Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 230540

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1140 PM MDT Sun Oct 22 2017

.SHORT TERM...(Tonight through Monday night)
Issued at 152 PM MDT Sun Oct 22 2017

Cirrus entrained in northwest flow is expected to continue
sweeping southeastward across the forecast area tonight. A weak
shortwave trough and modest mid-level moisture is expected to
bring scattered snow showers to the Elkhead and Park Ranges late
tonight and Monday morning. Accumulations will be light with only
an inch or a little more expected above 10,000 feet and flurries
possible down to 8500 feet. Clouds combined with the passage of
the upper level disturbance will buoy overnight lows, especially
in the north.

A ridge builds over the western U.S. during the latter part of the
day Monday which will cause flow to weaken and shift to a more
northerly direction while clouds decrease. Little change in 7H
temperatures indicated in model data, so expect marginally warmer
afternoon temperatures, largely the result of increased solar
insolation. The continued influx of drier air from the north with
few clouds Monday night will cause lows Tuesday morning to dip
from 5 to 10 deg F across northwest Colorado. Elsewhere, overnight
lows will experience little change.

.LONG TERM...(Tuesday through Sunday)
Issued at 152 PM MDT Sun Oct 22 2017

The ridge over the West will hold Tuesday, then begins to
breakdown on Wednesday. In response, dry weather will continue
through midweek regionwide with temperatures running a few degrees
above normal for most locations.

Models continued to suggest changes in store Thursday, however
there still isn`t consensus. As has been the case over the past
several runs, the GFS and Canadian suggest a low amplitude
shortwave-trough will deal a glancing blow to the northern and
central Continental Divide Thursday into Thursday night. The GFS
indicated light accumulations of mountain snow while the Canadian-
NH doesn`t generate any precipitation. In contrast, the ECMWF
persisted with a more vigorous shortwave over the same period, its
impacts extending farther to the west. Snow in the northern and
central Colorado mountains with this solution have the potential
of yielding impactful snow across the higher elevations including
Rabbit Ears and Vail Passes. Given model disparities will hold the
line with a blended forecast which suggests modest precipitation
chances, mainly over the Elkhead, Park, Gore, Flat Tops and
portions of the Elk Mountains.

Despite model differences, by Friday afternoon, both models
indicated dry weather will return and will continue through the
weekend as high pressure becomes reestablished over the West.
However, an influx of colder air Thursday and Thursday night is
expected to drive temperatures below normal Friday into Saturday.
By Sunday, models suggest the airmass will modify to near normal


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1140 PM MDT Sun Oct 22 2017

Cloud cover will increase along and north of a line from KCAG to
KASE as weak upper level disturbance treks across the region
tonight and tomorrow. This may trigger a few light snow showers
over the northern mountains in western Colorado between 09Z and
21Z with brief periods of mountain obscuration. No impacts are
expected at terminal sites outside of an increase in mid level
cloud cover with CIGS remaining above ILS breakpoints.




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