Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Junction Colorado
1156 PM MST Friday Dec 26 2014

issued at 1153 PM MST Friday Dec 26 2014

Will allow the remaining winter highlights to expire at midnight.
Latest rap and arw models show light snow continuing to decrease in
areal coverage overnight. Kjgx radar returns were also shrinking.
Expect any additional snow accumulations to be generally less
than an inch.

The next storm expected to affect our area in the Sunday and Monday
was currently moving down the alaskan Panhandle per satellite

Update issued at 937 PM MST Friday Dec 26 2014

This latest storm continues to wind down this evening with the
upper trough axis from Arizona across Colorado to the northern plains.
Satellite water vapor images indicated a small jet maximum near the
Idaho/NV/UT triple point...which may keep the base of the trough
hanging back over the Desert Southwest until morning. Light snow was
still observed at many western Colorado sites...but gjx radar echoes were
slowing shrinking. If this trend continues will probably let the
remaining winter highlights expire at midnight though it is likely
that areas of light snow will persist through the night in the
cold northwest flow. Cold temperatures in store tonight.


Short term...(this evening through Saturday night)
issued at 318 PM MST Friday Dec 26 2014

Upper level low continues to move east across the forecast area
this afternoon. Light snow will continue to fall in many locations
before diminishing this evening. Have allow current highlights for
lower valleys to expire at 3pm and have cancelled highlights for
all of Utah and lower elevations of Colorado with the exception of
southwest Colorado 22/23 where highlights will continue. Have
also allowed highlights to continue for the mountains of western

As the upper low moves east overnight...expect precipitation to
diminish from west to east this evening. The best accumulation will
be over Colorado Mountain locations where a few inches of
additional accumulation is possible. Expect very cold temperatures
by Saturday morning with 700 mb temperatures around -16c.
Northerly dry flow will dominate the weather pattern Saturday with
cold temperatures and partly cloudy skies expected. The next
system will drop south into the northern Great Basin by Saturday
night and bring increasing clouds from the north with a slight
chance of snow over northern sections by early Sunday morning.

Long term...(sunday through friday)
issued at 318 PM MST Friday Dec 26 2014

A complicated storm system will dominate the weather pattern for
Sunday into the workweek. A low pressure system will drop south
into the Great Basin region on Sunday and Monday before closing
off over Nevada by Tuesday. The resultant deformation zone will
spread periods of light to moderate snow over the northern
sections of Colorado on Sunday morning and spread across the
central and southern mountains later Sunday and continue into
Tuesday. Models are still showing some inconsistencies regarding
timing and location of the track of this system. However...based
on current guidance expect a period of unsettled weather through
Tuesday with the potential for moderate accumulations especially
over mountain locations which may require winter weather
highlights. By midweek the closed low is forecasted to eject
slowly east...south of our forecast area with some potential
impact for southern sections of the forecast area but forecast
confidence is low on this model solution at this time.
Temperatures are expected to remain below normal through the


Aviation...(for the 06z tafs through 06z Saturday night)
issued at 937 PM MST Friday Dec 26 2014

The upper level trough will slowly slip eastward tonight with
flow aloft becoming northwest. MVFR ceilings/visibility with areas of light
snow will persist over northwest Colorado and all Colorado mountains overnight with mountain
tops obscured. Local IFR ceilings. Conditions improve over eastern Utah and
The Four Corners overnight and after 12z-15z across western Colorado as high
pressure temporarily builds in. High clouds spread across northestern Utah
and northwestern Colorado Saturday afternoon as a precursor to the next potential
storm Sunday-Monday.


Gjt watches/warnings/advisories...
Colorado...Winter Weather Advisory until midnight MST tonight for coz003-

Winter Storm Warning until midnight MST tonight for coz004-009-



short term...mpm
long term...mpm

National Weather Service Glossary of Abbreviations