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
Tuesday,
December 18, 2007 7:30 am
Good morning, this is Brett Kobernik with
the
Current Conditions:
Skies are
mostly clear this morning with temperatures again in the low twenties and high
teens. Southwesterly winds picked up
somewhat since yesterday afternoon gusting into the 30s and 40s along the
higher ridges but speeds are slower at the lower elevations compared to 24
hours ago.
Avalanche Discussion:
Winds from Sunday
night did a number to the snow surface at most elevations forming crusts and
some fresh drifts. There were a few
reports of some natural avalanche activity from the wind along with a few large
cornices releasing naturally in the
Fresh wind crusts and
drifts sit on top of lighter density snow that has faceted a bit or become weak
in many places. Aside from needing to
pay attention to these drifts today we will want to also consider how they will
act with the expected new snow added on top of them. This could be a bit tricky with the
inherently variable nature of wind drifted snow and how it’s changed the snow
surface dramatically from place to place.
The snow under these crusts isn’t exceptionally weak but weak enough to
demand some attention over the next few days.
We can’t forget about
our persistent weakness deeper in the snowpack either. This is going to get trickier as well as we
add more snow to it. Many northerly
facing slopes hold weaker snow near the ground.
This weakness varies greatly from place to place but is most pronounced
in the Cottonwoods. However, the mid
portion of the snowpack has gained tremendous strength in many areas over the
last week. This has “bridged” over the
weakness making it harder to collapse.
In simple terms, I don’t think this problem is going to be as “in your
face” as it has been over the last few weeks.
This is tricky as not every north facing slope is going to collapse or
avalanche. These are conditions that
tend to catch experienced people. I don’t
think we’ve seen the last of this buried weakness and would expect some
avalanching down to this layer with another significant load. The sure way to avoid it is to leave the
northerly facing slopes alone through this next series of storms and reassess the
snowpack afterward.
Bottom Line:
There is a
MODERATE avalanche danger in the
Mountain Weather:
We have two systems
that will produce snow through Friday. Today
we’ll see increasing clouds with temperatures in the upper 20s at the lower
elevations and low 20s along the ridgetops.
Southwesterly winds will continue in the 10 to 20 mph range gusting into
the 30s and 40s at the higher elevations.
Snowfall from this first weaker system will mainly be overnight tonight
with 4 to 6 inches expected and a bit more possible in the Cottonwoods. There will be a slight break on Wednesday
before a colder and better defined system moves in for Thursday into Friday
which should produce another good shot of snow.
Announcements:
The Wasatch Powderbird Guides will be not be flying today.
For an avalanche education class list, click HERE.
If you want to get this avalanche advisory e-mailed to you daily click HERE.
The UAC has temporary job openings for doing avalanche outreach in more rural
areas. Click HERE for info.
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.
If you’re getting out and see anything we should know about please let us
know. You can leave a message 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.