940
FXUS65 KCYS 202148
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
248 PM MST Thu Nov 20 2025

.KEY MESSAGES...

- Model disagreement and variability remains high for the up-
  coming system tonight into early Friday morning. Snow
  accumulations have generally decreased with recent model runs
  with 1-2 inches being the consensus.

- Second system with another shot of rain and possible snow hits
  our southeastern zones early in the week with a deep Canadian
  low and trough bringing notably colder temperatures just
  before and through the holiday timeframe next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 248 PM MST Thu Nov 20 2025

A low pressure system is going to be pushing through the Southwest
portion of the United States and the lower part of Colorado. Model
agreement has been anything but over the past couple days and still
have some disagreement in the track of the system. Unfortunately for
this forecast area we are on the fringe of this event making this
forecast particularly difficult in who is going to get precipitation
and who is not as well as how much if they do. Hi-res guidance
generally has low accumulations for areas that each model decides
has the best chance at getting precipitation. With this system
starting south and pushing east southeast. Low pops were given to
Carbon county outside the mountains as majority of the models did
not show any showers or forcing affecting that particular area.
However, models did show a stream of vorticity particularly parked
over the I-80 corridor between Cheyenne and Sidney, Nebraska between
9z and 18z Friday with the stream flexing over the panhandle between
18z Friday and 00z Saturday as the system pushes east. The other
piece of this equation that is kind of hard is deciding how is the
precipitation going to fall. For the vast majority of the Panhandle
it will stay as rain as temperatures (both ambient and wetbulb)
remain too warm to fall as snow. The initial rain/snow line
generally appears to be somewhere in the western portion of Laramie
county most likely near the foothills. However, that line will shift
east in Laramie as the rain will start to transition to snow
resulting in some light accumulations east of the foothills and
summit. Hi-res guidance is also conflicted about how far east that
line moves with some models depicting no movement in that line to
begin with. For most of Laramie county, Wyoming some light snow
accumulations were added along the I-80 corridor and a little bit
north of the corridor as well. Friday afternoon the precipitation
will slowly taper off in Southeast Wyoming ending by the late
afternoon. The Nebraska Panhandle is closer to the systems pivot
point so precipitation will last longer with precipitation generally
ending by the ending and possibly later if the system does slow down
and pops were decreased to quickly. As this system pushes east a
short lived ridge pushes into the Intermountain West starting
Saturday morning.


&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Issued at 248 PM MST Thu Nov 20 2025

Long term is quite active as we see a second low skirt by to our
south with the strongest impacts remaining outside of our CWA
again but another shot of precipitation is likely for our
southern zones. Following this, a deep upper level trough will
move in from the Pacific and a cutoff low will form along the
border of the US/Canada, sweeping a cold front across the CWA by
Tuesday morning that will cause our temperatures to plummet, as
well as produce further precipitation that will be more
widespread.

The long term begins on Saturday in between southern tracking
low pressure systems, generally with our region out of direct
influence of any one feature though weak transient ridging will
pass across into the later part of the weekend. Benign
conditions and still warmer than average temperatures will
linger through Sunday morning, but by the afternoon the next low
to track to our south passes across with once again the bulk of
any major influence just outside of our region. Still, another
glancing blow of precipitation is expected for our southeastern
zones, with light accumulations of rain and some mixing into
snow expected, primarily along and just east of the Laramie
range. But as we move into Monday, we`ll see a noteworthy
pattern change as a deep trough moves in from the Pacific and a
cutoff low forms along the US/Canadian border. This system will
be accompanied by a stout cold airmass, and while we won`t be
reaching record cold by any means, it`ll be our first real
powerful shot of a colder winter style airmass. Highs are
expected to drop into the widespread 30`s to low 40`s by
Tuesday behind the front, alongside lows in the teens to mid
20`s. These temperatures should hold through the Thanksgiving
holiday under northwesterly flow on the backside of this trough.
Meanwhile, we should see multiple bouts of precipitation during
this timeframe, with the bulk of it occurring in the higher
terrain of our western zones but sometimes spilling into the
lower terrain and high plains to the east. Overall the moisture
available will be minimal, but we should still see several
inches of snow accumulation potential, highest in the mountains
of course but occasionally down into the lower elevations and
with temperatures as cold as they are expected, remaining snow
as it occurs down here as well. Winter-like conditions are here
to greet us as we approach the holiday!

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1048 AM MST Thu Nov 20 2025

Some lingering low clouds and reduced visibilities are noted in
the Nebraska Panhandle this morning, but should be lifting over
the next hour or two. This afternoon and evening, a system will
move in and bring MVFR through LIFR conditions (both lowered
CIGs and VIS) to all sites alongside areas of precipitation.
Sites KCYS/KLAR have a chance at this mixing or fully becoming
snowfall, which could further reduce visibilities and bring
further hazardous conditions. Light precipitation could even
become patchy fog. Winds should remain low through this event
though, generally 10 knots or less.

&&

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

&&

$$

SHORT TERM...MM
LONG TERM...CG
AVIATION...CG