Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 191145 AAA

Area Forecast Discussion...UPDATED
National Weather Service Grand Junction CO
545 AM MDT FRI AUG 19 2016

Issued at 542 AM MDT Fri Aug 19 2016

Quick update to the weather grids this morning to add mention of
patchy fog across some of our high valleys in the San Juan
Mountains. The fog is expected to burn off by 9 am MDT.


.SHORT TERM...(Today through Saturday)
Issued at 403 AM MDT Fri Aug 19 2016

West to southwest flow is expected to hold through this morning
with moisture pulling back across the forecast area after a brief
push south last evening. 00z sounding showed precipitable water
values down a bit versus previous days, although models suggest
this will rebound a bit this morning, which is consistent with
current water vapor imagery. Expect one more active afternoon in
the convection department as diurnally driven storms fire around
midday. Storms will again favor the higher terrain early on,
before drifting over the valleys late in the day. Looking upstream
across Idaho, Montana and northern Wyoming we see much cooler
conditions behind a strong front that is expected to drive south
across our area by late this afternoon and evening. This push will
drive the deeper moisture south, promising a drier and slightly
cooler day on Saturday. Winds will be swinging from the west
southwest ahead of the front to the northwest and north behind it.
And storms today will be capable of producing gusty outflow winds
to 40 mph, small hail and brief heavy rainfall. Temperatures will
be running near to slightly above normal with subtle cooling
anticipated behind the front tonight and Saturday.

.LONG TERM...(Saturday Night through Thursday)
Issued at 403 PM MDT Thu Aug 18 2016

Northwest flow is expected to hold in place through late this
weekend with just enough moisture lingering over our southern
zones to keep a slight chance of convection in the forecast.
Otherwise conditions will be dry with below to near normal
overnight temperatures, and near to above daytime temperatures.

Early Monday a closed low over southern California will begin to
lift NE opening to a broad SW-NE trough over the region on
Tuesday. Precipitable water rises to around 0.90 inch or just a
bit above average. Nocturnal storms should be active Monday night
with the developing trough. Storms may be more organized on
Tuesday with increasing shear. Expect less storm coverage on
Wednesday and Thursday in a drier west flow aloft.


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 403 AM MDT Fri Aug 19 2016

VFR conditions will prevail through 18Z across eastern Utah and
western Colorado. Instability driven by rising surface
temperatures will bring another round of scattered showers and
thunderstorms over the mountains from 18Z through 04Z/Saturday.
KRIL, KEGE, KASE and KGUC face a 30 to 40 percent chance of
thunderstorms moving overhead during the time frame mentioned
above. This may result in a brief reduction in CIGS below ILS
breakpoints and strong outflow winds to 40 MPH or higher.


.GJT Watches/Warnings/Advisories...


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