Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 241738
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1138 AM MDT Sun Mar 24 2024

.KEY MESSAGES...

- Isolated high-based showers and storms are expected through
  this afternoon ahead of the next system.

- Showers become more widespread this evening and Sunday as a
  strong cold front brings temperatures and snow levels down.

- Moderate mountain snow is expected through Monday morning with
  travel impacts over the passes increasing during the overnight
  hours. Rain will fall in the lower valleys with only light
  snow likely in the higher valleys.

- Unsettled weather continues through the coming week with
  additional disturbances bringing scattered showers.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 542 AM MDT Sun Mar 24 2024

A heavy band of clouds is moving north-northeast through
southeastern Utah into northwestern Colorado with widespread showers
in this band. Little rain has been reaching the ground overnight in
the lower valleys with the low-level dry air in the area, but the
atmosphere will saturate to the surface through the morning bringing
welcomed rain to the area. Over the higher elevations, light to
moderate snow showers have delivered a few inches snow overnight
mostly in northeastern Utah and central and northern Colorado
mountains.

Satellite imagery shows the trough over eastern Nevada while the
models look to be running a bit fast with the trough to be already
pushed into Utah. The models also lead satellite imagery by about
three hours placing the low farther south and inland along the
Oregon-California Border where as the imagery puts the low
descending along the central Oregon Coast line. This indicates the
models are struggling to model this complex low pressure system
imposing uncertainty on the timing with this system. The cold front
is stalled just east of the I-15 corridor on the Wasatch Range with
a weak jet aligned south to north directly overhead. As the models
open the low into a wave and accelerate it to the east through the
morning and afternoon, jet support for the front vanishes and the
frontal boundary becomes disorganized as the wave pushes it through
the mountains. With no organized front, the cold air trickles into
the region through the day with no clear active boundary. H700 temps
are currently around -2C, and will drop to about -4C by noon and -6C
this evening. As the cold air of the trough moves in aloft and
diurnal heating today, the CAMs indicate widely scattered showers
popping up through the late morning morning becoming widespread
through the afternoon favoring the Colorado mountains. The trough
axis moves east of the Divide this afternoon with the flow aloft
becoming northwesterly that will favor heavier snow the over the
central mountains and the northern face of the San Juans through the
evening. The northwesterly flow draws drier air into the region that
will significantly diminish shower activity through the overnight
into Monday. Light snow showers will linger through Monday over the
Colorado mountains mostly along the Divide with little more
accumulation

Winter Weather Advisories are in effect for across the higher
elevations of southeastern Utah and Western Colorado for generally
six to 12 inches snow accumulation through Sunday night with locally
more snow up to 18 inches is possible on favorable slopes. Much of
the snow will fall through the afternoon hours, and due to the high
sun angles, the snow on the roads should melt quickly with minimal
impacts from this storm. That being said, periods of winter driving
conditions with icy and snow packed roads are likely though the
mountain areas, especially after sunset. Please exercise appropriate
caution if you`ll be on the roads today.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 542 AM MDT Sun Mar 24 2024

A bit of a lull looks to occur Monday night as the latest storm
system moves east of the Divide into the Plains and Upper Midwest.
Meanwhile the flow still remains unsettled with northwest flow
maintaining some light orographic snowfall over favored ranges as
the deep seated trough carves out over the west. We will see an
uptick in shower activity Tuesday as an embedded shortwave trough
moves through during the afternoon. This period of unsettled weather
will continue through Wednesday afternoon, lingering over the
northern and central Colorado mountains with the backside of the
upper level trough pushing through the area, leaving drier air and
improving conditions in its wake Wednesday evening into Thursday as
a ridge of high pressure builds in behind the trough. Additional
snowfall amounts over the western Colorado mountains and eastern
Uintas Tuesday through Wednesday morning are not overly impressive
with about 1 to 3 inches on average, although the northwest Colorado
mountains appear favored for some locally higher amounts given the
favored northwest orographics and channelized vorticity pushing over
this area. Very light snowfall continues into Wednesday afternoon
but overall, should see improving conditions throughout the day on
Wednesday. Temperatures Tuesday and Wednesday remain around 10
degrees below normal given the unsettled conditions.

This ridge of high pressure moving in by Thursday will not provide
clear skies as moisture still moves inland off the Pacific, dirtying
up the ridge with some high clouds. We will however see some
southwest flow take hold Thursday afternoon through the weekend as
the ridge axis shifts east over the Plains and another low pressure
trough moves inland across the west. Still some uncertainty with
timing of these shortwaves as the trough moves across the west, but
overall, WAA looks to take hold Thursday through the coming weekend
with temperatures taking a turn upwards to near normal values
Thursday and warming up to 4 to 8 degrees above normal by Saturday.
Depending on the timing and placement of these shortwaves, we could
see continued periodic convective afternoon showers each day with
some light orographic snowfall over the northern mountains,
amounting to about 1 to 3 inches or so each 24 hour period, which is
not overly significant with roads remaining wet during the daytime.
The warming trend is the main result of this southwest flow late in
the week. As far as the low pressure trough is concerned, signs
point to a closed low forming at the base over SoCal and moving into
the Desert Southwest and Great Basin this weekend and potentially
impacting our area next Sunday into the following week as we close
out March and move into April, so stay tuned.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1130 AM MDT Sun Mar 24 2024

Large...moist system continues to rotate across eastern Utah and
western Colorado this afternoon. MVFR to LIFR conditions have
been found over SW Colorado up to KHDN where snow and low clouds
are impacting flight travel. Expect much of the central CWA to
fill in during the afternoon as things become more unstable and
the main circulation lifts out of the 4 Corners to the central
Rockies. An extended period of widespread MVFR to LIFR
conditions are forecast through the late afternoon and early
morning hours. Northerly flow in the wake of the main
circulation will continue to impact KTEX and KASE with
orographic low clouds and likely snow past sunrise. Lightning
from isolated storms and gusty winds will also be threat through
the evening.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory until midnight MDT tonight for COZ003-
     017.
     Winter Weather Advisory until 6 AM MDT Monday for COZ004-009-
     010-012-013-018-019.
UT...Winter Weather Advisory until midnight MDT tonight for UTZ028.

&&

$$

SHORT TERM...DB
LONG TERM...MDA
AVIATION...TGJT


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