Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 121719
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1019 AM MST Tue Dec 12 2017

.SHORT TERM...(Today through Wednesday)
Issued at 344 AM MST Tue Dec 12 2017

High amplitude upper level pattern remains in place across NOAM with
a Western States ridge transitioning to a deep trough across the
East. Water vapor imagery is showing a well defined system moving
onto the Left Coast of British Columbia. This is being pushed east
by a stronger piece of the Polar jet which is approaching upstream
from the C.Pacific. This lead wave will have little impact to our
region but it pull along some high level moisture over the ridge
going into Wednesday. We will see high level cloudiness thickening
on our northern border around sunrise tomorrow then drifting
southward through the morning. As previously mentioned cross
sections still show this moisture well above the mountain tops and
do not expect much more than flurries over the very high divide
peaks through sunset. This wave will push mid level temperatures
down a bit by tomorrow afternoon so slightly cooler in the
northern CWA due to this and some cloud cover. Otherwise
temperatures will be similar to days past the next few afternoons.

.LONG TERM...(Wednesday night through Monday)
Issued at 344 AM MST Tue Dec 12 2017

The nose of the upper jet arrives Wednesday evening with another
batch of moisture and channelized energy. This weak ascent should
be enough to produce some light snow showers over the northern
and central mountains of Colorado during the overnight hours
before clearing starts on Thursday. Snow amounts like moisture
look limited to the higher terrain with amounts generally in the 1
to 2 inch range above 9500 feet. This jet diving into the Plains
will basically relocate the ridge axis east of the Left Coast and
set the stage for energy and moisture to have a better trajectory
into the Great Basin. A portion of the western ridge will be bent
into the Rockies late in the week by the arrival of the next
system arriving to the PacNW. This system provides some hope to
the recent dry spell and could spread some snow across most of our
mountains outside of SE.Utah late Saturday into early Sunday.
Fairly good dynamics with the storm which should bring some
precipitation down to the lower elevations but will need a few
more runs to get this dialed in. The ridge will have little time
to recover out west before a much more potent system drops out of
the higher latitudes. This system could be more of a weather maker
to the West by the middle to latter part of next week so stay
tuned.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1019 AM MST Tue Dec 12 2017

Widespread VFR conditions will continue to prevail across the
region as a strong upper level ridge remains overhead. Winds will
be light and variable through the next 24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...15
LONG TERM...15
AVIATION...MMS



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