Hello, this is Toby Weed of the
Current Conditions:
A
powerful and slow moving spring storm is blasting the region with periods of
heavy snow and strong west winds as I write. The National Weather Service issued a Winter
Storm Warning for tonight through early Thursday morning, and favored upper
elevation areas could pick up a couple feet of snow in that time-frame. Several inches already accumulated this
evening, with around 4 inches recorded at the Tony Grove Snotel and 5 or 6 at
Avalanche
Conditions:
No
significant avalanches have been observed or reported in the region
recently.
Moderately
strong westerly winds accompanying periods of heavy snowfall will certainly be
strong enough to form significant drifts in lee slope starting zones and around
wind breaks and terrain features.
Fresh wind slab avalanches are possible on drifted slopes steeper than
about 35 degrees, and the danger of will rise, with human triggered avalanches
becoming probable on Wednesday with more accumulation and continued windiness.
Some natural wind slab avalanches
will also be possible at upper elevations if the storm continues as forecast.
Keep in mind that anytime heavy
snowfall is accompanied by strong winds, drifted snow can be deposited over wide
areas, and potential wind slab avalanches may not be limited to ridge tops and
normal wind breaks. As usual you
should avoid any fresh or building drifts on steep slopes.
With
significant accumulations, storm snow avalanches are possible on steep slopes in
more sheltered terrain. It will be
important to dig down and test the bond between the saturated old snow surface
and tonight’s new snow. Sometimes a
large temperature difference or other factors cause a poor bond resulting in an
increased danger of new snow avalanches. Also weak layers often develop within the
new snow while it’s piling up.
Not much of a problem with
less than a foot of new snow, but these issues could become real concerns with a
couple feet of accumulation as forecast.
As soon as the seasonally high angled sun comes out for any length of
time, (most likely on Thursday), the surface snow will quickly become saturated
and significant wet avalanches consisting of the new snow will be likely on
steep sunny slopes.
Bottom Line:
There’s a MODERATE danger in the backcountry, and human
triggered wind slab and storm snow avalanches are possible, especially on
drifted slopes steeper than about 35 degrees. The danger is likely to rise to
CONSIDERABLE during the day Wednesday on upper
elevation slopes with significant deposits of new or drifted snow. You’ll want to carefully assess snow
conditions and choose conservative routes while following safe backcountry
travel protocols to minimize the danger.
Mountain
Weather:
The slow
moving storm will bring continued heavy snowfall to the region through the day
on Wednesday. Snowfall is likely to
continue at upper elevations under a northwesterly flow until Thursday
morning. Expect clearing conditions
and gradually rising temperatures on Thursday, and a gradual warm-up as a high
pressure system rebuilds over the region for the weekend.
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 also recommend the recently-released Media Page, which
shows the forecast danger for our coverage areas across the state.
Please e-mail me at
[email protected] or leave me a message at 755-3638 if you see or trigger
avalanches in the backcountry. The information you provide may save
lives...
This advisory will expire on
Wednesday evening. I will update it again on Thursday night.
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.