Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 221745

Area Forecast Discussion
National Weather Service Grand Junction CO
1145 AM MDT FRI JUL 22 2016

Updated aviation section

.SHORT TERM...(Today through Saturday)
Issued at 326 AM MDT Fri Jul 22 2016

The arrival of low pressure to the left coast of central NOAM will
signal a change in the pattern across the west beginning today.
PWAT on the sounding was near 1.2 inches which put us in record
territory for the latter half of July. Ground based measurements
show this has dropped off to just over an inch this
morning...still sufficient for another round of heavy rain
producing thunderstorms today. Embedded waves are quite hard to
pick out this time of morning with the more apparent lift over the
far desert SW and over the panhandle of UT where large scale
ascent from upper jet support exists. There is an apparent wave
laying across the 4 Corners region which is firing some nocturnal
isolated storms. This feature will elongate over our southern cwa
this afternoon and most likely lead to the better storm coverage.
Farther north it appears storms may be more rooted to the terrain
except in the far northwest where storms will have some upper
support from the jet mentioned above. Corfidi vectors and mid
level wind/wind diffluence suggest slow moving and possibly
backward propagating storms again in southeast Utah and southwest
Colorado. Localized flash flooding is possible but again not
confident again this morning for widespread problems to warrant
issuance of a watch. The westerly flow aloft will be pushing the
main monsoonal plume to the east and models suggest PWAT will be
cut nearly in half by tomorrow as drier air moves in. Storms
should be orographically based and favor the eastern mountains.
Temperatures should top out near normal today and begin an upward
trend tomorrow.

.LONG TERM...(Saturday night through Thursday)
Issued at 326 AM MDT Fri Jul 22 2016

The Pacific NW upper Low ejects through the northern Rockies
while the subtropical High also expands across the southern tier
of states into the SE Pacific. The flow across the north veers to
dry west. The latest forecasted afternoon winds do not reach
critical fire weather criteria. For the southern forecast area
marginal moisture lingers for isolated to scattered late-day
storms favoring the Abajo and San Juan Mountains.

Daytime temperatures will be 5-10 degrees above normal across the
north and central zones, 0-5 degrees above across the south.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1145 AM MDT Fri Jul 22 2016

Thunderstorm activity has begun to initiate over the San Juans,
Grand Mesa, La Sal Mtns, and the Uncompahgre Plateau. Expecting
activity to continue and expand through the afternoon in these
areas. KTEX and KASE remain the highest at threat for
thunderstorms to reach within 5nm. There is potential for
reduction of visibility due to stronger storms but have left out
of TAFs for now. Drier air will move in this evening, allowing for
clearing to occur around sunset tonight.


.GJT Watches/Warnings/Advisories...


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