Wasatch-Cache National Forest: In partnership
with: Utah State Parks and
Recreation, Friends of the Utah Avalanche Center-Logan, and Utah State
University College of Natural Resources.
Logan area Avalanche Advisory
7:30, Saturday March 29, 2008
Hello
and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.
It’s Saturday March 29th, at 7:30
in the morning. Today’s advisory is
brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Import Auto.
Current Conditions:
After dropping only a couple inches on the Bear River Range, the snowfall focusing cold front is on
its way south to set up camp across the central part of the state. Expect snow showers and cloud cover to
gradually diminish today, while west winds will continue to rake high
ridge-lines. You’ll be able to find
fairly good spring powder conditions today, especially in sheltered terrain at mid
and upper elevations in the northern part of the forecast zone… The Tony Grove
Snotel reports around 3 inches of water equivalent gain at upper elevations in
the last 8 or 9 days, which means lots of new snow. It was windy again last night, with the CSI Logan
Peak wind sensor reporting hourly average wind speeds in the 30 mph range for
several hours overnight with gusts of around 50 mph from the southwest. Its 18 degrees at 9400’ and 34 in Smithfield….
Avalanche Conditions:
The productive westerly
flow in the past week has been very generous to the farthest north mountains
and the region near the Idaho State Line, while leaving points south fairly
dry. Accordingly, avalanche conditions
vary greatly across the region. Thursday’s
storm dumped around a foot of fresh snow at upper elevations in the Central Bear
River Range and
persistent west winds caused extensive drifting of the fresh snow in exposed
terrain. We noticed a number of natural
avalanches involving new snow and triggered a few small wind slabs with cornice
drops in the Steam Mill Canyon Area, (3-27 photos) and (new photos). Yesterday, settlement and water vapor sublimation
within the new snow caused the snow to be remarkably more stable, but we could
still trigger long running sluffs and cornices were still sensitive. As is typical in the springtime, wet avalanches may become possible on steep slopes as
warmth turns the fresh surface snow into slush. You might find even smallish wet avalanches
entraining lots of mass and traveling far.
Relatively cool temperatures and lingering
cloud cover should help to keep the snow dry, but this time of year any solar
warming can be very intense and when the fresh snow becomes saturated is prone
to avalanching.
With
strong southwest winds overnight and plenty of fresh driftable
snow about, freshly formed wind slab avalanches are my primary concern. Wind
slab avalanches are most likely on steep upper elevation slopes with
significant deposits of recently drifted snow, mainly in the Central Bear River Range. Fresh drifts
should be fairly obvious, and you should avoid them on steep slopes. Many avalanche slide paths in the area are
well filled-in and smooth, so even relatively small wind slab avalanches might
run far or fast. Isolated persistent slabs are also still
possible on very steep slopes above 8000’ in elevation and facing the northern
half of the compass, and smaller wind slab avalanches or cornice falls might
initiate step-downs into buried weak layers creating deeper and much more
dangerous avalanches. The huge cornices in the region now present
an obvious danger, especially when it’s windy or warm. Large cornices will be sensitive to your
weight today and may break further back than you expect.
Bottom Line:
Overall
there’s a MODERATE avalanche
danger in the backcountry, and you could trigger wind slab avalanches on some slopes
steeper than about 35 degrees. The
greatest danger is on steep drifted or corniced slopes in the Central Bear River Range in exposed terrain at upper elevations, and dangerous
triggered wind slab avalanches are possible. Wet avalanches may become possible on some
slopes in the midday heat if the fresh
surface snow is warmed and becomes saturated.
Mountain Weather: The cold front is on its way south to
set up shop over Provo and the Western Uinta Mountains. We’ll see lingering
snow showers this morning and diminishing cloud cover this afternoon, with
continued westerly winds likely. We
should see a few more inches of accumulation tomorrow, but most of the
storminess looks like it’ll stay to the south.
Another storm will affect the region mid-week.
General
Announcements:
Check
out the images page for photos of some of this season’s avalanches.
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.
