Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 010935
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
335 AM MDT SAT OCT 1 2016

.SHORT TERM...(Today through Sunday)
Issued at 334 AM MDT Sat Oct 1 2016

Blocky pattern setting up with upper lows along the west coast and
across the eastern U.S. Building ridge in between with axis
setting up east of our forecast area. This brings southwesterly
flow back into the area with rather light wind fields today and
tonight. Still enough moisture lingering to kick off a few
showers and thunderstorms, with activity favoring the higher
elevations. With light steering winds, potential for valley
convection will be diminished as storms will likely dissipate as
they try to come off the higher terrain. Showers diminish this
evening with lack of significant forcing but will return on Sunday
as we start to see the first hint of our next weather change. This
will come in the form of increasing surface winds Sunday afternoon
as the western low digs into the Great Basin and tightens pressure
gradients. Temperatures will be running 3 to 6 degrees above
normal today, with another 2 to 4 degree bump up on Sunday as we
see the "warm before the storm" conditions come into play.

.LONG TERM...(Sunday night through Friday)
Issued at 334 AM MDT Sat Oct 1 2016

The upper low digs into the Great Basin Sunday night and Monday
then lifts into western Wyoming Monday evening. A strong vort lobe
whips through the bottom of the trough across NE Utah and NW
Colorado Monday afternoon-evening. The -21C cold core clips the
north overnight. Strong SW winds are expected ahead of the late-
day cold front. Moisture is limited with precipitable water values
around 0.6 inches across the north. This will limit rainfall but
may add outflow gusts to the already fast storm motion of 40-50
mph. Wind highlights may be needed, especially north. Temperatures
may be peaking early in the day, with values stabilizing and even
dropping by late afternoon as the cold front nudges into the
western zones.

Freezing temperatures are possible in many of our valleys Monday
night as the cold front drives through with moisture diminishing
from southwest to northeast. Should cloud cover depart early
enough, conditions will be prime for freezing temperatures across
most of our valleys, including the Grand Valley. Highlights will
most likely be needed, but still have a couple days and more model
runs to improve confidence and areal extent of the freezing
conditions.

Tuesday-Wednesday, cold advective NW flow will bring snow to the
north with snow levels lowering to around 6000ft overnight, then
rising to around 7500ft in the afternoon. This will likely give
Craig-Hayden-Steamboat some accumulating snow overnight that will
melt somewhat during the day. The GFS has a reinforcing shortwave
passing Tuesday night that brings another round of cold advection
and northern snow production. This may be overdone. Still early
season snow impacts are probable for the eastern Uintas and the
Park/Gore/Flattops as far south as Vail Pass.

Weak ridging builds in for Thursday and Friday for a drying and
warming trend but temperatures will stay below normal.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 334 AM MDT Sat Oct 1 2016

VFR conditions expected this morning with mid to high level
clouds moving overhead. Isolated to scattered storms are expected
after 20Z but will be limited to higher terrain. At this point, do
not expect any impacts at TAF sites but they will be monitored as
the day progresses.

&&

.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&

$$

SHORT TERM...JDC
LONG TERM...JOE/JDC
AVIATION...TGR/JDC



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