bitterly cold airmass filters into our forecast area with
700 mb temperatures near -20 Celsius progged and cold north winds.
Highs in the single digits and teens. Models keep the bulk of the
higher QPF to our south over Colorado, though it looks like enough
moisture and low level upslope to produce scattered to widespread
light snow over our counties.

Wednesday...Bitterly cold airmass remains entrenched over our
counties with the ECMWF progging 700 mb temperatures only around
-24 Celsius. Looks like the airmass will dry out enough for only
a few snow showers, though still quite cold.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 449 AM MST Thu Dec 1 2016

VFR prevails, except at Rawlins where periods of MVFR in snow
and low clouds will occur through 07Z, then continuously after


Issued at 300 AM MST Thu Dec 1 2016

Minimal fire weather concerns as cold temperatures remain over the
area. Winds ease through today and become light later this
afternoon and continue into Saturday. Another winter storm system
set to move into the area Sunday into Monday that may bring
widespread accumulating snow.




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