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Logan
Hello and good morning, this is Toby Weed of the
Current Conditions:
The cold is keeping the snow nice
on most slopes, and you’ll find good riding and turning conditions in the
backcountry across the region. It’s
currently -3 degrees at the Campbell Scientific weather station at 9400’ on
Avalanche
Conditions:
Large snowmobile triggered
avalanches continue to afflict the Western Uinta Range, and explosive control
work at ski areas in the Central Wasatch Range continues to produce large
avalanches running on weak faceted snow near the ground. Although we’ve had two
nice widespread natural cycles in the last week, (viewed on the 21st
and 25th), no more recent avalanches were observed or reported in
the Logan Area backcountry. We’ve noted lots
of settlement in the new snow since the productive Christmas Eve storm. And, water
vapor sublimation is creating small sugary grains in the new snow called near
surface facets. Both processes are
helping to increase snow stability by increasing the bond strength between slab
and underlying weak layers and taking tension out of the most recently
deposited slab.
I’m still concerned by the
possibility of triggered persistent slab avalanches in some areas, which will
be destructive and potentially deadly.
Suspect weak layers are made up of snow that was on or below the snow
surface in early December. The old
underlying snow is faceted or sugary and weak, and instabilities caused by
overloading slab layers are notoriously slow to heal. In most cases your weight probably won’t be
enough to trigger one of these monsters, but you might be able to trigger one from
a thin spot on the slab. The weight of a few snowmobiles at one time on a slope
or an overrunning smaller avalanche might also do the trick. Watch out for
steep rocky areas and slopes with shallow snowcover. Pay attention to obvious signs of instability
like recent avalanches on similar slopes, collapsing or woomphing
noises, cracking, or hollow sounding snow, and be willing to reassess your
route.
There are a few soft and stiffer wind
drifts that may still be sensitive, and increasing southwest winds today may
build a few more. These should be fairly
obvious and should be avoided on steep slopes.
Bottom Line:
Today there’s a MODERATE avalanche danger, and you
could trigger dangerous avalanches on some steep slopes in the backcountry. Triggered avalanches are most possible on upper
elevation wind drifted slopes with preexisting snow and steeper than about 37
degrees.
Mountain Weather:
A strong and somewhat moist
southwesterly flow will control the weather pattern through the weekend, and a
high pressure system will build early next week. Southwest winds picked up overnight and it’s
already snowing this morning in the
General Information:
Check out photos of avalanches in
the Logan Area on our images page.
Go to the Avalanche Encyclopedia if
you have any questions about terms I use in the advisory
I'm very interested to know what you're
seeing out there. Please e-mail observations to me at [email protected] or leave me a message at 755-3638,
especially if you see or trigger an avalanche in the backcountry. We keep all
observations confidential.
This advisory will expire in 24
hours from the posting time.
The information in this advisory is from the U.S. Forest
Service, which is solely responsible for its content. This advisory
describes general avalanche conditions and local variations always occur.
