Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 302125
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
325 PM MDT FRI SEP 30 2016

.SHORT TERM...(Tonight through Saturday night)
Issued at 325 PM MDT Fri Sep 30 2016

The upper flow has veered to SW today introducing some mid-level
drying. Also less afternoon cloud cover has allowed for warmer
temperatures and differential heating. Both have added
instability. But we have lost upper level support so mainly
orographic storms will move to the east at 10 mph. Most storms
will end after sunset with a quiet night in store.

Saturday a trough deepens in the eastern Pacific pulling up a transient
ridge over Colorado. Moisture also diminishes a bit so afternoon storm
coverage will be less staying mainly over higher terrain. Daytime
and overnight temperatures will be a few degrees above normal.

.LONG TERM...(Sunday through Friday)
Issued at 325 PM MDT Fri Sep 30 2016

Sunday will be mild and marginally dry as a closed Pacific low
drops into northern California. Models have come into better
agreement with the track of the low with the less-impactful EC the
winner. The upper low digs into the Great Basin on 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.

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. Freezing
temperatures are possible in all but the lowest valleys Tuesday
night and Wednesday night.

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

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 325 PM MDT Fri Sep 30 2016

Scattered thunderstorms will persist over higher terrain until 03z
potentially bringing brief impacts favoring KTEX KASE KEGE. Only
isolated storms are expected 03z-06z. Otherwise VFR conditions
dominate, with isolated to scattered storms aft 20z Saturday
mainly limited to the higher terrain.

&&

$$

SHORT TERM...JOE+EH
LONG TERM...JOE+EH
AVIATION...JOE+EH



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