Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 101056
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
356 AM MST Tue Jan 10 2017

.SHORT TERM...(Today through Wednesday night)
Issued at 355 AM MST Tue Jan 10 2017

Progressive, energetic west to east large scale flow dominated most
of the nation. A potent short wave trough was tracking east across
the central Rocky Front Range, producing scattered rain/snow showers
and very strong gradient winds. In fact, winds increased markedly
just after midnight across central Laramie County. Gusts of 60 to
80 mph were reported, with a peak gust of 72 mph at Cheyenne. With
the gradients relaxing, winds will slowly wane overnight, but still
could briefly gust to 60 mph through early morning. Decided to extend
the High Wind Warning for WY zones 106 (Bordeaux), 117 (Vedauwoo)
and 118 (Cheyenne) for this possibility.

Forecast concerns through the short term will focus on high winds,
heavy mountain snowfall, and how far south the arctic front will
penetrate into our CWA.

Lull in winds will be brief however, with the CAG-CPR 700/850mb
gradients increasing once again by 15Z today, ranging between 60
and 80 meters through this evening. Upgraded the High Wind Watches
to Warnings for the wind prone areas today through tonight. West
to southwest winds sustained 30 to 50 mph with gusts 60 to 70 mph
are likely beginning this morning and continuing through late tonight.

Moist orographic flow will continue to promote periods of heavy snow
for the southern WY mountains through Wednesday night, which already
received between 10 and 33 inches. An additional one to three feet
is forecast through Wednesday night, heaviest over the Sierra Madre
range. Gusty winds of 35 to 45 mph will produce areas of blowing
snow with reduced visibilities.

Most areas east of the Laramie Range will continue precipitation-free
through this evening due to the drying downslope winds. The exception
will be east central WY into northwest NE as an arctic cold front
settles south tonight and Wednesday. Light snow will eventually spread
east across southeast WY and western NE later tonight and Wednesday.
The snow may mix with rain Wednesday afternoon over far southeast WY.
High temperatures today will be cooler in the wake of a Pacific cold
frontal passage with mid 30s to mid 40s. High temperatures Wednesday
will be dependent on the location of the arctic front, with teens to
the north, and 20s and 30s to the south. It will be breezy to windy
for areas along and west of the Laramie Range Wednesday and Wednesday
night.

.LONG TERM...(Thursday through Monday)
Issued at 300 AM MST Tue Jan 10 2017

A cool day expected across the CWA Thursday with a cold surface high
settling southeast out of southern Canada into the northern plains.
Some snow showers should occur over the southern mtns and adjacent
areas as some moisture rides northeast over the area from an upper
low along the California coast. This low will dig relatively far
south into far northwest Mexico through Saturday then turn northeast
across the New Mexico/Tx Panhandle region over the weekend. GFS
farther east with the track of this system and keeps the CWA dry
while latest EC has shifted westward and brushes the eastern CWA
with some pcpn Sunday into Monday. Will not yet buy into this
solution but see what later runs depict so for now will favor dry
and more seasonable weather for the CWA over the weekend through
Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 300 AM MST Tue Jan 10 2017

Mainly VFR expected through the period though some periods of MVFR
cigs possible mainly this morning around KRWL and KCDR. Higher
mtns obscured with snow showers with gusty winds affecting se Wy
from KRWL to KCYS.

&&

.FIRE WEATHER...
Issued at 245 AM MST Tue Jan 10 2017

No fire weather concerns this week. The active weather pattern will
persist through mid week as a strong jet stream brings strong winds
and heavy mountain snowfall. An arctic front will push south into
eastern Wyoming and northwest Nebraska late tonight and Wednesday,
with chances for light snow.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning until 5 AM MST Thursday for WYZ112-114.

     High Wind Warning from 7 AM this morning to 5 AM MST Wednesday
     for WYZ110-116.

     High Wind Warning until 5 AM MST Wednesday for WYZ106-117-118.

NE...None.
&&

$$

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



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