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Area forecast discussion 
National Weather Service Grand Junction Colorado
300 PM MST sun Nov 29 2015

Short term...(tonight through Monday night)
issued at 300 PM MST sun Nov 29 2015

The Thanksgiving week storm is almost over. The closed low which
has been spinning over the Great Basin is finally looking to make
its exit by tomorrow afternoon. Despite very low dbzs on the
radar...light snow continues to fall across areas of the Grand
Valley and San Juans. Cloud tops have been significantly
increasing throughout the day today across western Colorado along
an area of higher lapse rates and q vector convergence. Another
line of increased cloud tops has developed across eastern Utah as
well this afternoon...just ahead of the center of circulation.
This enhanced activity is moving rather quickly as the low
pressure system takes flight to the sub advisory
snow accumulations are expected.

The moisture availability is prognosticated to decrease around
midnight...which correlates well with the cold frontal passage
and wind shift to northwesterly winds overnight.

Monday...the southern portion of the tumbling low will move onto
the plains in the morning with the -32c cold core passing over the
park/Gore Range. The parent low over Wyoming also is pulled east
through the afternoon leaving sheared energy over the northern County Warning Area
Monday evening. The park/Gore/Flat Top ranges are primed for snow
production with the dendritic growth region at mountain top and near
saturation. Still model guidance produce relatively light quantitative precipitation forecast and
even at 25:1 ratios snow amounts top at around 6 inches. There
will be less snowfall or a break in snowfall Monday afternoon
under weak warm advection before light accumulations resume
Monday night. Valley fog is possible in most northern and central
valleys where there is snow on the ground.

Long term...(tuesday through sunday)
issued at 300 PM MST sun Nov 29 2015

A highly amplified slowly progressive flow dominates these
periods with the next Pacific low timed to impact the region next

Tuesday...the upper flow veers to north between the Great Lakes
low and Great Basin ridge. Strong valley inversions remain in
place under warm advection aloft. Morning fog is possible
Wednesday and Thursday across the northern and central valleys.

The ridge axis passes on Thursday as the next Pacific trough
works onshore. Increasing SW flow on Thursday brings a strong
warming trend to the high country and a chance to erode some of
the higher valley inversions too. The remainder of valley
inversions are expected to break on Friday as a cold front works
into Utah. This splitting trough is currently timed to move
through the region next Saturday with the favored ec forming a
closed low over the southern County Warning Area. If this timing is accurate then
snow showers could linger in the eastern mountains into Sunday.


Aviation...(for the 00z tafs through 00z Monday afternoon)
issued at 300 PM MST sun Nov 29 2015

The persistent closed low sweeps through the region over night.
Snow will become widespread over the central and southern
mountains overnight. All taf sites will likely see ceilings below 030
visibility blow 3 sm in -sn/snow through 12z. Exceptions to this are at
kvel kcny kdro where -sn will be more scattered in nature. Mountains will be
mostly obscured. Ceilings will diminish from west to east through the
morning. Valley fog could impact taf sites after 06z through 15z.


Gjt watches/warnings/advisories...


Short term...jam/Joe
long term...Joe

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