Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 010442

Area Forecast Discussion
National Weather Service Grand Junction CO
942 PM MST Wed Nov 30 2016

.SHORT TERM...(Tonight through Thursday night)
Issued at 315 PM MST Wed Nov 30 2016

Despite weak ridging aloft this Wednesday afternoon, a shallow,
saturated dendritic growth layer combined with light upslope flow
has kept some snow showers going in the northern mountains of
western Colorado. The 500mb ridge axis is currently progged to
cross the UT/CO border before midnight tonight. As it does,
additional moisture around 700mb will advect eastward into the
region with cloud cover increasing throughout eastern Utah and
western Colorado overnight. PoPs steadily increase north of I-70
through the morning hours on Thursday before peaking later in the
afternoon. 12z guidance is in good agreement portraying a
relatively meager snowfall event across the region in comparison
to the most recent systems. The most snowfall with the Thursday
event will fall over the eastern Uintas and Flat Tops...where 3 to
6 inches are likely through the evening. Lesser amounts, in the 1
to 3 inch range, are likely in the Book Cliffs and Grand Mesa area
before daybreak Friday.

.LONG TERM...(Friday through Wednesday)
Issued at 315 PM MST Wed Nov 30 2016

The shortwave trough responsible for light snow on Thursday will
dive south through Utah and close off south of the Four Corners
later on Friday afternoon. As it does, upper-level support for
light snow will diminish north of I-70 and precipitation will
taper off in all but the highest terrain after noon. Subtle
dynamic support for snowfall in the form of upper-level
divergence, as well as easterly flow below 700mb, will increase in
the southern Rockies on Friday afternoon. At the moment, guidance
is generally in agreement on a secondary maximum of light to
moderate snowfall developing over the central and southern
Colorado mountains including the Elk, Sawatch, and San Juan ranges
from noon Friday through early morning Saturday. A general 3 to 6
inch snowfall is likely across these regions by the time
precipitation ends by sunrise Saturday morning.

Dry northwest flow will return to the region on Saturday morning.
The break in the action will be short lived however, as low-level
moisture and upslope flow combine to return some light snow to the
northern Park range from Saturday afternoon through early Sunday
morning. At the moment, the NAM remains a bit of an outlier
showing enough moisture to produce some light snow in the north,
with the GFS and ECMWF depicting a drier solution for now.

After several weak systems late this week and weekend, a dramatic
change is in store for early next week as a more potent trough
dives through the Pacifc Northwest on Monday. Medium-range
guidance is in good agreement on the first piece of energy with
this system bringing precipitation to eastern Utah and western
Colorado beginning early Monday morning and lasting through
daybreak Tuesday. Thereafter, notable differences between
deterministic models emerge. The GFS develops an area of low
pressure over eastern Utah producing significant precipitation
over much of the central Rockies. The ECMWF develops this low
farther south, keeping the heaviest precipitation south of the
Interstate 70 corridor. Regardless of the outcome, cold air will
be plentiful from Tuesday onward with GEFS ensembles showing
500mb height anomalies 2 to 3 standard deviations below mean
values. Rocky Mountain snow lovers will certainly want to keep an
eye on the forecast over the next several days.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 931 PM MST Wed Nov 30 2016

VFR conditions will prevail across the area through about 12z,
then clouds will increase and lower across NE UT and NW CO with
snow showers increasing as well. The northern mountains will
become frequently obscured with MVFR cigs and vsbys developing at
KCAG, KHDN, AND KSBS. Cigs below ILS breakpoints will be possible
at KEGE and KASE after about 21z. MVFR and occasional IFR
conditions will be possible at KRIL, KEGE and KASE after 00z.




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