Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 261937

Area Forecast Discussion
National Weather Service Grand Junction CO
137 PM MDT THU MAY 26 2016

Issued at 137 PM MDT Thu May 26 2016

Snow showers have begun over the higher elevations of the southern
and central mountains early this afternoon. The CDOT camera at
Monarch Pass shows that snow has begun accumulating in the grassy
areas along the roadway. Expect showers to increase northward
across the Elk range and Vail Pass area through the next couple of
hours. At times in heavier convective showers and thundersnow,
snow or slush may accumulate on the road surfaces into early this
evening. Then once temperatures cool later this evening, roadways
may become snowpacked and/or icy as snow continues. While the
snow level may drop below 10000 feet at times, accumulating snow
will mainly be above 10000 feet. Therefore have issued a Snow
Advisory for the central Colorado mountains above 10000 feet for
travel impacts. Mainly Vail, Monarch and Independence Passes will
be affected.


.SHORT TERM...(Today through Friday)
Issued at 313 AM MDT Thu May 26 2016

An area of low pressure, currently over central Arizona, will
continue moving eastward this morning. As this occurs, specific
humidities will also slowly start increasing indicating an
increase in available moisture. QG forcing will also be on the
uptick as both the NAM and GFS show plenty of omega, or vertical
motion, moving in to the forecast area by daybreak. This is to be
expected as the center of low pressure moves across eastern Utah
and western Colorado. This center of low pressure will also advect
cooler mid level temps increasing instability which is borne out
by fairly high lapse rates.  With all these ingredients in place,
we can expect an increase in showers and thunderstorms across the
region. Examination of cross sections and sounding data does
indicate a fairly dry boundary layer which will keep showers and
storms relatively high based. One minor concern is coverage as the
HRRR and RAP13, very short range models, are nowhere near as
aggressive as the NAM/GFS/EC. Will be something to keep an eye on
as the day progresses and convection begins. A few inches of snow
still remain possible but only at the highest elevations of the
San Juans this afternoon. No highlights necessary in that regard.

Convection should start an hour or two before noon and continue
as the day moves forward. The Continental Divide and San Juans
look favored though all higher terrain will likely see some
convective development. While H7 winds are light, a few cells will
drift into valleys.

Plenty of clouds and precip will keep temps below normal as has
been the case for many days this month.

By Friday morning, the low pressure center will have shifted to
eastern Colorado and even through a short wave ridge builds in,
plenty of moisture beneath said ridge and heating will destabilize
the atmosphere to fire off some showers and storms. Coverage is
expected to be less than that seen on Thursday.

.LONG TERM...(Friday Night through Wednesday)
Issued at 342 PM MDT Wed May 25 2016

Residual moisture will fuel scattered to numerous showers and
thunderstorms during the afternoon/evening through much of the
long term period. In fact, this trend plays out during the
weekend and into the first half of the coming week as mean
troughing persists over the western U.S. Temperatures will recover
to near normal Saturday and will remain at, or a little above,
normal through early next week.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1038 AM MDT Thu May 26 2016

A storm system will track east-northeastward across the Four
Corners region this afternoon fueling scattered to numerous
showers over the area. Much of this activity will be focused over
the mountains, with the southern and central ranges favored.
However, a number of storms will drift over the central valleys
this afternoon/evening. This activity will be capable of briefly
lower VSBY to MVFR levels while bringing CIGS to near or below ILS
breakpoints. In addition, strong outflow winds to 40 mph may
result in abrupt and unpredictable wind shifts. Showers and
thunderstorms diminish later tonight.


.GJT Watches/Warnings/Advisories...
CO...Winter Weather Advisory until 6 AM MDT Friday for COZ010-012
     above 10000 feet.



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