Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 081125
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
425 AM MST Wed Dec 8 2021

.SHORT TERM...(Today and Thursday)
Issued at 345 AM MST Wed Dec 8 2021

High Wind Warnings remain in effect today and tonight for many
areas along and adjacent to the Laramie Range in addition to the
Arlington/Elk Mountain area. Strong downward omega with an
increasing pressure gradient across the Laramie Range will support
high wind potential today. 700mb flow currently sits around 45kts
and increases later today. The Bordeaux gap area along Interstate
25 between Chugwater and Wheatland just recently gusted to 71 MPH
at 3:14 AM MST and local in-house probabilities for high winds
only increases headed into later today. Overall, expecting a windy
day for SE WY wind-prone areas in addition to the adjacent plains.
Downsloping winds off the Laramie Range under a brief ridging
pattern will also help raise temperatures across eastern Wyoming
and western Nebraska into the upper-50s.

Late this afternoon, a compact shortwave currently positioned over
southern NV will pass through central CO and could support some
weak forcing over the Sierra Madre Range. Snowfall should remain
light ahead of the main event later on Thursday into Friday.

Winds will begin to calm down late tonight and early Thursday
morning with pressure rises over east-central Wyoming with the
arrival of colder air decreasing gradients across the Laramie
Range. Additionally, an approaching open wave will support lee
cyclogenesis to the south in CO. Much of southeast Wyoming and
western Nebraska will be positioned along the right entrance
region of a 150+ kt jet by late Thursday afternoon. Heaviest
snowfall during the day Thursday will be west of the Laramie
Range, especially in the Sierra Madre and Snowy Ranges, before
spreading farther east during the late afternoon and overnight
hours.

.LONG TERM...(Thursday night through Tuesday)
Issued at 345 AM MST Wed Dec 8 2021

Thursday night/Friday...A progressive shortwave trough aloft is
projected to move overhead, spreading decent chances for
accumulating snowfall across our counties, along with colder
temperatures. Many locations could see advisory or warning level
snowfall totals, thus necessitating the need for Winter Storm
Watches.

Saturday...Blustery and windy in the wake of the passing shortwave
trough aloft and with strong northwest flow aloft. Drying trend
behind the shortwave trough aloft.

Sunday-Tuesday...Another warming trend begins as the flow aloft
turns southwest with surface lee troughing developing and
700 mb temperatures rising each day. With limited low and mid level
moisture, precipitation chances look slim.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 421 AM MST Wed Dec 8 2021

Wyoming TAFS...VFR, with low VFR developing at Rawlins after 06Z.
Wind gusts to 40 knots. Low level wind shear at Laramie and
Cheyenne until 15Z or 16Z.

Nebraska TAFS...VFR. Wind gusts to 25 knots at Chadron, Alliance
and Sidney from 16Z to 00Z. Low level wind shear at Scottsbluff
and Sidney until 16Z or 17Z.

&&

.FIRE WEATHER...
Issued at 345 AM MST Wed Dec 8 2021

Warmer today with windy conditions across much of the area.
Downsloping winds off the Laramie Range and temperatures running
10-15 degrees above average will drive afternoon RHs into the 20s
for most location. Minimal fire weather concerns the rest of the
week as cooler weather arrives along with widespread snowfall
across the area early Thursday morning through Friday afternoon.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Watch from late tonight through Friday morning for
     WYZ103>105-109>111.

     High Wind Warning until 5 AM MST Thursday for WYZ106-107-116-117.

     Winter Storm Watch from Thursday morning through Friday
     afternoon for WYZ101-102-106>108-116-117.

     High Wind Warning until 11 PM MST this evening for WYZ101.

     Winter Storm Watch from this evening through Friday afternoon
     for WYZ112-114.

     High Wind Warning until 2 AM MST Thursday for WYZ110.

NE...Winter Storm Watch from Thursday afternoon through Friday
     afternoon for NEZ002-003-019>021-095-096.

&&

$$

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


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