Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 132351

Area Forecast Discussion
National Weather Service Grand Junction CO
451 PM MST Thu Dec 13 2018

.SHORT TERM...(Tonight through Friday night)
Issued at 204 PM MST Thu Dec 13 2018

Clear skies are in store across western Colorado and eastern Utah
through the short term period. Cool northerly flow aloft combined
with fresh snow cover is keeping daytime temperatures a few
degrees below seasonal today then overnight lows will plummet
tonight with radiational cooling in full swing. Trended toward MET
guidance for tonight`s low, and brought temperatures down a few
degrees along the I-70 corridor and in the Crested Butte-Gunnison
corridor. The only thing that could potentially put a wrench in
the very cold temperatures tonight is that 700mb temperatures will
be warming as a ridge of high pressure builds in from the west.

This ridge will become centered over the Great Basin on Friday.
Rising heights and clear skies will bring the daytime
temperatures a few degrees warmer than today. Temperatures drop a
few degrees Friday night, but southwesterly flow aloft will keep
the lows a few degrees higher compared to tonight.

.LONG TERM...(Saturday through Thursday)
Issued at 204 PM MST Thu Dec 13 2018

Flow aloft becomes zonal on Saturday as a shortwave passing to
the north flattens the ridge of high pressure over the Desert
Southwest. The bulk of this system will stay mostly to the north,
but there still remains a limited possibility of light snow
showers for the northern mountains Saturday morning. Clouds will
increase during the day on Saturday from west to east keeping
overnight lows Saturday night about 10 degrees warmer than Friday
night. The ridge reamplifies on Sunday as a large upper level low
begins to make way across the Pacific Northwest. A trough swings
south across the Mexico-US border Monday night into Tuesday. The
GFS and EC are getting a bit more in-line compared to yesterday`s
runs, but there are still some differences. GFS has a closed low
passing to the south while the EC has an open wave - but either
way most of the moisture will stay to our south with the
possibility of some light snow showers for the Four Corner region
Monday night. Then high pressure returns for the rest of the work
week with temperatures remaining near normal.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 444 PM MST Thu Dec 13 2018

A few high clouds will give way to clear skies this evening with
light, terrain driven winds and VFR conditions prevailing. Some
patchy fog is possible at KGUC but confidence in this occurring is
not high enough to put in the TAF. Something to monitor for later
shifts if this development occurs.




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