Area Forecast Discussion
Issued by NWS Grand Junction, CO

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438
FXUS65 KGJT 172349
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
449 PM MST Fri Nov 17 2017

.SHORT TERM...(Tonight through Saturday night)
Issued at 233 PM MST Fri Nov 17 2017

Complicated storm system continues to impact the region this
afternoon with scattered showers and a few thunderstorms
continuing. Unseasonably warm temperatures remain in place across
the southern two-thirds of the forecast area with a strong cold
front poised to drop south this evening. Grand Junction was within
a degree of tying the record high for today (69 degrees) and could
still hit it by 3 pm before we start turning the dial back down.

The front passed through KVEL and KCAG early this afternoon. As of
2 pm MST, KEEO was sitting at 60 degrees F while KCAG was down to
35 with rain transitioning over to snow. Expect a rapid drop in
temps through the evening hours with gusty west winds shifting to
the northwest and north behind the front. The warm temperatures
and high snow levels (generally above 9k) have limited snowfall
accumulations thus far. However, remote sensors across the West
Elks near Crested Butte showing new snow amounts from 10 to 15
inches using basic 10 to 1 or even 8 to 1 ratios, which line up
with readings from our weather observer in Gothic. An additional
3-6 inches with isolated higher amounts near stronger convective
cells looks reasonable through this evening.

The cold front will arrive in the Vail Pass region between 4 and
6 pm, bringing a burst of heavier snowfall along with gusty winds.
This will create significant impacts to travel for a few hours,
with more stratiform and lighter snowfall setting up after 8 pm
that lingers through midnight. Bands will continue shifting south
through the night with snow levels dropping to the valley floors
as the front passes.

No changes to current highlights as we still anticipate
significant impacts to travel over our higher passes as the cold
front passes and snow levels drop. Flash freezing of water on
roadways could occur in areas where rain has been falling with
temps rapidly dropping to freezing. The gusty west winds will be
shifting to the northwest with speeds reaching advisory levels
across most of the lower valleys. The winds ease within an hour or
two after frontal passage.

This storm will be exiting by sunrise, with dry, but much cooler
weather settling in under building high pressure for the remainder
of the weekend. After several days/weeks of above normal temps,
we will be receiving a day or two of "below" normal temps Saturday
and Sunday.

.LONG TERM...(Sunday through Friday)
Issued at 233 PM MST Fri Nov 17 2017

Flat, transitory high pressure will shuffle east Sunday and
Monday with slowly moderating temperatures. Next potential weather
maker arrives Monday night and Tuesday as a filling wave slides
down eastern edge of building west coast ridge. Expect a brief
period of rain and snow late Monday night into Tuesday morning
with main impacts over the northern and central mountains. High
pressure regains control late Tuesday and looks to stick around
the Friday with dry and seasonal conditions expected.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 449 PM MST Fri Nov 17 2017

Ongoing strong weather system across the region will impact TAF
sites over the next 6 to 12 hours. The cold front is pushing
through I-70, with convection developing along its edge. Some VCTS
will be present, but cloud to ground lightning strikes are few and
far between. The front will continue southward toward KASE, KMTJ,
KTEX, and KDRO this evening bringing gusty winds and precip.
Visbilities in some spots could be pushing airfield mins at times,
but confidence is low on exact timing of these convective bursts
which will lower visibility.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Wind Advisory until 9 PM MST this evening for COZ001-002-006>008-
     011-014.

     Winter Weather Advisory until 5 AM MST Saturday for COZ018-019.

     Winter Storm Warning until 5 AM MST Saturday for COZ004-009-010-
     012-013.

UT...Wind Advisory until 9 PM MST this evening for UTZ022-027-029.

&&

$$

SHORT TERM...JDC
LONG TERM...JDC
AVIATION...JAM



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