Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 140854
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
254 AM MDT Sat Oct 14 2017

.SHORT TERM...(Today through Sunday)
Issued at 225 AM MDT Sat Oct 14 2017

As an upper shortwave trough moves through NE UT and NW and
central CO today, its surface cold front will move through the
area. The only sensible weather associated will be over the
northernmost mountains and along the CO and WY border. The more
widespread change will be a 10 to 15 degree drop in temperatures
today and tonight. For tonight and early Sunday morning Freeze
Watches were upgraded to Freeze Warnings for those valleys that
have not yet received a significant freeze. These areas include
the Grand Valley including the Grand Junction vicinity, the Utah
Grand Flat including Arches NP and Moab, and the lower elevations
of SE UT along the Colorado River including Canyonlands and
Natural Bridges.

.LONG TERM...(Sunday night through Friday)
Issued at 225 AM MDT Sat Oct 14 2017

Little to discuss in the extended period as models were consistent
with a dry forecast and near seasonal temperatures through
Thursday. On Monday, flow aloft comes from the northwest on the
leading edge of a shallow transient ridge of high pressure to the
west. The ridge axis shifts overhead Tuesday, then pushes east on
Wednesday resulting in a more zonal flow. A trough off the West
Coast moves onshore Thursday causing flow to shift to the
southwest. Large model discrepancies appear between the GFS and
ECMWF beginning Friday night. The GFS brings a much wetter airmass
to the area beginning late Thursday night suggesting good chances
for precipitation on Friday. In contrast, the 12Z/Friday ECMWF,
though similar in timing, presents a shallower and considerably
drier solution offering little to no chance of precipitation.
Model disparities provide little insight into most probable
outcome and forecast will represent a blend of persistence, GFS
and EC models.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 225 AM MDT Sat Oct 14 2017

VFR conditions will prevail at all the TAF sites for the next 24
hours. A cold front will bring gusty winds today and this evening
across eastern UT and western CO, with scattered showers over the
nigher peaks of northern CO.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Freeze Warning from midnight tonight to 9 AM MDT Sunday for
     COZ006.

UT...Freeze Warning from midnight tonight to 9 AM MDT Sunday for
     UTZ027-029.

&&

$$

SHORT TERM...CC
LONG TERM...NL
AVIATION...CC



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