Wasatc h
Cache National Forest
In partnership with: The Friends of the Utah Avalanche Forecast Center, Utah Department of
Public Safety Division of Comprehensive Emergency Management, Salt Lake County,
and Utah State Parks
: http://www.avalanche.org/~uac/
Avalanche
advisory
Saturday, NOVEMBER 14, 2003 7:30 am
Good morning, this is Bruce
Tremper with the
Current Conditions:
With just a trace of new snow
last night and yesterday, storm totals are around 15 inches in the past couple
days and around two feet in the past week.
Settled snow depths range are 2-4 feet and the coverage is getting
pretty good Yesterday’s freezing level was
around 6,000’ with damp snow below about 8,000’ and fairly light and fluffy
snow at upper elevations. With partly
cloudy skies overnight the temperature dropped to 18 degrees at 8,000’ and on
the ridge tops it’s blowing 5-15 mph from the
southwest and temperatures are around 20 degrees.
Avalanche Conditions:
Backcountry skiers triggered
9 different avalanches I know of yesterday in the backcountry, some intentional
and some unintentional. There were yet three
more in the East Bowl of Silver Fork, One on Rocky Point near Alta, one at
Alta, which is not yet open for the season and is not doing any avalanche
control and four in the McConkies Bowl in a closed
area of Park City, which the skiers had to ski out of the moving slides. I have more details on these slides on our
more detailed recorded information line at 364-1591 and I will also post a list
and photos on the web at www.avalanche.org,
click on Salt Lake and then on Advisories.
All these avalanches fractured on the weak layer of frost or “surface
hoar” that formed on the surface of the snow last weekend, then two storms with
wind this past week piled on a couple feet of new snow, which became the slab. Most of the slides are a couple feet deep and
50-100 feet wide. In Utah, because we
live in such a dry climate, we usually don’t get many avalanches on surface
hoar, which is lucky since it’s undoubtedly the trickiest weak layer on the
planet. It’s very thin and hard to see
in a snow pit wall and it’s very pockety, meaning that it might exist on one
slope, and not on the next. Also, it’s
very persistent, avalanches tend to occur in very
unusual places and even on slopes as gentle as 32 degrees. Most of the problem seems to be above about
9,000 feet on northerly through easterly facing slopes but we don’t have a very
good handle on the pattern distribution.
It seems to be a bit of a crap shoot.
Until this layer of surface hoar adjusts to its load, you will need to assume
each slope is guilty until proven innocent.
Play it conservative and stick to slopes under about 32 degrees. If you must push slope angles today, do lot’s
of digging in the snow and do stress tests to look for the characteristic
clean, spring-loaded shears on a thin layer of sparkly feather-like crystals.
Bottom Line (
The avalanche danger is CONSIDERABLE today on slopes facing the north through east
quadrants of the compass, above about 9,000’, and steeper than about 34
degrees. Considerable means that human
triggered avalanches are likely. There is a MODERATE danger on south facing slopes and all
slopes less than about 34 degrees.
Mountain Weather:
We have several storm pulses crossing our area in the near future with a
weak system this morning, then another one tonight and yet another one on
Sunday. These might add 3 inches today, 3-6
more inches tonight and few more inches on Sunday. Ridge top winds will blow today from the
southwest 10-15 mph and become stronger on Sunday and turn northwesterly. Ridge top temperatures will remain in the mid
20’s and down at 8,000’ the high today should be near 30 with the overnight low
in the mid 20’s. The extended forecast
calls for another storm on about Thursday and then becoming cold with another
storm by next weekend.
For specific digital forecasts for selected mountain areas from the
National Weather Service, click the links below or choose your own specific
location at the National
Weather Service Digital Forecast Page:
|
3-Day Table |
3-Day Graph |
7-Day Table |
General
Information:
Starting on Monday, Alta Ski Area will be closed to uphill traffic
because of avalanche control and slope preparation for their opening on
Thursday.
If
you are getting into the backcountry, please give us a call and let us know
what you’re seeing, especially if you trigger an avalanche. You can leave a message at 524-5304 or
1-800-662-4140. Or you can e-mail an
observation to uac@avalanche .org, or you can fax an
observation to 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.
Drew
Hardesty will update this advisory Sunday morning.
Thanks for calling
_____________________________________________________________________________
For more detailed weather
information go to our Mountain Weather Advisory
National
Weather Service - Salt Lake City - Snow.
For an explanation of
avalanche danger ratings:
http://www.avalanche.org/usdanger.htm