Hello and good morning, this is Toby Weed of the
Current Conditions:
The
Avalanche
Conditions:
We’re getting reports of
significant natural and triggered wind slab avalanches in the
With all this nice light snow, we
experienced lots of wind drifting yesterday at upper elevations. Cornices
hanging over north and northeast facing slopes grew significantly during the
day as winds deposited loads stiffened snow on the slopes below. Shifting and strengthening winds and
continuing heavy snowfall will further build up cornices while forming drifts
and wind slabs in lee slope avalanche starting zones today. In some areas wind slabs likely formed on weak
sugary surface snow called near surface facets, and these are likely to be
sensitive to your weight today. Watch for vertical cross loading around terrain
features like sub-ridges, rock outcroppings, and gullies. Fresh powder may obscure
recent drifts or slabs, so don’t only trust your eyes. . 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.
I’m still concerned by the
possibility of deeper 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 deep
dwelling monsters, but you might awaken one from a thin spot on the slab. Watch
out for steep rocky areas and slopes with generally shallow snowcover. The
weight of a few snowmobiles at one time on a slope or an overrunning smaller
wind slab avalanche might also do the trick.
Bottom Line:
With heavy snowfall and intensifying winds in
the forecast, the avalanche danger will continue to increase today. This morning there’s already a CONSIDERABLE
avalanche danger in the backcountry.
Natural avalanches are possible and dangerous human triggered avalanches
are probable on upper elevation wind drifted slopes steeper than about 35
degrees. With additional significant snowfall and intensifying westerly winds,
the danger is likely to rise to HIGH on steep wind drifted slopes during the day. Both natural and human triggered avalanches
will be likely, and travel in avalanche terrain is not recommended.
Mountain Weather:
A cold front, packing strong WNW
winds and more significant snowfall will move southward across the region
today, and a high pressure system will build into the region for early part of next
week. West northwest winds and snowfall are
expected to increase throughout the morning and it’ll be downright stormy in
the mountains today. Expect up to 10
more inches of accumulation through tonight at upper elevations 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.