Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 140448

Area Forecast Discussion
National Weather Service Grand Junction CO
1048 PM MDT Mon Aug 13 2018

.SHORT TERM...(Tonight through Tuesday night)
Issued at 255 PM MDT Mon Aug 13 2018

Clockwise rotation associated with high pressure overhead is quite
evident on both radar and satellite this afternoon. Storms firing
along the Continental Divide are drifting from north to south
while activity in northeast Utah and far northwest Colorado are
progressing from west to east. While convection was slow to
develop today, it is now well underway, acting on Precipitable
Water (PWAT) values at or around three quarters of an inch. Gusty
outflow winds, small hail, brief heavy rain, and cloud-to-ground
lightning can be expected with stronger thunderstorms. Activity
will continue this evening with some storms lingering across the
north through the early morning hours as a weak shortwave brushes

The ridge of high pressure will remain in place on Tuesday,
centered in the Four Corners area. Ample moisture will be trapped
under the ridge, above 0.75 inches, and be recycled Tuesday
afternoon for another round of scattered showers and storms. Given
the upper level synoptic pattern, the Continental Divide will be
favored for storms. Elsewhere, expect variable cloudiness and for
temperatures to remain 4 to 8 degrees above normal. Additionally,
flow aloft will keep plenty of smoke in the area for at least the
next several days, though areas that receive a nice shower or two
could get some relief.

.LONG TERM...(Wednesday through Monday)
Issued at 255 PM MDT Mon Aug 13 2018

A rinse-and-repeat weather forecast is in store for eastern Utah
and western Colorado for most of the work week as high pressure
remains in control. Daytime heating each afternoon will work on
residual moisture to fuel scattered convection each day as PWATs
continue to run between 0.75 and 1.00 inches. As has been the
trend over the past few model runs, various ripples in the flow
will enhance precipitation at times, though it`s still hard to
pinpoint the ETA with each. There won`t be much variation with
temperatures with just a degree or two fluctuation each day.

By daybreak Friday an upper level shortwave will push into the
western CONUS, flattening the ridge as it approaches eastern Utah
and western Colorado. Friday evening onwards, extended forecast
models differ in regards to the depth and track of the trough.
The Euro favors a deeper wave with a more southern track while the
GFS is shallower and stays well to the north of our CWA. Needless
to say, given the significant difference in the projected synoptic
pattern, confidence in the forecast from Saturday and beyond is


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1047 PM MDT Mon Aug 13 2018

Showers and thunderstorms have gone to bed this evening, but will
redevelop over higher terrain late Tuesday morning over the higher
terrain. Storms will continue during the afternoon and evening,
mainly over higher terrain with gusty outflow winds of 40 to 50
MPH possibly impacting TAF sites. Smoke will linger over much of
the region, but TAF sites aren`t likely to see visibility drop
below 7SM. VFR CIGS will also prevail at all TAF sites through the
next 24 hours.






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