Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 100527
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1027 PM MST Sat Dec 9 2017

.SHORT TERM...(Tonight through Sunday night)
Issued at 240 PM MST Sat Dec 9 2017

As of 21z, a 584dm h5 ridge was centered over the western Great
Basin this Saturday afternoon. This ridge is providing the western
CONUS with dry and generally cloud-free weather which will remain
the case over the next several days. As mentioned in previous
discussions, the only notable challenge in the forecast is
overnight temperatures. Higher-altitude valley low temperatures
are notoriously difficult to forecast this time of year, and
guidance has been all over the place in terms of verification. In
general, drying near the surface will allow for overnight lows to
run at least as cold as last night and in some cases, colder.
Despite the general lack of snow cover, have dropped low
temperatures from lower guidance consensus in the valleys each of
the next three nights. Strong inversions underneath warming
temperatures aloft will result in poor conditions for anyone
wishing to engage in prescribed burning over the western slope
over the next few days.

.LONG TERM...(Monday through Saturday)
Issued at 240 PM MST Sat Dec 9 2017

The long term forecast will be dominated by the western ridge of
high pressure. Dry weather and light northwest flow is expected
each day through Friday afternoon over eastern Utah and western
Colorado with temperatures generally running 5 to 10 degrees
above average through the period. Of note for stargazers this week
is the Geminid meteor shower, one of the most prolific meteor
showers of the year, which peaks on the 13th and 14th. Popular
dark sky locations in southeast Utah and southwest Colorado should
see near-perfect conditions for the event. A few high clouds may
drop into northern Utah and northern Colorado by midnight on
Friday.

By the very end of the forecast period on Saturday, GEFS and EPS
ensemble guidance finally begin to hint at a breakdown in the
sprawling west-coast ridge. An analysis of ensemble h5 height
anomalies reveals a gradual trend to near-normal or even slightly
below normal heights by the middle of next weekend. Various
iterations of a storm system bringing some moisture to the central
and northern mountains have occasionally appeared on the past few
deterministic runs, but any skill or confidence in forecasting
accumulating snow remains very low at this time. "Patience" will
remain the suggested advice for powder-hungry recreationalists at
this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1027 PM MST Sat Dec 9 2017

VFR and light, typical diurnal wind conditions will continue for
the TAF period. The exception being at KEGE where have gone with
persistance forecast for development of low stratus late tonight
and continuing through mid morning Sunday. These conditions
spawned by particulates released by nearby industrial plant could
be highly variable, but TEMPO for conditions below ILS and IFR will
have to suffice for now.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...MAC
LONG TERM...MAC
AVIATION...BM


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