Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 110527

Area Forecast Discussion
National Weather Service Grand Junction CO
1027 PM MST Mon Dec 10 2018

.SHORT TERM...(Tonight through Tuesday night)
Issued at 200 PM MST Mon Dec 10 2018

Dry weather and light westerly flow continue over eastern Utah and
western Colorado today. A weak trough, currently located inland
across the northern Great Basin, is slowly working eastward this
afternoon. Ahead of this system, higher clouds will continue to
spread over the western slope this evening and overnight. Short-
term forecast guidance has continued to trend downward regarding
chances for precipitation with this system on Tuesday morning and
afternoon. In today`s package, we have trended PoP chances down
below 15% across much of the central mountains. Some quick
flurries may still reach the ground across the San Juans as well
as the northern mountains, however any accumulations should remain
around an inch or less.

Westerly flow and dry air move in by Tuesday evening and
overnight. Temperatures do not drop all that much behind this
system and not much change was made in this forecast package. Our
next storm system will begin to spread some high clouds in across
northern Utah and Colorado early on Wednesday morning.

.LONG TERM...(Wednesday through Monday)
Issued at 200 PM MST Mon Dec 10 2018

The primary concern in the long-term forecast centers around the
next storm system set to arrive on Wednesday. Forecast guidance
has come into better agreement this morning in today`s 12z model
cycle. By late-morning on Wednesday, light snow will overspread
the eastern Uinta mountains. The Park and Flat Top mountain
ranges will see snow by mid-afternoon, and by sunset, all mountain
ranges will see accumulations. The GFS and NAM still indicate a
bit more moisture than the ECMWF from Wednesday through the end of
the storm on Thursday morning. Still, QPF totals from all models
are within a tenth of an inch or two in most locations, except for
the San Juans where the ECMWF is drier. Have leaned a bit more
toward the NAM and GFS today, given the ECMWF`s trend southward.
Any winter weather headlines would be limited to lower-end
advisories, however confidence in snow accumulations above 6
inches in the mountains is not high enough at this time. Forecast
soundings do not indicate much saturation in the valleys with this
next system. A hundredth here and there across the lower Yampa
Valley, Grand Valley, and Montrose areas is all that should be
expected, which would translate to maybe a dusting to a coating of
snow given 700mb temperatures near -10 degrees.

Dry weather moves in by Thursday morning as this storm system
moves east. Weak ridging and dry conditions will rule the forecast
from Thursday through Saturday morning, and temperatures will
rebound to near average levels. By the weekend, forecast guidance
diverges with the GFS bringing in another weak trough on Saturday
and the ECMWF keeping this trough further to the north. In fact,
the dry trend on the ECMWF lasts all the way through Monday
evening. After a rather active start to our winter season, a drier
pattern is in the works through the middle of December.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1027 PM MST Mon Dec 10 2018

Clouds will remain over the area tonight as a disturbance
approaches from the northwest. This system is expected to bring
some light snow to the mountains, mainly the San Juan`s Tuesday
afternoon with very little chance of snow impacting TAF sites.
Therefore, expect VFR conditions with light winds through the next
24 hours.






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