Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 242157 AAA

Area Forecast Discussion...UPDATED
National Weather Service Grand Junction CO
357 PM MDT Mon Oct 24 2016

Issued at 356 PM MDT Mon Oct 24 2016

Showers and isolated storms forming further east than forecast
indicates so increased chances of pops late this afternoon through
the evening. Also, expanded the coverage a bit further east.


.SHORT TERM...(Tonight through Tuesday night)
Issued at 306 PM MDT Mon Oct 24 2016

The 12Z U/A H5 hand analysis is verifying the deep trough that
models have been advertising off the NOAM left coast. This led to
a long fetch of southwest flow from the subtropics into the Great
Basin. Derived satellite imagery and local RAOB reports are
indicating PWAT running 175-200 percent of (or 4 std dev above)
normal. This plume has been held to the west but is slowly
shifting eastward. Under this moisture band reported precipitation
rates have been 1 to 3 tenths per 6 hours with some isolated
amounts over half an inch. Snow levels out west at or above 10000
feet and figure this is a good indication of what to expect
tonight. Temperatures in the 10-11kft level have made it to the
upper 40s to lower 50s this afternoon and expect this event to
mainly be in the liquid form though some wet/low ratio snow is
definitely likely to fall over some of the mountain roadways. Do
not have enough confidence to issue winter headlines as impacts
appear to be minimal. The strong influx of moisture should also
help keep the more significant accumulations above timberline. We
should see precipitation blossom near the UT/CO border mid to
late evening as ascension in the moisture axis is enhanced by the
arrival of a coupled jet feature. Instability should also be
released by orographics and a mid level fronto feature. Isolated
thunderstorms will be possible through this time and could aid
some high precipitation rates and excess runoff is a possibility.
Snow level in the Western Colorado mountains will be rising
tomorrow morning as drier air works in from the west. Showers
should remain anchored over the hills through the afternoon but
the threat of accumulating snow will be ending. Temperatures will
be cooler behind the trough by some 7 to 12 degrees but still
ending up above normal.

.LONG TERM...(Wednesday through Monday)
Issued at 306 PM MDT Mon Oct 24 2016

Dry and warm conditions move back in for the mid week period as
the ridge rebounds back over the Intermountain West to the
Canadian Rockies. Once again the subtropical jet will usher in
moisture in the upstream portion of the ridge by Friday and an
ejecting wave will bring increasing cloudiness then scattered
precipitation Friday afternoon through Saturday. At the moment
however this system does not appear to be as organized or as moist
but will still be warm with high snow levels. The main piece of
the western trough will be forced inland by Sunday and is forecast
by models to mainly sweep across the northern states and only
brush our region with some lighter precipitation. There is a hint
that beyond this the weather pattern may become a bit more active
for the mid latitudes. Otherwise temperatures remain above
seasonable readings.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1054 AM MDT Mon Oct 24 2016

VFR conditions will prevail through 00z, though mid and high level
clouds will increase over eastern Utah and western Colorado
through the day. Ceilings will gradually lower over the mountains
of northeast UT late this afternoon with showers developing by
sunset. A few showers will be possible over western CO mountains
near sunset as well. Showers will be high based initially so
expect unpredictable outflow winds in the vicinity of buildups.

A disturbance in the southwesterly flow aloft combined with
increased moisture will bring widespread showers to eastern Utah
and western Colorado after 00Z/Tuesday. By 06z Ceiling will lower
to close to or below ILS breakpoints at all TAF sites except KDRO
and KCNY, especially KASE, KEGE and KRIL. Periods of MVFR
VSBY/CIGS are also possible. Conditions will improve from west to
east about 16Z Tuesday.




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