Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 230035

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
635 PM MDT Tue Aug 22 2017

Issued at 633 PM MDT Tue Aug 22 2017

Several outflow boundaries have caused some showers,
thunderstorms, and gusty winds near 40 MPH to form in and around
the Grand Valley. Bumped up PoPs for the next few hours to account
for this convection. Rest of the forecast for Colorado and eastern
Utah is capturing the convection well so no changes there.


.SHORT TERM...(Tonight through Wednesday night)
Issued at 140 PM MDT Tue Aug 22 2017

A ridge will remain over the area tonight through Wed. morning with
a shortwave trough rotating over the area from south to north and
through the ridge. A band of mid and high clouds with a bit of
instability will accompany the trough. Thunderstorms are
developing in the sunshine over the mountains ahead of and behind
this cloud band. There is not much shear and CAPE is lacking so
only garden variety thunderstorm are expected.

There will be a period of subsidence behind the shortwave early Wednesday
but by later Wed. afternoon flow aloft will be sandwiched between
an old open wave over CA/NV and the ridge that will have moved to
SE NM and west TX. So late Wed. afternoon and evening may provide
a brief monsoon surge.

.LONG TERM...(Thursday through Tuesday)
Issued at 140 PM MDT Tue Aug 22 2017

Ridging and drier conditions with some subsidence will move in
Thursday as the ridge builds in following a weak trough passing
through Wyoming. Both the EC and GFS show the monsoon plume gets
shoved to the south and east and the surge should be shortlived.

The GFS and EC remain in synch and show strong ridging building
over the Great Basin and most of the western U.S. This produces
dry NW flow aloft over the area through Tuesday with a remnant of
the monsoon plume hanging over SE and South-central CO possibly
clipping the easternmost portion of the San Juan Mountains will
continue Thursday as the ridges is projected to recede to the


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 542 PM MDT Tue Aug 22 2017

A disturbance moving south to north is firing off showers and
thunderstorms along east central Utah and west central Colorado
and will continue to do so over the next few hours. These storms
may bring brief obscurations and reach ILS breakpoints at TAF
sites, with most activity staying in the vicinity of airports.
Showers and thunderstorms are slow moving today, so may impact a
specific spot for 30 to 60 mins before moving off. Gusty winds to
30 kts will be possible from outflow. Activity will taper off
before 06z except for a lingering shower or two.




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