Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 102318
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
418 PM MST Tue Jan 10 2017

.SHORT TERM...(Tonight through Wednesday night)
Issued at 331 PM MST Tue Jan 10 2017

After yesterday`s nasty weather day partly sunny skies and warmer
temperatures were observed in Grand Junction. These partly cloudy
skies allowed the afternoon high temperature in Grand Junction to
rise to 36 degrees. Hopefully, these conditions allowed for some
improving roadway and side walk conditions. Elsewhere around the
forecast area temperatures are running between 3 and 5 degrees
warmer than 24 hours ago.

The current satellite IR image is showing high clouds streaming
into the area ahead of the next weather system which is expected
to bring additional snow fall to the mountains and higher
elevation valleys beginning tonight. KGJX doppler radar is already
showing snow over southeastern Utah, however local observations
are indicating that this snow is not reaching the ground quite
yet.

Warm air advection ahead of the approaching storm system will lift
snow levels to 6500 to 7500 feet. Initially, snow is expected to
accumulate over the northern and central Colorado mountains with
some of the greatest accumulations occurring overnight tonight
into tomorrow morning. Snow levels will gradually lower tomorrow
allowing snow to reach lower elevations. The higher elevation
valleys will also pick up a quick 3 to 6 inches of new snow
overnight as well. Therefore we have issued Winter Storm Warnings
for the northern and central mountain zones and advisories for
numerous areas. For more information please see the winter storm
warning and advisory message DENWSWGJT or check our homepage for
the latest watches, warnings and advisories.

.LONG TERM...(Thursday through Tuesday)
Issued at 331 PM MST Tue Jan 10 2017

The current satellite water vapor image is showing a trough of low
pressure pushing into the West Coast with another storm system
centered approximately 950 miles off of the Oregon coast. In
addition the satellite and GPS derived total blended precipitable
water image is showing yet another atmospheric river pushing into
the west coast. Precipitable water values associated with this
atmospheric river over the Eastern Pacific and California coast
are ranging between 1.1 and 1.3 inches, which is substantial.

The 1200Z ECMWF and GFS20 have initialized well with the these
synoptic weather features and remain in good agreement through
next Tuesday. Both of these forecast models show the trough of low
pressure pushing into the west coast interacting with the
atmospheric river resulting in another round of snow tonight into
Thursday morning. A short break in the winter weather action is
anticipated Wednesday morning before the second storm system
pushes into California steering yet more moisture into our area
resulting in a reinforcing shot of snow Thursday afternoon into
Saturday. Most likely this second shot of heavy snow will bring
snow to the lower elevations than tonight`s system.

The latest model runs are showing this storm system moving down
the California coast into Mexico by Saturday. This scenario will
place southern portions of our CWA in wrap flow resulting in
additional snow for the San Juans on Saturday and Sunday. Please
be sure to monitor the forecast for frequent updates as this storm
system unfolds.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 924 AM MST Tue Jan 10 2017

Some locally dense fog is expected through the late morning hours
around KGJT and Craig area in northwest Colorado. This fog is
expected to burn off after 18Z with some patchy fog lingering
through 19Z. Some light snow will continue over the western
Colorado mountains as well through the afternoon with improving
conditions over the valley locations. Mountain TAF sites such as
KASE, KEGE and KTEX will have periods of cigs below ILS
breakpoints today as mountains remain obscured. Clouds will
increase again this evening ahead of the next disturbance with
cigs lowering below ILS breakpoints at most TAF sites. Snowfall
will begin again over the mountains early Wednesday morning.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory from 3 AM Wednesday to midnight MST
     Wednesday night for COZ001>003-017>019.

     Winter Storm Warning from 9 PM this evening to 9 AM MST Thursday
     for COZ004-009-010-012-013.

     Winter Weather Advisory from 9 PM this evening to 9 AM MST
     Thursday for COZ005.

UT...Winter Weather Advisory from 3 AM Wednesday to midnight MST
     Wednesday night for UTZ023-025-028.

&&

$$

SHORT TERM...Larry
LONG TERM...Larry
AVIATION...MDA



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