Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 180949

Area Forecast Discussion
National Weather Service Grand Junction CO
349 AM MDT MON JUL 18 2016

.SHORT TERM...(Today through Tuesday)
Issued at 349 AM MDT Mon Jul 18 2016

Water vapor imagery and underlying derived satellite products
suggest the leading edge of monsoon moisture has pushed across the
4 Corners region into our southern CWA early this morning. PWAT on
the 00Z KGJT sounding was sitting just slightly below normal but
expect this to move above normal by the 12Z flight and pushing
into the 90th percentile by this evening as PWAT pushes near an
inch. It is obvious to say shower and thunderstorm chances will
be on the increase today through Tuesday with this moisture in
place. Not so obvious is the triggers beyond orographics that will
be sparking these storms. Speaking of sparks...lightning this
afternoon after the prolonged hot and dry period will be
especially troublesome for fire starts. Initially the storms will
contain more wind than rain and this could lead to rapid fire
spreads. Storms by late this afternoon should be organized enough
that moderate to heavy rainfall become more of a threat along with
the outflow winds. Do expect a downturn in the convection with
sunset but in this flow showers and isolated storms are likely to
continue somewhere in our area overnight. Confidence low on finer
details but with the jet to our northwest and some upper
divergence projected near the CO/UT border overnight...placed the
higher pops in our western CWA. This is a first guess only and
outflow boundaries and mesoscale features will play a bigger role
on nocturnal thunderstorms. Temperatures will cool back to more
normal mid July readings with the added moisture and associated
cloud cover and passing precipitation.

.LONG TERM...(Tuesday Night through Sunday)
Issued at 329 PM MDT Sun Jul 17 2016

High Pressure centered over the High Plains will continue to
drive monsoonal moisture northward across the forecast area
through the end of the week. Expect little change to the daily
forecast with scattered showers and thunderstorms each day, favoring
the afternoon and evening hours. Locally heavy rainfall will be
possible with precipitable water values holding over an inch. The
ridge starts shifting west across New Mexico and into the Four
Corners region by the weekend cutting off the deeper tap of
moisture. So expect a decrease in activity by next weekend and
much drier weather pushing back in by early next week. Both the
GFS and ECMWF advertising a strengthening ridge over the Great
Basin, basically shutting down the round of monsoonal moisture.

Max temps will be cooler throughout the week with higher humidity
values and more cloud cover in place.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 349 AM MDT Mon Jul 18 2016

Moisture is on the increase this morning with mid to high
level cloud cover spreading northward across the region. Ceilings
remain aoa 120kft agl with this initial push but will be lowering
through the later morning and afternoon hours as thunderstorm
activity becomes more organized. Gusty outflow wind threat near
storms this morning and early afternoon will be joined by moderate
to heavy rainfall through the latter hours of the day and may
bring temporary mvfr conditions in rainfall to some forecast
terminal sites. KASE and KTEX should have the highest probability
of this occurring but all sites can not be ruled out. The period
of highest confidence in storm development will be 18/19Z to


.GJT Watches/Warnings/Advisories...
CO...Red Flag Warning from 10 AM this morning to 10 PM MDT this
     evening for COZ200>203-205-207-290>295.

UT...Red Flag Warning from 10 AM this morning to 10 PM MDT this
     evening for UTZ486-487-490-491.



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