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 25, 2008 11:30 am
Good afternoon, this is
Special Announcement:
This will likely be
our last advisory of the season.
Current Conditions:
We had a pleasant
weather surprise yesterday. We were expecting
less than 6 inches of new snow but upper Big and Little Cottonwood Canyons
ended up with over a foot and as much as 16 inches in some places. By today, most of the new snow has settled
out to about 8 inches and about a foot at the highest elevations. The snow is slightly stiff, if you’re a snow
snob, because there was some graupel in the new snow, but otherwise quite
delightful, especially for the end of April.
Today’s sun put a thin sun crust on most slopes except for the upper
elevation north facing slopes, which should be the only ones with decent powder
for Saturday morning. Temperatures this
morning were around 10 degrees and it warmed up to the mid 30’s on the
ridgetops with a moderate wind from the northwest.
Snow and Avalanche Discussion:
Yesterday when the
snow rained down fast and furious during the snow squalls that moved through,
the snow was sensitive and several people were able to make the snow crack and
occasionally kick off some shallow, soft slab avalanches. Last night at 7:00 pm in the evening someone
was caught and carried in an avalanche they triggered in Little Cottonwood
Canyon on the south side of Little Superior.
They rode the avalanche 200 feet and got out before it ran 2/3 of the
way to the road below. The avalanche was
100 feet wide and 18-20 inches deep. Someone
also noticed a small natural slab, which probably released yesterday, in Ivory
Flakes in Cardiff Fork of Big Cottonwood Canyon.
The snow has settled out quite a bit by today and it was much less
sensitive. I suspect that since the old
snow surface was so warm and wet, combined with a little sun, it caused rapid
settlement and bonding in the new snow.
Even in this morning’s sun, there was surprising few wet sluffs on the
steep south facing slopes.
For those heading out on Saturday and through the weekend, the snow should be
fairly well behaved but you will need to watch for a couple of the usual
avalanche problems we have with spring storms:
First, watch for a few, lingering, sensitive
wind drifts especially along the upper elevation slopes from northwest winds. Be sure to practice slope cuts, jump on test
slopes and dig down with your hand to test the snow.
Second, as the strong spring sun warms up the snow you should watch for wet
sluffs on the steep, sun exposed slopes, especially in the heat of the
afternoon. The snow usually starts
producing rollerballs (pinwheels) before it starts producing larger sluffs.
Mountain Weather:
The weekend should be mostly
sunny with ridge top high temperatures near the mid 30’s and a 15-20 mph wind
from the northwest. On Sunday the high
should be near 44 and near 52 on Monday. Overnight lows should be in the mid 20’s,
rising to near freezing on Monday.
The extended forecast calls for continued nice weather with the chance of
another shot of snow about Thursday.
You can easily monitor the weather yourself by using the following links:
Alta
Forecast Graph from the National Weather Service (I love this product).
48-hour
weather charts of past temperature and wind (a product produced by our own
Cottonwood
Canyons Forecast from the National Weather Service.
Announcements:
If you see any avalanches or interesting snow conditions, please leave us
a message at (801)
524-5304 or 1-800-662-4140, or email us at [email protected]. (Fax 801-524-6301).
UDOT highway avalanche control work info can be found by
calling (801) 975-4838.
Watch video tututorials and fieldwork from UAC staff at our YouTube
channel.
The UAC depends
on contributions from users like you to support our work. To find out
more about how you can support our efforts to continue providing the avalanche
forecasting and education that you expect please visit our Friends page.
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 our last advisory of the season. I will put on an end-of-season message on
Monday.