Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 162241

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
341 PM MST Thu Nov 16 2017

.SHORT TERM...(Tonight through Friday night)
Issued at 341 PM MST Thu Nov 16 2017

Significant moisture is on the way as an atmospheric river is moving
into central California starting today. This fetch of moisture
extends past 159 degrees west (longitude of Hawaii), signaling a
very strong source of moisture which will bring unseasonable
moisture to the region for a short period of time while the upper
level jet pushes it into Utah and Colorado. Windy conditions have
already developed at higher terrain, and these winds will increase
further on Friday as the 150 kt ULJ slings across Utah and Colorado.
Because of this system being relatively warm for a winter storm, we
are anticipating big snow amounts above 10000 feet, but a quick drop
off to no accumulation as one decreases in elevation.

Precipitation will generally begin as snow above 9500 feet tonight,
with rain/snow mix possible as low as 8000 feet in convective
showers. The cold front associated with this system does not advect
cooler air into extreme northwestern Colorado until Friday
afternoon, across the I-70 corridor until the evening hours, and
southward into the San Juans until late Friday as well. As the cold
front progresses northwest to southeast through eastern Utah and
western Colorado, the snow level will drop, but very dry air will
also entrain into the region. This is expected to shut precipitation
off quickly overnight Friday night into Saturday.
Models are hinting at a possible Gorge effect south of Montrose in
NNW flow Friday night lingering into the morning hours. 700mb flow
seems a little light for this effect, but it is a possibility.

.LONG TERM...(Saturday through Thursday)
Issued at 341 PM MST Thu Nov 16 2017

By Saturday morning, dry northerly flow should shut down all
precipitation as high pressure moves back into the Great Basin.
Cool seasonable temperatures will persist for a couple of days
behind the cold front, especially with weak inversions developing
overnight. A weak weather disturbance is expected to move into
northern Utah and Colorado Monday evening and early Tuesday...riding
over the high pressure. Confidence is low to moderate on this
feature because of some waffling between forecast model runs. Dry
weather returns midweek before the next possible weather disturbance
at the end of the work week from the west.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1100 AM MST Thu Nov 16 2017

Breezy pre-frontal winds will sweep over eastern Utah and western
Colorado this afternoon/evening ahead of an approaching Pacific
storm. Meanwhile, clouds will be increasing over the area but CIGS
aren`t expected to lower below ILS breakpoints at KRIL, KEGE,
KASE, KGUC and KTEX until after midnight. Later tonight showers
are expected to impact KEGE, KASE, KTEX and KGUC resulting MVFR
visibility with brief IFR visibility and MVFR ceilings possible.
Winds will remain blustery in the higher elevation airports,
especially when combined with showers.


CO...Winter Weather Advisory from 11 PM this evening to 5 AM MST
     Saturday for COZ018-019.

     Winter Storm Warning from 11 PM this evening to 5 AM MST
     Saturday for COZ004-009-010-012-013.



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