Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 201023

Area Forecast Discussion
National Weather Service Grand Junction CO
323 AM MST Tue Nov 20 2018

.SHORT TERM...(Today through Wednesday)
Issued at 322 AM MST Tue Nov 20 2018

The short term period remains quiet and tranquil. The good stuff
happens from Thanksgiving onwards. Until then, high pressure
remains in control bringing plenty of sunny skies though a weak
system to our southwest may bring some high clouds to southern
portions of the CWA. High temperatures will be very similar to
yesterday, if not a degree or two warmer. Wednesday, the ridge
axis will be directly overhead as winds become more south to
southwesterly which will usher in some warmer temperatures, maybe
3 to 5 degrees warmer than today.

.LONG TERM...(Wednesday night through Monday)
Issued at 322 AM MST Tue Nov 20 2018

Complex pattern change will be arriving on Thanksgiving Day with
a series of Pacific storms taking aim on the forecast area. The
first storms arrives Thursday afternoon and continues through
early Friday. Still have some concerns with the amount of moisture
that will be left available after this system tracks across the
Sierra`s and Wasatch Ranges to our west. Second concern will be
with snow levels as system is tapping into warmer southwest air.
And third concern will be with the speed of this wave as 160 kt
speed max rips across the Four Corners Thursday night. System will
be exiting the area by Friday morning, so only looking at a 12 to
18 hour window with high snow levels. Models remaining consistent
with snow amounts in the 3 to 6 inch range, mainly for the higher
peaks with the Central and Southwest Mountains favored.

Next wave arrives on Saturday dropping out of the Pacific
northwest and heads southeast across the Great Basin. This system
will be colder with decelerating speed max working into the area
from the northwest. So basically, the system should be slowing
down as it arrives over our forecast area. Better moisture, colder
temperatures, decent winds aloft and widespread lift from passing
shortwave will get the snow guns working with snow levels dropping
to the lower valley floors. Still too early to determine snow
amounts, but would expect at least moderate accumulations.
Duration also looks to a tad bit longer which will drive those
numbers up even higher. Latest 00Z GFS run throwing a small
wrench into things though as it`s trying to stand the backside jet
up a bit, which could allow the system to dig a bit more before it
arrives. This would send the better moisture and lift from the
northern mountains southward toward the San Juans. With much
uncertainty still in play will keep our Special Weather Statement
(SPS) going for at least another forecast period.

Temperatures will remain on the cool side of normal through the


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 322 AM MST Tue Nov 20 2018

Mostly clear skies and light, variable winds will be the norm
today. VFR conditions remain in place.





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