Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 180357 AAA

Area Forecast Discussion...UPDATED
National Weather Service Grand Junction CO
957 PM MDT SUN JUL 17 2016

Issued at 957 PM MDT Sun Jul 17 2016

Cancelled the Red Flag Warning that was in effect until midnight
tonight as winds have lessened with relative humidity values
climbing across the northern zones and thunderstorms have been
very isolated late today with the threat diminishing tonight.

However, due to the very limited thunderstorm coverage today and
more widespread thunderstorm coverage expected Monday with more
sufficient moisture moving into the region, decided to upgrade the
Fire Weather Watch to a Red Flag Warning for Monday. Added the
remaining northern fire weather zones that were not in the watch
as PW values of 1 inch are forecasted to extend as far north as
the Wyoming border increasing the threat for thunderstorms and dry
lightning. Thunderstorms look to develop earlier than expected so
shifted the start time earlier in the day to start at 10 am MDT to
match with WFO Salt Lake City.


.SHORT TERM...(This evening through Monday night)
Issued at 329 PM MDT Sun Jul 17 2016

Moisture continues to slowly invade the region from the south
this afternoon with a few light echoes showing up on radar.
Hi-res models not all that excited about the potential for more
than isolated activity through this evening with storms focused
on the higher terrain. Still could see some gusty and erratic
outflow winds and lightning will remain a concern as little to
no rainfall is expected this evening from storms that do form.

Deeper plume of moisture arrives near the Four Corners by morning
with precipitable water values quickly climbing to over an
inch...peaking by late Monday afternoon. Weak ripples embedded
within the flow...combined with daytime heating and forcing on
south facing slopes will trigger more widespread convection on
Monday with storms moving from south to north. Storm motion will
be a tad bit faster for this time of year with gusty outflow
winds a continued concern, especially early on in the day and
along the northern edge of the deeper moisture plume.

Storms continue through Monday evening with a few hanging on
through the night as we often see in these deeper pushes, so
will not shut pops off completely Monday night.

After several hot days, temperatures will be dropping with the
trade-off being higher relative humidity and warmer overnight
lows. Expect max temps to fall in line with current guidance
which will place much of the forecast area near to slightly below
seasonal norms for the next few days.

.LONG TERM...(Tuesday 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 00Z TAFS through 00Z Monday evening)
Issued at 434 PM MDT Sun Jul 17 2016

Isolated showers will continue over the higher terrain this
evening with little to no rainfall. Minimal impact expected at
TAF sites aside from brief periods of gusty winds of 20 to 30 mph
through 03z. VFR conditions will prevail through the overnight.
Showers and thunderstorms will increase from the south Monday
morning after 12z with better chance of wetting rain after 21z
with gusty outflow winds and lightning the primary threats.


Issued at 957 PM MDT Sun Jul 17 2016

Moisture continues to lift north towards the Four Corners region
this evening. This moisture is expected drive north and east
across most of our forecast area overnight and through the day on
Monday. This will bring an increased potential for thunderstorms
to the area, beginning this evening with activity picking up
during the day on Monday. Storms will initially be high based and
dry, producing gusty and erratic outflow winds and lightning with
little to no rainfall expected. With the forecast area coming off
the recent hot and dry stretch and very isolated thunderstorm
coverage late today, decided to upgrade the Fire Weather Watch
for Monday to a Red Flag Warning as many areas will see more
widespread thunderstorms with dry lightning potential. The
potential for wetting rains will increase late in the day on
Monday, especially over the San Juan Mountains and across the
Abajo and La Sal Mountains in southeast Utah. With humidity values
climbing and storms becoming more efficient at producing rainfall,
expect the recent critical fire weather conditions to start easing
by late Monday night and Tuesday, although gusty outflow winds and
lightning will continue to be a threat near any thunderstorms.


.GJT Watches/Warnings/Advisories...
CO...Red Flag Warning from 10 AM to 10 PM MDT Monday for COZ200>203-

UT...Red Flag Warning from 10 AM to 10 PM MDT Monday for UTZ486-487-



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