Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 120828

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
228 AM MDT Thu Oct 12 2017

.SHORT TERM...(Today through Friday)
Issued at 227 AM MDT Thu Oct 12 2017

Strong upper level jet rounding the base of longwave trough over
the Pacific Northwest and Northern Rockies will be nudging into
our area this afternoon and tonight. Surface gradients will also
be tightening up and with strong jet aloft and battle between cool
and warm air in place, expected locally breezy conditions in the
valleys this afternoon with windy weather up in the hills. The
breezy to winds conditions will persist through Friday before the
main trough tightens up and kicks out across the area. More on
that in the long term discussion below. Expect periods of mid and
high level clouds to pass through the area over the next 36 hours
with temperatures running right around normal for this time of the

.LONG TERM...(Friday night through Wednesday)
Issued at 227 AM MDT Thu Oct 12 2017

The pressure gradient remains tight Friday night allowing winds
to remain elevated. The upper level trough and associated cold
front drops into eastern Utah and western Colorado Saturday
morning, bringing some precipitation (likely in the form of snow) to
the higher terrain of northeast Utah and northwest Colorado.
Precipitable water values are only a quarter of an inch at best,
so it will be very unlikely that the lower valleys will see any
precipitation. The most noticeable weather change will be the
shift from westerly to northerly winds with this frontal passage,
dropping temperatures by about 10 degrees on the whole. High
pressure builds back into the Desert Southwest and southern
Rockies early next week. By the end of the work week, models
diverge, but do agree on winds increasing toward the end of the


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 227 AM MDT Thu Oct 12 2017

Increasing southwesterly winds will be the primary concern with
aviation across eastern Utah and western Colorado through tonight.
An upper level jet will be moving into the region, bringing
stronger southwest winds into the area. Expect pockets of LLWS,
especially near the steeper valley TAF sites such as KASE and
KTEX. During the peak heating of the day (after 18z) the stronger
winds will mix down to the surface easing the potential for wind
shear, although inversions redevelop around sunset with LLWS
returning to most sites. Otherwise, VFR conditions expected with
mostly clear conditions.




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