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AVALANCHE ADVISORY
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Wednesday,
November 15, 2006 7:30 am
Good morning, this is Evelyn Lees with
the
Alta and Snowbird resorts will be closed to
uphill traffic today due to avalanche control work.
Current Conditions:
Under mostly clear
skies, temperatures have dropped into the teens this morning, with slightly
cooler air pooled in some valley bottoms.
The northwesterly winds have finally decreased, and are generally less
than 10 mph, with speeds in the low 20s across the highest peaks. When the snow finally tapered off yesterday
afternoon, the two day storm totals were fairly uniform throughout the range -
10 to 15 of dense, wind compacted snow.
Snowpack and Avalanche Conditions:
Yesterday, there were natural,
skier and explosive triggered avalanches throughout upper Big and Little
Cottonwood Canyons, all failing
on faceted snow near the ground. An
outstanding companion rescue effort saved the life of a skier in upper Silver
Fork yesterday. After skiing West Bowl,
the party was climbing back to the ridgeline on a more northerly facing slope,
when the slope fractured. One skier was
totally buried for about 10 minutes and unconscious when dug up, but his
condition rapidly improved. Brett
Kobernik has compiled a preliminary
accident report, which is posted on the web.
There were also three
large slides in Grizzly Gulch along the north facing Patsy Marley
ridgeline. At least one was triggered
remotely and was 1-2 deep and 400 wide.
Some slides were long running yesterday, a few initiated on lower angle
slopes, and many natural and explosive triggered slides were large, piling up 3
to 5 feet of debris. The activity was
most widespread at the higher elevations, above about 10,000. There were
reports of widespread cracking and collapsing.
There is a very
distinct pattern to these slides: they are all above about 9,200, on the shady
northwest through easterly facing slopes, and are failing on sugary, weak
facets at or near the ground. This nasty
weak layer formed on slopes where there was snow left from the early September
and October storms. Many slopes in the
backcountry did not slide naturally, and are just waiting for a trigger. While the snow may be a bit more stubborn
today, it will still be possible to trigger one of these large slides to the
ground. Stay off of and out from under
these shady, upper elevation slopes.
Bottom Line:
The avalanche danger
is CONSIDERABLE
on northwest through easterly facing slopes
above about 9,000, steeper than about 35 degrees. Large human triggered avalanches are
possible, and can be triggered on the slope or remotely from a distance, so
also avoid travel below steep slopes. At
mid and low elevations and the on sunny slopes that had no preexisting snow
prior to last weekends storm, the avalanche danger is LOW.
Mountain Weather:
An upper ridge will
bring warmer and drier weather today.
Highs will be near 40 at 8,000 and in the upper 20s at 10,000. Winds will be from the northwest, generally
in the 5 to 15 mph range, with averages 10 to 20 mph across the highest
terrain. Increasing clouds tonight, with
a weak cold front pushing into the area tomorrow, bringing a few inches of wet
snow. Light precipitation is also
possible on Friday and Saturday.
If there is anything
we should know about, continue to let us know by calling (801) 524-5304 or
1-800-662-4140, email [email protected]
or fax 801-524-6301
Finally, remember that
this avalanche bulletin describes general conditions and that local variations
always occur. Be sure to take a
reputable avalanche class and learn to judge local conditions as you travel.