Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 151655
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
955 AM MST Fri Dec 15 2017

.SHORT TERM...(Today through Saturday)
Issued at 400 AM MST Fri Dec 15 2017

Quiet weather will be the rule across eastern Utah and western
Colorado through the next 24 hours. Cirrus moving through the
ridge will drift overhead during the day, increasing in coverage
tonight as an approaching Pacific trough breaks down the ridge.

The approaching system will drive a cold front to the Uinta
Mountains by sunrise Saturday where it will stall as the trough
splits, sending energy southward toward the Las Vegas area. This
leaves all but a portion of northeast Utah in the warm, dry
sector southeast of the front. Dynamics and moisture at the
frontal interface will bring a chance of snow showers to the
eastern Uinta Mountains Saturday morning with better chances
Saturday afternoon. Clouds increase elsewhere, but precipitation
will hold off until the later periods.

Temperatures will moderate in the mountains and north today with
little change elsewhere. Increasing clouds tonight will limit
cooling so expect overnight lows will be less cold on Saturday
morning. Clouds continue to increase on Saturday which will hamper
warming during the afternoon. Of course, the eastern Uinta
Mountains will also feel the impact of the incursion of cold air
behind the cold front described previously.

.LONG TERM...(Saturday night through Thursday)
Issued at 400 AM MST Fri Dec 15 2017

As the next Pacific trough approaches the region on Saturday,
southwesterly flow will increase over the area as this system
begins to take a southern track in response to the progression of
the upper level jet. The Eastern Uinta Mountains look to have the
best potential for any snow showers on Saturday night before the
better energy and moisture associated with this system dives south
of the Four Corners region. With this track the higher peaks of
the San Juans could see a quick shot of snow throughout the day
on Sunday before this disturbance lifts into the southern Plains.

Northwest flow aloft will set up across the region in the wake of
this system on Monday and continuing through Tuesday. As the
previous forecaster mentioned, some light orographic snow showers
may persist over the northern Colorado mountains during this time
frame in the favorable flow. Otherwise, skies will generally clear
and temperatures will moderate.

The next, more substantial trough of low pressure will drop down
into the western CONUS around the midweek point. Models are in
much better agreement compared to this time yesterday in showing
this open wave move into eastern Utah and western Colorado
Wednesday evening with isolated to scattered showers of rain and
snow developing with the progression of an associated cold front.
700mb temperatures are impressive with this system, bottoming out
to as low as -10 to -18 degrees C throughout the region on
Thursday. The arrival of this cold air mass could push snow levels
down to valley floors, so that will definitely be something we
will continue to monitor over the coming days.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 954 AM MST Fri Dec 15 2017

Expect VFR conditions with CIGS above ILS breakpoints at all TAF
sites through the next 24 hours. Winds will generally be light and
terrain driven.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...NL
LONG TERM...MMS
AVIATION...CC



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