Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 191015
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
415 AM MDT Fri May 19 2017

.SHORT TERM...(Today through Saturday)
Issued at 415 AM MDT Fri May 19 2017

The closed low pressure system responsible for the return to
winter-like conditions in the mountains and some of the high
valleys was centered over Paonia early this morning. The cold,
unstable, and moisture wrapped system continued to generate light
to moderate snowfall over portions of the central and northern
mountains and adjacent valleys overnight.

The low will shift slowly eastward during the day according to
models. Dynamic and orographic lift not all that impressive
beneath the low circulation. However, instability beneath the cold
core low combined with a shift in flow to the north as the high
pushes eastward is expected to bring an uptick in snowfall over
the mountains this afternoon. Additional accumulations aren`t
expected to be as impressive as during the early phases of this
storm, but still impactful. Isolated embedded thunderstorms may
bring locally higher amounts. Therefore, will continue Winter
Storm Warnings over the central and northern Colorado mountains
and the Winter Weather Advisory for the eastern Uinta Mountains.

Snow decreases tonight as the low center continues to shift over
the central High Plains. Prominent wrap-around moisture may keep a
few isolated showers continuing over the Continental Divide in the
north through sunrise Saturday. Meanwhile, lingering cold may
cause lows to reach freezing again for some of Colorado`s
southwestern valleys. Therefore, will hoist what should be the last
Freeze Watch for awhile for the latter part of the night through
early Saturday morning.

Instability, orographics and residual moisture combined with an
influx of moisture from the northwest will bring scattered showers
and a few thunderstorms to the northern and central mountains
Saturday afternoon. Warmer air begins filtering into the area
which will drive snow levels to near 10,000 feet and above. Though
temperatures will be milder, don`t expect highs to recover to
normal levels until the latter part of the weekend.

.LONG TERM...(Saturday night through Thursday)
Issued at 415 AM MDT Fri May 19 2017

The upper low will move into Ontario and the northern Great Lakes
by Sunday with a few shortwave disturbances rotating around the
periphery, clipping our northern mountains for a chance of some
convective showers developing each afternoon from Sunday through
Tuesday. The ridge of high pressure will build over the Pacific
Northwest by Tuesday night into Wednesday and slide over the CWA
through Thursday, leading to mostly drier conditions. Still kept
some isolated shower activity over the mountains due to
uncertainty in the models that far out in when it moves the
ridge overhead. Regardless, temperatures will rebound and warm
back up to normal levels by Sunday and continue towards above
normal by mid-week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1133 PM MDT Thu May 18 2017

Some low to mid level ceilings continue to persist across much of
the forecast area this evening as the area of low pressure
continues to move across western Colorado. A few snow and rain
showers will persist overnight though TAF sites will likely not
see any of this precipitation. The lower ceilings will likely
persist through tomorrow with gradual improvement after 18Z or so.
A few instability showers will pop again tomorrow afternoon, with
a thunderstorm or two also possible, but coverage should be less
than seen today.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Freeze Watch from late tonight through Saturday morning for
     COZ011-020-021.

     Freeze Warning until 10 AM MDT this morning for COZ011-020-021.

     Winter Storm Warning until 6 PM MDT this evening for COZ004-009-
     010-012-013.

UT...Winter Weather Advisory until 6 PM MDT this evening for UTZ023.

&&

$$

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



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