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/
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Avalanche
advisory
Thursday, NOVEMBER
27, 2003 7:30 am
Happy Thanksgiving! This is Evelyn Lees with the
Current Conditions:
What a wonderful storm to
start the Thanksgiving weekend with. Storm
totals are about 8 - 10” in the Ogden, Provo and Uinta mountains, one to one and
½ feet on the Park City side, and 2 feet at the higher elevations in the
Cottonwoods, with densities of about 5%. A last few snow showers are being reported
early this morning from the upper Cottonwoods, but these should end shortly. Yesterday afternoon, the northwesterly winds
picked up into the 20 to 25 mph range across the higher ridges and continued to
blow through about midnight. Since then,
wind speeds have dropped to less than 10 mph.
Temperatures are once again in the single digits at 10,000’ and the
upper teens at 8,000’.
Today could be another “best
day of the year”, with deep light powder on all aspects. Expect some soft wind drifts in the open, upper
elevation terrain, and this afternoon’s sun could dampen the surface snow on
steep south and westerly facing slopes.
Avalanche Conditions:
Yesterday’s avalanche
activity was confined to the new snow only, with wind the key factor to the avalanche
pattern. In parts of the upper
Cottonwoods, where the snow piled up fast and furiously with a bit of wind, there
was a small natural avalanche cycle. These
were shallow, new snow soft slabs on steep, easterly facing slopes. Ski cutting by both backcountry travelers and
within the resorts produced very sensitive soft slabs in wind affect terrain with
some being triggered from a distance. These
avalanches averaged 1 to 2” deep, and 50 to 100’ wide, with a few in the
windiest locations up to 3’ deep or 300’ wide.
On steep slopes many of the slides were running further and faster than
expected. Outside of the wind affected
terrain, only sluffing occurred on the steeper slopes.
Today
should hold no surprises – approach steep slopes from the top,
and careful ski cutting and cornice drops should continue to be effective stability
tests. The winds drifts will be most
widespread on northeast, east and southeasterly facing slopes, but watch for cross
loading of wind drifts around other terrain features. The last few inches of snow may have hidden
many of these wind pillows, making them harder to detect.
If
skies clear later today as expected, the direct sun could trigger damp sluffs on
steep sunny slopes.
Bottom Line (
The avalanche danger is MODERATE on slopes steeper than 35 degrees with recent
deposits of wind drifted snow. These
wind drifts will be mostly confined to upper elevation ridgelines. Moderate means human triggered avalanches are
possible, while naturals are unlikely. Wind
sheltered terrain has a LOW avalanche danger today;
though expect loose snow sluffs on slopes approaching 40 degrees or steeper.
Mountain Weather:
Today will be delightful, with clearing skies, light winds, and warming
temperatures. Temperatures will warm
into the upper teens at 10,000’ and the mid 20’s at 8,000’. The northwesterly winds should remain light,
in the 10 to 15 mph range. Tonight, temperatures
will continue to warm as the winds shift to the southwest and increase into the
20 mph range. Friday will be mostly
cloudy and much warmer, with highs in the low to mid 30’s. This warmer and unsettled weather will
continue through the weekend.
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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:
General
Information:
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.
Andrew
McLean will update this advisory on Friday 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