Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 241603
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1003 AM MDT Sun Sep 24 2017

.UPDATE...
Issued at 955 AM MDT Sun Sep 24 2017

Issued Winter Weather Advisory for the eastern Uinta range above
9000 feet. Short-term guidance indicates steady rounds of
precipitation through the afternoon and early evening hours as an
upper-level low spins over northern Utah. While snow ratios will
remain at or below 10:1, snowfall in the 4 to 8 inch range is
possible above 10,000 feet, with up to 3 inches as low as 9000
feet.

UPDATE Issued at 854 AM MDT Sun Sep 24 2017

Issued freeze warnings for several valley zones in western
Colorado for Sunday evening into Monday morning. Guidance/blends
indicate lows at or below freezing in areas with agricultural
interests.

&&

.SHORT TERM...(Today through Monday)
Issued at 332 AM MDT Sun Sep 24 2017

A closed upper low will move from central UTah to the northeast
today and reach southwest Wyoming by about 03z tonight. A large
dry slot will spread over most of the area this afternoon with
the only exception being northeast Utah. This area will be close
to the low center and receive persistent though decreasing
precipitation until about 12z Monday. Monday will be dry and cool.
Snowlevels in the wake of trough passage will remain near 9000
feet.

.LONG TERM...(Monday night through Saturday)
Issued at 332 AM MDT Sun Sep 24 2017

The change of seasons is always a fun time to try and decipher the
models as you get farther out in time. No exception today though the
models do seem in fairly good agreement out through the upcoming
week with respect to the large scale pattern. The large block that
has been in place keeping this trough anchored over the Inter-
Mountain West will let up and allow the pattern to become a more
progressive in the higher latitudes. It is there where the ensemble
relative measure of predictability strongly supports an amplified
ridge setting up across the northern 2/3 of NOAM by late in the
week. The problem area is down here where all the weather will be
taking place. This is because an area of low pressure well be left
behind by the departing trough early in the week. This low will be
cutoff to our southwest as early as Tuesday and become a Rex low as
the above mentioned ridge builds to the north of it around the mid
to late week period. It is this pattern that is makes things
difficult for models to get a handle on. The Cliff Notes are that
this low lingers in our vicinity much of the week into next weekend
and will keep things unsettled...somewhere. The tap to cold air is
not present so snow levels should retreat upward and temperatures
look to slowly moderate through the week. Will watch models
trends and be ready to expect the unexpected.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 332 AM MDT Sun Sep 24 2017

Showers and thunderstorms will continue over northeast UT for much
of today affecting KVEL. ILS cigs area expected under strong
storms along with MVFR cigs and vsbys possible.Areas of low
clouds and fog will produce local IFR conditions in the lower
elevations of southwest CO with KDRO TAF affected until about 17z.
Then conditions will improve and become drier.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Freeze Warning from 10 PM this evening to 9 AM MDT Monday for
     COZ002-005-007-008-021>023.

UT...Winter Weather Advisory until midnight MDT tonight for UTZ023.

&&

$$

UPDATE...MAC
SHORT TERM...CC
LONG TERM...15
AVIATION...CC



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