648
FXUS65 KGJT 070452
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
952 PM MST Sat Dec 6 2025

.KEY MESSAGES...

- Moderate to heavy snow rates and strong winds have
  materialized over the Colorado High Country creating hazardous
  travel conditons. Winter Storm Warnings and Winter Weather
  Advisories are in effect through this evening and into Sunday
  morning.

- Unsettled weather continues through the coming work week in
  the northern Colorado mountains with mostly periods of light
  snow showers.

- A general warming trend is expected, but the snow covered
  mountains valleys will see cold inversions set up overnight
  lasting through the days.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 132 PM MST Sat Dec 6 2025

The plume of moisture bringing precipitation to the area now
will drop to our south this evening. Weak cold advection in
northwest flow will keep orographic snow showers going in the
northern mountains and perhaps some of the central mountains.
Increasing snow to liquid ratios could turn this minor QPF into
several inches for the higher terrain especially the Park Range.
Most valleys shut off this evening. Winds decrease tonight but
remain breezy along the peaks and ridges, which may contribute
to blowing snow after the snow ends. Clouds clear out across the
south so sheltered valleys with new snow may get pretty chilly.
Most locations are dry tomorrow as northwest flow continues.
However another weak plume of moisture reaches the northern
mountains so snow showers could develop later in the day. High
temperatures tomorrow do not change much as the cold air
arriving tonight struggles to drop south.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 132 PM MST Sat Dec 6 2025

The beginning of the long term period is characterized by
generally quiet weather for all but the northern Colorado
mountains, which are expected to receive somewhat continuous
snowfall while persisting northwesterly flow supports orographic
lift. Atmospheric moisture amounts through the day Monday are
expected to be pretty close to average for this time of the
year, so any snowfall during this time period should be light.

An atmospheric river looks to move through the Rocky Mountain
region beginning Monday night, and is expected to move into our
CWA from the north overnight Monday into Tuesday. Despite to
abundance of moisture from the atmospheric river, synoptic
forcing will be limited due to a broad region of high pressure
over the Pacific which will keep ridging in place over much of
the West. It also appears there will not be good jet support
during the timing of the moisture advection, but disturbances
within the mean flow should be able to provide a bit of support
for snowfall rates to increase at times. The high pressure to
our west keeps our region under northwesterly flow, which will
continue to support orographic lift in the northern mountains.
Thus, the northern mountains look to be favored for receiving
the most snowfall from this event.

However, there is still a lot of uncertainty regarding the
details. The GFS Ens seems to be suggesting a stronger
atmospheric river than the ECMWF Ens is, so the GFS Ens is
favoring much higher snow totals. There is also significant
disagreement between ensemble members, more so among members of
the ECMWF Ens than the GFS Ens. Another potential concern will
be temperatures during this event, as temperatures are expected
to be well above normal through the long term, potentially
leading to daytime highs near or above freezing in some of the
higher terrain. Once there is better agreement between models on
the strength of this atmospheric river, and temperatures, there
will be greater confidence regarding snow totals.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 948 PM MST Sat Dec 6 2025

Snow has ended at most terminals with only a couple of
tempo groups remaining for the central CO mountain terminals.
Clouds will continue to improve into Sunday, but ILS breakpoints
are likely to continue through the overnight hours at terminals
that have not dropped their flight restrictions yet. Calmer,
sunnier conditions are on tap for the second half of the
forecast period at all sites.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Storm Warning until 5 AM MST Sunday for COZ004.
     Winter Weather Advisory until 11 PM MST this evening for
     COZ005-008-009-018.
     Winter Storm Warning until 11 PM MST this evening for COZ010-
     012-013.
UT...None.

&&

$$

SHORT TERM...KJS
LONG TERM...GF
AVIATION...TGJT