In partnership with: Utah Division of State
Parks and Recreation, The Friends of the Utah Avalanche Center, Utah Department
of Emergency Services and Homeland Security and
“keeping
you on top”
AVALANCHE ADVISORY
Friday,
April 27, 2007 2:00 pm
Good afternoon, this is
This will likely be the last avalanche advisory for
the season.
Current Conditions:
It’s been
great lately if you like corn snow. We
had a good refreeze last night with temperatures just under freezing and the
clear skies allow the heat of the snow surface to radiate out into space,
making the snow surface colder than the air temperature. But it’s all history now because we are having
a strong warming for the weekend.
Avalanche Discussion:
The warmer temperatures have already started some localized wet sluffs on the
high elevation north facing slopes. Wet
sluffs were noticed yesterday in upper Little Cottonwood Canyon and I’m
expecting much more of them this weekend.
First, I should talk a little about how wet avalanches work. As I’m always saying, snow is just like
people, it doesn’t like rapid changes. Wet
slabs tend to occur the first time that water percolates through a cold, dry
snowpack, which is the snowpack equivalent of a person taking a cold,
shower. It’s quite a shock at first but after
awhile you get used to it. In mid March,
we went through a big wet slab avalanche cycle when the cold, dry snowpack
warmed up for the first time. But the
temperatures were not warm enough to make the upper elevation north facing
slopes get soggy. When Craig Gordon and
I checked the snowpack this morning, we found lots of cold, dry snow above
9,500’ on northwest through northeast facing slopes. In fact, we also found some of our old enemy,
the cold, dry, faceted snow on slopes where the snowpack is less than two feet
deep. In other words, most other slopes
have already gone through their wet avalanche cycle, but the last to go are
always the upper elevation north facing slopes, and it looks like it will get
warm enough this weekend to make them active.
We’re expecting temperatures in the mid 80’s in
The bottom line is that you should watch out for northwest through northeast
facing slopes above 9,500’ for the next several days. If you must go onto them, do it in the
morning before they get wet and definitely get off of them after noon. It’s counterintuitive, but the south facing
slopes (which face directly into the sun) may actually be safer because they
have already gone through their wet avalanche cycle and they have well
established drainage systems, similar to a summertime snowpack. Remember that most of the ski areas are
closed for the season and no one is doing any avalanche control or rescue.
Mountain Weather:
It’s going to be a
real cooker for the next several days with sunny skies, light winds and 8,000’
temperatures in the mid 60’s. Ridge top
temperatures will be around 50 degrees and it will be 40-45 degrees on the
highest peaks. The peak of the warming
should be Saturday and Sunday and it will cool down slightly for a couple more
days with a strong cooling on Thursday.
Announcements:
UDOT highway avalanche
control work info can be found HERE
or by calling (801)
975-4838.
Our statewide
tollfree line is 1-888-999-4019 (early morning, option 8).
For our classic text
advisory click HERE.
We appreciate all the great
snowpack and avalanche observations we’ve been getting, so keep leaving us
messages at (801) 524-5304 or 1-800-662-4140, or email us at [email protected]. (Fax 801-524-6301)
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.
This will likely be the last avalanche advisory for the season and we will
issue an end-of-season message on Monday.