733
FXUS65 KCYS 102215
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
315 PM MST Wed Dec 10 2025

.KEY MESSAGES...

- The long duration high wind event will resume Wednesday
  morning in Carbon and Albany county, then spread into the I-25
  corridor during the afternoon. Strong winds will last into
  Thursday evening.

- The wind prone areas along I-80 and I-25 can expect another
  round of wind gusts between 70 and 80 mph. A few gusts
  exceeding 80 mph are possible.

- Cheyenne, Laramie, Rawlins, and Wheatland can expect wind
  gusts between 60 and 70 mph, but occasional lulls or breaks in
  the high winds are expected with this round.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 310 PM MST Wed Dec 10 2025

The short term remains windy, with High Wind Warnings and Watches in
effect for the usual southeast Wyoming wind prones and wind prone
adjacent areas. Most High Wind Warnings in effect have already
verified, with locations like Arlington, Muddy Gap and the Laramie
Valley nearly gusting above 60 MPH for most of the day already.
Decided to keep the current High Wind Watches in place for Shirley
Basin and Converse County. High winds look marginal in these areas,
but could still be possible, so a quick upgrade could be needed if
winds start to increase. A surface low in lee of the Laramie Range
will keep MSLP gradients along and west of the Laramie Range steep,
aiding in high winds overnight. For the most part, winds aloft
overnight will range from 50 to 60 kts with strong subsidence
helping push these winds down to the surface. There will likely be
ebbs and flows with the wind overnight with periods of high winds
and other times with lighter, more elevated wind gusts. Besides
wind, a stationary front sagging over southwest South Dakota could
send some light snow and rain showers to Dawes, Sioux and Niobrara
Counties. The window for precipitation will be brief this afternoon
and evening as a warm front is progged to move across the CWA
overnight, ushering in drier air aloft. Between the warm front and
the downsloping winds, overnight lows tonight are expected to be
quite mild, with a few locations expected to set record high low
temperatures.

Mild temperatures will continue into Thursday, again in part because
of the strong downsloping expected on top of +8C 700 mb temperatures
behind the warm front! High temperatures, mainly east of the Laramie
Range will be in the upper 50s and 60s. This is roughly 20 degrees
above average for mid-December! Sidney and Alliance will be within a
few degrees of tying their record highs. Now, back to the
winds. High winds will continue through the day Thursday as the
surface low in lee of the Laramie Range remains in place. As a
result, MSLP gradients will remain steep with 70 kt winds aloft.
Strong downward omegas will facilitate sending these winds down
to the surface, with a mountain wave signature evident as well.
Did add a High Wind Watch for East Laramie County during the
day tomorrow as both strong winds and subsidence spread further
east into the plains. Will also have to keep an eye on southern
Goshen, Scotts Bluff, Banner, and Kimball Counties as well,
since they may also briefly see high winds tomorrow. High winds
will ease Thursday evening as a front moves across the area,
turning winds more northerly. Behind the front, the northern
zones of the CWA could see some precipitation. Rain will likely
change to snow quickly with as strong of a cold front this is.
Some snow accumulation will be possible, but how much will still
need to be ironed out.

Cooler, but less windy conditions are expected on Friday. Although
winds won`t be reaching high wind criteria, it will still be a
blustery day across the southeast Wyoming wind prones. Snow showers
will linger in the northern zones of the CWA, where a stationary
boundary will be locked in place most of the day. Behind the front,
temperatures will feel much cooler with most locations seeing
highs in the 30s and 40s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 310 PM MST Wed Dec 10 2025

Global ensembles all agree that northwest flow aloft will gradually
transition to a more zonal regime this weekend as western ridging
breaks down and shifts east. With this will come some embedded
shortwave activity Friday into Saturday rounding the crest of the
ridge in the northern Rockies/northern plains and a swath of snow
from Montana to the SD/NE/IA corridor. While this snow misses us it
does bring increasing pressure gradients to the region with high
winds looking likely for the wind prone areas (I80 and I25 near
Bordeaux) Saturday. As the shortwave passes to the north/east on
Saturday afternoon the attendant cold front will surge south across
the high plains of eastern Wyoming and the Nebraska panhandle
helping to increase Craig to Casper 700mb height gradients upwards
of 70m along with 700mb winds of 55kts. In house guidance shows a 50-
80% chance of meeting high wind criteria in the wind prones but does
not show much of a signal for other areas increasing confidence that
this will be a more typical event compared to the high winds of
earlier this week.

While wind remains relatively high confidence, the placement of the
cold front remains mixed with considerable spread in temps for areas
along the front range and the high plains. Spreads of 10-20F or more
remain for any period from Saturday morning through Sunday afternoon
with highs anywhere from teens in the north to 30s in the south on
the low end (25th percentile) to 30s in the north and 50s in the
south on the high end (75th percentile). At least beyond Saturday
there is slightly less spread in temps (only 10 degrees between the
25-75th) through Tuesday evening when another cold front looks to
push south bringing temps slightly closer to average. More high
elevation looks possible by mid next week as well but amounts look
to stay on the low end (only a few inches) as we continue to play
catch up with our season to date low mountain snowpack.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1033 AM MST Wed Dec 10 2025

Winds remaining southerly to southwest through the afternoon
turning more westerly around 5-7pm for CYS and Nebraska
terminals. For RWL and LAR southwest to westerly winds through
the period with wind gusts of 40-50kts through the afternoon
before falling off slightly tonight as gradient weaken with
incoming high pressure. There will be temporary breaks or lulls
in the strong surface winds, but expect to find significant WNW
LLWS during periods when surface winds are light. Nebraska will
get a break from the gusty winds today, but expect a few gusts
around 20 to 25 knots.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Watch through Thursday afternoon for WYZ101-105.
     High Wind Warning until 5 PM MST Thursday for WYZ104-107-109-
     113-115-118.
     High Wind Warning until midnight MST Thursday night for WYZ106-
     117.
     High Wind Warning until 5 AM MST Friday for WYZ110-116.
     High Wind Watch from late tonight through Thursday afternoon
     for WYZ119.
NE...None.

&&

$$

SHORT TERM...SF
LONG TERM...WFOCYS
AVIATION...WFOCYS