Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 182104

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
304 PM MDT Mon Sep 18 2017

.SHORT TERM...(Tonight through Tuesday night)
Issued at 127 PM MDT Mon Sep 18 2017

A broad trough is approaching from the west with dry southwest
flow aloft overhead. Winds aloft and at the surface will increase
as the trough approaches. The broad trough axis will skim past the
northern CO and UT borders from 18z to 00z tomorrow with the first
embedded shortwave trough helping drag a weak cold front across
the northern state border areas. A 100 kt jet will travel through
souther Wyoming Tuesday afternoon and night.

The increasing winds and relatively low humidity will increase
fire concerns. Please see the fire weather section below. In
general the humidity will remain barely wetter than critical fire
weather criteria Tuesday afternoon everywhere except extreme SW
CO and SE UT.

.LONG TERM...(Wednesday through Monday)
Issued at 127 PM MDT Mon Sep 18 2017

The jet axis remains over Wyoming Wednesday through Thursday and
starts to pivot to take on a more southwesterly orientation
Thursday. Thursday night a strengthening shortwave trough dives
down the west side of the main low, deepening the low
dramatically. The main jet axis shifts over to Utah and increases
to a solid 120 kts with 100 kts of jet covering most of eastern UT
and into NW Colorado. A shortwave trough will ride up the east
side of the main trough over southwestern and west-central CO
Thursday night and Friday and may produce a band of precipitation
oriented south to north over southwest and central CO with the
axis of the band extended from about Durango to east of

Following that, the trough slowly moves through the Great Basin
and for the most part a dry slot will reside over the forecast
area. But, moisture begins to be tapped from the south and this
gradually fills the eastern part of the trough and spread over the
forecast area from the north and east toward the southwest. The
main trough is projected to pass over the forecast area Monday.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 127 PM MDT Mon Sep 18 2017

VFR conditions will prevail for the next 24 hours. Mid and High
level clouds will move in from the west Tuesday and southwest
winds will increase as a storm approaches. The winds will cause
widespread mechanical turbulence over and to the lee of


Issued at 127 PM MDT Mon Sep 18 2017

Surface winds will increase across the area Tuesday, with
strongest winds in the northern two thirds of the area. A broad
and strong trough with a series of embedded shortwave troughs will
approach Tuesday and move over the area through the week. All but
the most southern zones should remain too moist with RH not
reaching criteria. Utah zone 291 south of Blanding will have
critical weather conditions but the fuels are not critically dry.
CO zone 207 has critical fuels but it doesn`t look like the
weather will reach criteria long enough for a large enough area to
require a red flag warning.




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