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000
FXUS65 KGJT 220552
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1052 PM MST Mon Jan 21 2019

.UPDATE...
Issued at 845 PM MST Mon Jan 21 2019

Updated to removed expired wind advisory over southeast Utah.
Winds have decreased and will no longer reach advisory criteria.

&&

.SHORT TERM...(Tonight through Tuesday night)
Issued at 237 PM MST Mon Jan 21 2019

Everything looks to be turning out as planned. Snow is being
reported across much of the area along with some gusty surface
winds. The winds are in response to a strong upper level jet as
well as a tightening surface pressure gradient thanks to an
approaching trough. Add to the mix some convection, even a few
rumbles of thunder, and we`ll get the winds we`ve experienced
this afternoon. Most reports have been of gusts in the 25 to 35
mph range but a few spots have reached 40 to 45 mph. Obviously,
this will play havoc for anyone driving with occasional whiteout
(or near whiteout) conditions possible. The good news is that once
the trough moves through, winds will die down quickly. Where`s
the trough? Right now, satellite suggests the upper level trough
is moving across eastern Utah and southwestern Colorado. Surface
analysis shows just about the same thing with southwesterly winds
becoming northwesterly to northerly over, roughly, the same area.
So with that, these gusty winds look to continue through the early
evening hours. Take care, if driving, not only because of the
snowy roadways but also lower visibilities. As far as the storm is
concerned, models continue to show it snowing through tomorrow
morning before easing up. The heaviest snowfall will occur from
now through midnight tonight as the trough pushes through bringing
increased vertical lift while tapping into plenty of divergence
aloft and mid-level instability. The advisories in place still
look good and continue through tomorrow morning.

H7 temps at this hour are in the -4 to -6C range and will drop to
near -12 to -15C by tomorrow. This will translate in a surface
drop of about 10 to 20 degrees...colder up north, less so down
south.

Snow comes to an end Tuesday morning though some lingering showers
are expected over the Divide through about noon. The sun should
make a brief return Tuesday afternoon before more high level
clouds start moving in late Tuesday evening.

.LONG TERM...(Wednesday through Monday)
Issued at 237 PM MST Mon Jan 21 2019

The long term period will be characterized by high pressure to the
west and a deep, deep trough over the eastern U.S. We think it`s
cold here...H7 temps will drop to -22C over the Ohio River Valley
which is MUCH colder than usual for that area. Brrrr. So while
folks out east will be shivering, we`ll be dealing with some
shortwaves dropping down from the northwest. As usual, these waves
will favor the Elkheads, Park Range, Flat Tops, and portions of
the central mountains thanks to favorable orographics. Snow looks
to start around noon Wednesday and continue through noon Thursday.
As of now, snow amounts look to reach advisory levels...6 to 10
inches. Once the wave exits the area, some flurries will persist
until Friday evening when another wave moves in. This wave will be
much quicker and have moved through in about 12 hours so amounts
will also be lighter...maybe 6 inches. After that, no more
precipitation until Monday when another wave moves through. We`ll
be on the tail end of this wave, however, so lift and energy will
be weak as it moves over only bringing minor accumulations.

Enough about the mountains, what about the valleys and areas west.
Fairly boring, actually. Variable cloudiness through much of the
period with inversions remaining in place for the snow covered
valleys keeping temperatures on the colder side of guidance.
Always fun to forecast for.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1046 PM MST Mon Jan 21 2019

Snow showers will continue through about 12Z off and on again
with some breezy conditions at times behind the passing cold front
and trough. Ceilings and visibility will reach ILS breakpoints at
times. Conditions improve after 12Z with some lingering snow
showers over the high terrain through 15Z before skies begin to
scatter out and ceilings rise above ILS breakpoints. VFR
conditions are expected after 15Z Tuesday through the rest of the
day on Tuesday.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 9 AM MST Tuesday for COZ001>005-
     009-010-012-013-017>019.

UT...Winter Weather Advisory until 9 AM MST Tuesday for UTZ023-025-
     028.

&&

$$

UPDATE...CC
SHORT TERM...TGR
LONG TERM...TGR
AVIATION...MDA