769
FXUS65 KGJT 221143
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
443 AM MST Fri Nov 22 2024

.KEY MESSAGES...

- More sunshine on tap with some high clouds expected this
  afternoon. Warm temperatures continue.

- Snow returns early Sunday night through Monday morning as an
  Atmospheric River sets up across the region.

- A stronger, more prolonged surge of moisture moves in late
  Monday night bringing significant snowfall to most mountains
  in UT and CO. This snow may persist through late Wednesday
  night/early Thursday morning.

- If you`re planning on travelling during Thanksgiving week,
  especially over any mountain passes, please pay close
  attention to the latest forecasts as amounts and timing may
  change over the coming days.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 203 AM MST Fri Nov 22 2024

Primarily dry conditions are expected through most of the short
term while an upper-level ridge continues to propagate through
our region. Skies will be mostly sunny with high and mid clouds
present. Starting Saturday night there is a chance of rain and
snow in the northern portion of our CWA as some moisture streams
in from the southwest, and a jet streak associated with the
upper-level trough, that has been impacting the West Coast,
moves towards our region. Surface wind speeds are expected to
increase Saturday as the jet streak approaches, with gusts above
20 mph possible in some areas.

High and low temperatures will continue to rise through most of the
short term due to warm air advection and may be 5-10 degrees above
normal. However, a cold front will be approaching our region
Saturday night into Sunday, which will drop temperatures going into
the upcoming week as flow becomes more northerly.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 203 AM MST Fri Nov 22 2024

The long term period has remained relatively unchanged over the
last few model runs. Guidance continues to show a long period
of unsettled weather for next week thanks to an active
atmospheric river. Before that occurs, we can expect some
lighter snow as the initial surge of moisture from an
atmospheric river starts to decay. Accompanying this moisture
will be a surface cold front that will be approaching the area
Saturday night into Sunday. Ahead of the front, some gusty
winds will materialize and by evening and overnight, snow will
fall over the eastern Uintas, Flat Tops, and northern and
central mountains. As of now, advisory level snowfall is
expected with this first push or around 4 to 8 inches of new
snow.

Models agree that by Monday morning a quick transitory ridge
will push through bringing an end to snow though a few showers
may persist. This break will last for about 12 to 24 hours
before things start ramping up. An area of low pressure just off
the PacNW coast will open up and start dropping southeastward.
As this occurs, the jet stream will set up from California all
the way to the Plains...moving directly over southern UT and
CO...in a zonal, west to east flow. The location of the jet will
allow moisture to start, and continue, streaming into the
desert southwest through late Wednesday night/early Thursday
morning. PWATs are expected to reach 200 to 250% of normal
thanks to this AR and the end result will be some decent
snowfall through that period. As the trough approaches, lift
will start increasing thanks to divergence aloft from the jet,
another shot of cold air from the next cold front, and favorable
orographics. Snow will start overspreading the San Juans Tuesday
morning and the rest of the higher terrain as the upper level
trough approaches. If models remain on track, this will be a
prolonged event with 1 to 2 feet of snow possible for the
mountains of Colorado and La Sals and Abajos in Utah. The
northern valleys will likely see a few inches of snow as will
the I-70 corridor from Glenwood Springs eastward.

Important to mention that previous runs did start pushing the
trajectory of deepest moisture to the south and that trend
continues. The NBM is still keeping those high snowfall amounts
for all CO mountains though so wouldn`t be surprised to see
amounts lower north of the I-70 corridor as hi-res guidance
starts getting into the forecast mix.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 427 AM MST Fri Nov 22 2024

Many sites will have scattered to broken high cloud coverage
during the forecast period. However, winds will be light and VFR
conditions are expected to prevail.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

SHORT TERM...GF
LONG TERM...TGR
AVIATION...TGJT