Area Forecast Discussion
Issued by NWS Grand Junction, CO

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839
FXUS65 KGJT 221731
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1131 AM MDT Tue Oct 22 2019

.SHORT TERM...(Today through Wednesday)
Issued at 213 AM MDT Tue Oct 22 2019

Mid-level clouds overspread much of northwest and central Colorado
early this morning in response to weak warm air advection working
on moisture entrained in northwest flow. Some light snow indicated
at observing sites east of the Continental Divide resulting from
orographic lift which can be assumed to be occurring over the
ridges comprising the Divide as well.

Models indicated light snow is likely to continue over the Elkhead
and Park Mountains throughout the day as moisture continues to
stream across those ranges. However, moisture depth not all that
impressive and as a result expect 1 to 3 inch accumulations,
mainly above 9000 feet. Little change in conditions are expected
tonight so additional snow is likely across the aforementioned
areas with another 1 to 3 inches in store.

After a brief downturn Wednesday morning, expect snow showers will
again pick up across the northern and central Colorado mountains,
and possibly the eastern Uintas as well, as a mid-level shortwave
trough and its surface cold front move over the northern half of
the forecast area during the afternoon. Despite dynamic forcing,
moisture levels remain modest and as a result, snowfall
accumulations are expected to remain light.

Snowfall accumulations aren`t likely to reach advisory criteria
over the next 36 hours, therefore will not be hoisting any
highlights with this package. Elsewhere across the region, partly
cloudy to mostly clear skies will prevail with continued dry
conditions. Temperatures are expected to moderate a bit today, but
will stay below seasonal norms. A bit milder tonight with similar
temperatures expected Wednesday afternoon for all but the
southern zones where continued warming will bring near normal
readings.

.LONG TERM...(Wednesday night through Monday)
Issued at 213 AM MDT Tue Oct 22 2019

Models carry the cold front mentioned in the short term discussion
across the southern half of the forecast area Wednesday night and
spread snow showers into the San Juan Mountains late in the night.
Showers exit the area by Thursday afternoon after which begins a
period of dry weather across the region which will persist through
late Saturday night.

Best chances for moisture arrive Sunday, though operational GFS,
ECMWF and Canadian all portrayed differences with respect to
timing and positioning of shower activity. Canadian and GFS were
most similar, both featuring a more progressive mid-level
shortwave trough pushing east of the Continental Divide by late
afternoon focusing shower activity over the northern and central
mountains. In contrast, the ECMWF was slower and deeper depicting
a positive tilt mid-level shortwave moving slowly southeastward
across the region from Sunday through Monday. This solution,
appeared colder and wetter than other solutions. The spread in
these solutions was apparent in the NBM solution which broadly
called for a chance of showers across the mountains with mainly
slight chances for the lower elevations.

Expect temperatures to rise to normal or above normal levels by
Saturday, however the arrival of the cold front from late Saturday
night through Sunday will cause readings to return to near normal
levels by early next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1125 AM MDT Tue Oct 22 2019

Low to mid level clouds will hang around northwest and central
Colorado through at least late afternoon, keeping CIGS below ILS
breakpoints at times across KHDN, KEGE, KRIL and KASE. Some
clearing will work in from the west, helping erode this cloud
layer by this evening. Otherwise, VFR conditions should prevail at
most sites with mainly light winds, although breezy conditions are
possible at times depending on amount of cloud cover.

&&

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

$$

SHORT TERM...NL
LONG TERM...NL
AVIATION...MDA



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