Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus65 kgjt 240402 
afdgjt

Area forecast discussion
National Weather Service Grand Junction Colorado
902 PM MST Tue Jan 23 2018

Short term...(tonight through Wednesday night)
issued at 1224 PM MST Tue Jan 23 2018

The shortwave trough responsible for overnight cloud cover and
isolated snow showers in the north has departed to the east this
Tuesday afternoon. In the wake of this system, sunny skies have
moved in to much of the western slope. Short term forecast
soundings do still indicate some residual moisture in the lowest
5kft from Craig eastward, and some upslope cloud cover will
linger through the evening in the northern mountains. High
temperatures will struggle today with strong inversions in place
in snow-covered valleys. Overnight, ridging will move in and with
clear skies and light winds, another night with below average
temperatures is expected. Low temperatures have been lowered from
guidance blends across the board for tonight, and by several
degrees in some of the typically colder locations such as Craig
and Gunnison. On Wednesday, the ridge axis passes through eastern
Utah and western Colorado and a mostly sunny and dry day is
expected. One more night of below average lows is expected on
Wednesday night and guidance blends have again been adjusted
downward.

Long term...(thursday through tuesday)
issued at 1224 PM MST Tue Jan 23 2018

Winds will pick up on Thursday afternoon ahead of the next storm
system. A 110kt jet will translate eastward over the western
slope through the day. Warmer surface temperatures will result in
better mixing, which will help translate some of the stronger
winds to the surface especially in the later afternoon hours.
Temperatures will run around 10 degrees above average with high
clouds spreading eastward and thickening toward sunset. Some
timing differences remain between major global models with regard
to precipitation for the late-week storm system. The GFS appears
slightly quicker and drier compared to the ECMWF, which has been
noted over the past few model cycles. Except for the eastern
uintas, it does appear as though any precipitation will hold off
until after 6pm Thursday. Light snow can be expected throughout
all ranges of western Colorado from Thursday night through Friday
around noon. The moisture stream associated with this system is
hardly impressive...with precipitable water anomalies barely creeping above
climatological averages during this time. However, forecast
soundings do indicate several hours of saturation within the peak
dendritic growth zone from the Park Range southward through the
Elk Mountains and Crystal growth could be rather efficient in the
higher terrain. Our first shot at snow accumulations with this
event reveals a general 2-5 inch snowfall in the northern and
central mountains, with 1-3 inches possible in the San Juans
before the light snow ends on Friday afternoon.

Northwest flow will keep clouds in place in the northern
mountains on both Saturday and Sunday. Very low-chance snow
showers are hinted at by some forecast guidance this weekend in
the park and elkheads, however confidence is low in any additional
accumulations at this range. Guidance is in good agreement
showing ridging returning to The Four Corners region early next
week before another trough brings precipitation back to the
central rockies by Wednesday.

&&

Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 900 PM MST Tue Jan 23 2018

An upper level ridge of high pressure will pass over the area on
Wednesday. This will bring light winds and mainly clear skies to
through Wednesday evening. Expect VFR conditions to continue.

&&

Gjt watches/warnings/advisories...
Colorado...none.
Utah...none.
&&

National Weather Service Glossary of Abbreviations