Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 292148
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
348 PM MDT Sat Apr 29 2017

.SHORT TERM...(Tonight through Sunday night)
Issued at 231 PM MDT Sat Apr 29 2017

An upper-level low pressure system continues to drift slowly south
and east through the southern Rockies this Saturday afternoon.
While much of the precipitation associated with this system has
remained east of the Continental Divide, some mid-level moisture
has managed to drain west of the Front Range. Light stratiform
snowfall continues over the Gore, Sawatch, and Elk Ranges, with a
more showery convective snowfall occasionally falling across
higher elevations on the Grand Mesa, Uncompahgre, and San Juans.
Occasional breaks in cloud cover will continue to fuel these light
snow showers through the afternoon and evening before surface
heating and resultant shallow instability rapidly diminishes after
sunset. Combined with a continued southward drift of the overall
storm system, cloud cover is expected to decrease from west to
east overnight. Freeze warning has been issued for the Delta-
Montrose corridor where confidence is high in sub-freezing
temperatures for several hours overnight. Farther north in the
Grand Valley, early evening cloud cover may hold temperatures high
enough to avoid a hard freeze. Will monitor cloud cover and
temperature trends for a possible Freeze Warning in this zone as
well.

Sunday will feature rising heights with light northerly flow
across eastern Utah and western Colorado. Guidance dries out the
mountains pretty well - however can not entirely rule out a stray
snow shower especially in central Colorado ranges. Afternoon high
temperatures will run 5 to 10 degrees below normal across the
western slope.

By Sunday night, a weak disturbance will round the eastern side of
a ridge of high pressure centered over the west coast. The main
impact for our region will be an uptick in cloud cover on Sunday
night into Monday morning. While lower levels will remain dry, an
increase in mid and upper-level moisture will result in some light
snow for the northern mountains starting before midnight Monday.

.LONG TERM...(Monday through Saturday)
Issued at 231 PM MDT Sat Apr 29 2017

Light snow will linger through the day on Monday in the mountains
along and north of I-70 as a subtle trough dives southward through
the Rockies. Once again, precipitation will fall only in the
higher elevations with a partly cloudy day expected elsewhere.
Another shortwave will pass late on Tuesday into Wednesday.
Forecast guidance has trended a bit stronger with this system in
today`s 12z runs, and some higher PoPs have been added to much of
central and northern Colorado and eastern Utah. Exact QPF totals
still vary greatly, but a mean of available guidance suggests
possible advisory-level snows at least for the Flat Tops and Park
Range by Wednesday morning.

This storm system exits the region quickly Wednesday afternoon and
evening with high pressure building in from the west. The second
half of the week will feature a return of springtime warmth as a
large upper-level ridge builds in from the west. Ensemble guidance
has been in good agreement over the past few days showing this
ridge moving in, and today`s GEFS and EPS solutions are no
expection showing +1 to +2 sigma h5 heights by Friday morning.
Valley temperatures in eastern Utah and western Colorado will
return to near the 80 degree mark by Thursday and Friday. Dry
weather is expected from Wednesday night through the first half of
next weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1105 AM MDT Sat Apr 29 2017

A storm moving through northern New Mexico will continue to pour
moisture into eastern CO, with some of it rotating over the CO
mountains. Most CO mountains and high passes will remain obscured
through 06z this evening, with improvement thereafter. Cigs
reaching ILS breakpoints will be frequent until about 00z this
afternoon at KASE, KEGE and KTEX.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Freeze Watch from 9 PM MDT this evening through Sunday morning
     for COZ006.

     Freeze Warning from 9 PM this evening to 9 AM MDT Sunday for
     COZ011.

UT...None.
&&

$$

SHORT TERM...MAC
LONG TERM...MAC
AVIATION...CC



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