462
FXUS65 KCYS 212342
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
442 PM MST Thu Nov 21 2024

.KEY MESSAGES...

- Mild weather will continue each day through Saturday as high
  pressure remains in control over southeast Wyoming and western
  Nebraska.

- Near to below normal temperatures will prevail for Sunday
  through Thanksgiving. Chances for snow will be greatest on
  Sunday and Wednesday, with drier conditions for Monday,
  Tuesday and Thanksgiving.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 133 PM MST Thu Nov 21 2024

Dry and mild weather will dominate the short term forecast
across southeast Wyoming and western Nebraska. The synoptic
pattern over the region features broad ridging that will last
all the way through the day on Saturday. Mid-level temperatures
will steadily rise on Friday and on Saturday, resulting in
above-normal afternoon highs about 10 degrees or more above
climatology for late November. Skies will generally be mostly
clear through the period, with high cirrus drifting west to east
and a few isolated mountain wave clouds aloft in the lee of the
Laramie/Snowy ranges. Expect overnight lows near to slightly
above average across most locations. By later afternoon
Saturday, southwesterly flow aloft will increase ahead of a
broad trough/frontal system moving through interior Wyoming.
500mb heights will drop through the afternoon and early evening
with thicker clouds moving in in the mid and upper levels at
this time. Surface wind flow will also increase as subsidence
ramps up in the lee of the mountains. This will favor high
winds, potentially up to high wind criteria in the Snowy Range
foothills of I-80 as well as possibly on the Laramie Range
summit. Overall forecast confidence is high through the short
term with excellent agreement in HREF and larger-scale ensemble
blends.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 133 PM MST Thu Nov 21 2024

Saturday night/Sunday...Brisk west southwest flow aloft continues
Saturday night, and based on the low and mid level gradients and our
local wind models, we may see winds near or exceeding high wind
criteria across our Wyoming wind prone locations such as Arlington,
Elk Mountain, Bordeaux and the I-80 Summit. On Sunday, a Canadian
origin cold front progresses southward across our counties with
moist west southwest flow aloft and decent low level upslope along
the spine of the Laramie Range, thus snow looks to develop from west
to east, with the greatest areal coverage over and near the Snowy
and Sierra Madre Ranges. Based on the QPF, we may need some type of
winter weather highlights for our mountains and nearby lower
elevations. With 700 mb temperatures falling considerably, maximum
temperatures will be significantly colder compared to Saturday.

Monday...Low amplitude shortwave ridging aloft moves overhead with
moist flow aloft lessening during the day, allowing the areal
coverage of snow to decrease to scattered snow showers for the Snowy
and Sierra Madre Ranges by afternoon. 700 mb temperatures near -5
Celsius will continue the cold high temperatures from the mid 30s to
lower 40s.

Tuesday...The moist zonal, west to east, flow aloft will continue to
produce scattered to numerous orographic snow showers for our Snowy
and Sierra Madre Ranges, with cloud cover for other locations.
Slightly warmer than Monday based on 700 mb temperatures.

Wednesday...Both the GFS and ECMWF indicate trofiness aloft over
Wyoming with enough low and mid level moisture to produce scattered
to numerous snow showers and colder temperatures in the wake of a
cold frontal passage.

Thanksgiving...The holiday looks like a windy and cold day with
brisk northwest flow aloft and decent low and mid level gradients to
produce blustery conditions, 700 mb temperatures near -12 Celsius
will yield maximum temperatures in the 30s, which will feel even
colder due to the blustery conditions.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 439 PM MST Thu Nov 21 2024

No aviation concerns for the TAF period. A ridge of high
pressure over the Rockies will keep any weather at bay. Some
high level clouds will float overhead tonight and into the day
tomorrow. Winds will remain light and variable overnight at most
terminals, with light winds continuing into the day tomorrow.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.

&&

$$

SHORT TERM...MAC
LONG TERM...RUBIN
AVIATION...SF