Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 210535

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1035 PM MST Mon Nov 20 2017

.SHORT TERM...(Tonight through Tuesday night)
Issued at 253 PM MST Mon Nov 20 2017

Fast moving Pacific wave will work across the northern and central
zones tonight as it slides down the front side of strengthening
Great Basin ridge. Moisture will slowly deepen across the northern
and central zones with more mid-level clouds showing up on
upstream observations. Light radar returns also picking up across
southeast Idaho and northwest Wyoming.

This activity will work southeast as leading edge of strong upper
level jet arrives drives over our northern zones this evening and
into the central mountains overnight. With improving jet
dynamics, moisture and favorable orographics, expect to see a
quick round of snow favoring the Park and Gore ranges between
midnight tonight and midday Tuesday. Amounts will be held in check
by the speed of this system and the fact our lower levels remain
quite dry. So top-down saturation will need to occur and model
soundings suggest this will somewhat slow. But it will happen and
we will see a quick 3 to 6 inches of new snow over our northern
mountains with lighter amounts trailing back over the Flat Tops
and into the Central Mountains from Vail to Aspen. Of course,
highest peaks may do a tad better, but overall this storm is
coming in under advisory criteria. Valleys locales from Craig
southeast toward Eagle and Avon should see a few light showers as
well, but no significant snowfall is anticipated in these areas.
The remainder of the forecast area will remain dry with moderated
overnight lows tonight thanks to the abundant mid and high clouds
moving through. This system exits the region Tuesday afternoon and
evening. Temps will remain at or slightly below seasonal normals
Tuesday with clouds helping to hold mins up again Tuesday night.

.LONG TERM...(Wednesday through Monday)
Issued at 253 PM MST Mon Nov 20 2017

Dry and mild conditions will be in place through much of the
Holiday weekend as a strong ridge of high pressure remains parked
across the western U.S. A few weak waves will top the ridge and
drive southeast across our northern mountains, dragging an
increase in cloud cover and possibly a few light showers Wednesday
afternoon and again Friday afternoon. Otherwise, we are looking at
several more days of dry with temperatures running a solid 5 to 10
degrees above normal. Beyond this time period, models still
hinting at a system coming through the region next Tuesday.
However, there remains large spreads between the EC and GFS with
the strength and placement of this system. Longer range outlooks,
into week two, still leaning toward a wetter pattern with
temperatures backing off a bit, but still favoring a warmer


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1024 PM MST Mon Nov 20 2017

Mid to high level clouds will continue through the overnight and
into tomorrow thanks to a passing wave that will bring some snow
to the northern mountains. A few showers are possible near EGE and
ASE but not expect any impacts at airports. Ceilings will remain
near 10K feet though areas up north may see lower ceilings from
time to time. VFR conditions will be the rule. Clouds will start
scattering out after 18Z.




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