Thursday January 10, 2008
Hello and good morning, this is Toby Weed of the
Current Conditions:
The local
mountains picked up another healthy shot of snow, with the Tony Grove Snotel
reporting 1.7 inches of water equivelent gain since Tuesday afternoon and the
Ben Lomond Peak Snotel showing an increadible 3.7 inches in the same time
frame. There’s now 78 inches of total
snow on the ground at Tony Grove, with the top 3 feet or so consisting of soft
powder. A west wind kicked up in the
last couple hours at the Campbell Scientific weather station atop Logan Peak,
now averaging over 20 mph with gusts in the 30s. Its 5 degrees this morning at
9400’. The deep deep snow will probably
continue to keep most of us out of trouble.
You’ll find difficult trail breaking conditions, and expect to get your
sled stuck multiple times if you try to punch it up through untracked routes to
upper elevations.
Avalanche Conditions:
I noticed a couple wind slab
avalanches low in
The additional weight from
yesterday’s storm might be just enough to put some slopes over the edge. I’d not be surprised to see evidence of a few
full-depth natural avalanches on slopes cursed by faceted snow near the ground
and overloaded by all the new water weight.
The good news is that the Deep Slab instability caused by faceted or
sugary snow near the ground is now so deeply buried in many places that your
weight alone is probably not enough to activate it. The bad news is that you might not get any
tell-tail signs of danger until you actually trigger the slab from a shallow
spot. Potential large hard slab
avalanches could be several feet deep, very broad and deadly. Possible trigger
spots include rocky or generally shallow areas, like cliffy lower elevation areas
or upper elevation slopes scoured by previous winds. Possible triggers include overrunning smaller
wind slab avalanches, additional loading from heavy snow and wind drifting,
cornice falls, and unwary Humans.
Increasing winds and additional
snowfall today will cause a rising danger.
Watch for freshly formed or building wind slabs, and avoid them on steep
slopes at all elevations. Be wary of the
dangerous combination of faceted snow near the ground and recent drifting on
slopes with shallow overall snowcover at mid and lower elevations.
Bottom Line:
There’s a CONSIDERABLE danger and you
could trigger wind slab avalanches at any elevation on steep slopes exposed to
drifting in the backcountry. Deadly
triggered deep slab avalanches are also possible on slopes with existing weak
snow near the ground, mainly in exposed upper elevation terrain. Increasing winds and snowfall today could
cause the danger to become more widespread.
Today, avalanche training and experience are essential for safe
backcountry travel.
Mountain Weather:
Clouds thickened overnight as the next storm in this
year’s so-far very productive series is quickly moving into the area. The National Weather Service has issued a Snow
and Blowing Snow Advisory for the mountains around Logan from 11:00 this
morning through tomorrow afternoon. Today we’ll be in an often productive warm
air advection flow, with the cold front scheduled to arrive sometime tomorrow
morning. A bit more snowfall is expected
on Saturday afternoon, before a short-lived high pressure system builds into
the region, bringing hazy conditions to the valleys for Sunday and Monday. Models are still in disagreement about
potential storminess around Tuesday.
General Information:
I will give a free avalanche
awareness talk for snowmobilers at Renegade Sports tonight at
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.