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Area forecast discussion 
National Weather Service Grand Junction Colorado
407 am MST Monday Dec 22 2014

Short term...(today through tuesday)
issued at 405 am MST Monday Dec 22 2014

A complicated winter storm continues to evolve over the region.
There is strong confidence in the large scale details. Deep
moisture continues to stream over the region from the northwest with the
best forcing occurring over the eastern half of the forecast area
where strong cold advection occurred overnight.

The jet stream is oriented north-northwest-south-southeast in western Colorado but
enhances to an impressively strong 140kts along the Utah-Colorado border
this afternoon. Surface winds will likely be spatially complicated
with low cloud ceilings inhibiting mixing at times but showers
transporting momentum to the surface at times too. Already this
early morning down trees and powerlines have been reported along
Highway 550 between Ouray and Red Mountain Pass. These winds will only
strengthen through the day. Gusts of 80 to 100 miles per hour are expected in
much of the western mountains this afternoon and evening. Therefore
have issued a Blizzard Warning...above 8000 feet to capture
Douglas Pass also. Further North Highway 191 through the eastern
uintas will likely see very difficult conditions into this evening
under the jet. The far eastern mountains closer to the Continental
Divide will also have wind gusts but more in the 40 to 60 miles per hour
range.

As for snow...the ongoing forecast looks generally on track. The
deepest accumulations continue to favor the eastern half of the
forecast area...east of a line from Vernal south-southeast to Durango. West
of that line will see only light accumulations. The gusty winds
will help to stir the lower levels and keep daytime temperatures
mild with a rain snow mix at times up to as high as 7000 feet. The
snow will wind down this evening as the trough continues to shift
east. Snow levels will drop into the valleys even as snow showers
shift east. One area of concern for heavy snow tonight into
Tuesday morning is the Uncompahgre Gorge that will be under due
North Mountain tops winds at 20kts with 700mb temperatures down to the
efficient -12c. Will let the day shift look at this in detail.

Long term...(tuesday night through sunday)
issued at 405 am MST Monday Dec 22 2014

Flat ridging builds in Tuesday night and shuffles east over the
forecast area on Wednesday as another system moves into the Great
Basin. This storm is expected to push across our forecast area on
Christmas day bringing another round of snow to the high country
and a chance of rain or snow to the valleys. Timing of the wave
would bring the best chance for precipitation during the late
morning and afternoon hours with activity lingering over the
mountains into Friday morning. Will continue to ramp probability of precipitation up but
will not be issuing any products for this potential Christmas day
event until we start wrapping up the current storm. Dry conditions
then expected Friday afternoon and Saturday...with another storm
dropping into the region Sunday...bringing more snow to the
northern and central mountains and high valleys. Temperatures will
run near normal through the period. Winter has definitely arrived
on the West Slope.

&&

Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 405 am MST Monday Dec 22 2014

The jet stream over the forecast area this morning strengthens to
over 140 kts by this afternoon. This produces strong wind shear
below mountain top level...even mixing down to the surface at times.
Wind gusts of 35-55kt are possible at all airports. If the wind
is not gusting...low level wind shear will likely occur within
020 feet above ground level.

Showers will continue over mountains impacting all airports east of a
line from kvel south-southeast to kdro. For khdn ksbs kege kase...snow and
blowing snow will produce ceilings at or below 010 and visibility at or below
1sm. Other airports will have ceilings at or below 030 with scattered -snra
through this evening. Mountain obscurations will continue in clouds and
blowing snow. Conditions are expected to improve from west to east
after 06z tonight.

&&

Gjt watches/warnings/advisories...
Colorado...Winter Storm Warning until 6 PM MST this evening for coz005-
007>009.

Winter Weather Advisory until 6 PM MST this evening for coz003-
017-019.

Blizzard Warning until midnight MST tonight for coz003-017>019.

Winter Storm Warning until midnight MST tonight for coz002-004-
010-012>014-018.

Wind Advisory until 8 PM MST this evening for coz021>023.

Utah...Winter Weather Advisory until 6 PM MST this evening for utz023.

Blizzard Warning until midnight MST tonight for utz023.

&&

$$

Short term...Joe
long term...jdc
aviation...jdc/Joe

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