Wasatch Cache National Forest
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 Salt Lake County.

keeping you on top


Wednesday, December 19, 2007  7:30 am
Good morning, this is Evelyn Lees with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  Today is Wednesday, December 19, 2007 and it’s about 7:30 am.


Current Conditions:

It’s the good four letter “s” word this morning – snow!  The first in a series of storms has laid down 6 to 12” of about 7% density snow, with the greatest accumulations in Big Cottonwood, the northern Park City ridge line and the Ogden area mountains.  Temperatures are fairly warm this morning, in the upper teens to low twenties.  The southwesterly winds were brisk last night, with the higher ridges averaging 20 to 30 mph, with gusts to 50.  This morning, winds have decreased, to less than 20 mph even across the highest peaks.  The welcome new snow is covering a wide variety of old snow surfaces – hard wind slabs, sun crusts, settled powder and old tracks, and will greatly improve riding, turning and snowshoeing conditions.


Avalanche Discussion:

No new avalanche activity was reported from the backcountry yesterday, though it was still possible to crack out some of the old hard wind slabs, especially where they are sitting on surface hoar or light density snow mixed with near surface facets.


The new snow is falling on a wide variety of old snow surfaces, which will be hidden beneath a coating of white today.  This will make backcountry travel tricky, as the bonding of new snow is dependent on the old snow surface that you can’t see and which varies over very short distances.  A small test slope in one location may not be representative of a larger, adjacent slope.  The steep, wind drifted slopes will be the most sensitive, and should be avoided.  Approach other steep slopes with caution.  The avalanche danger will peak this morning during the period of heaviest precipitation, or any time you’re in an area where the wind speeds increase and start to drift the snow. 


And then there is the continuing avalanche concern of the old October facets near the ground, which are refusing to gain strength in many locations.  This deep weak layer is found on northwest, north, and northeasterly facing slopes, above about 9,000’, and is most widespread in Salt Lake and Provo area mountains.  The southwesterly winds are loading extra snow onto this already weak structure, and these steep, upper elevation northerly facing slopes should be avoided because of the potential to break out dangerous slides 3 to 4’ deep and 100’ wide.


Bottom Line for the Ogden, Salt Lake, Park City and Provo area mountians:

The avalanche danger is CONSIDERABLE on any steep, wind drifted slope, where natural avalanches will be possible, and human triggered slides probable.  Particularly avoid the northwest, north and northeasterly facing slopes, above about 9,000’ where slides have a potential to break out on deeper weak layers.  The avalanche danger is MODERATE on steep slopes without wind drifting and without the layer of facets near the ground.  Slopes less steep than about 35 degrees have a generally LOW avalanche danger today, and will have very good turning and riding conditions.  There will be an increasing avalanche danger Thursday with additional snow and strong winds in the forecast.


Mountain Weather: 

A moist storm system moving across the area this morning will bring another few hours of light to moderate snow, before tapering off around noon.  An additional 3 to 6” of snow is possible.  The southwesterly winds may increase into the 10 to 20 mph range, with gusts to 30, with the highest ridges and peaks having hourly averages of up to 20 to 30 mph, with gusts in the 40’s.  Temperatures will be in the low 30’s at 8,000’ and in the upper teens at 10,000’.  After a short break this afternoon and evening, it will be “full conditions” tomorrow as a second, stronger storm arrives with more snow and powerful, southwesterly winds.



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

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.

Bruce Tremper
will update this advisory by 7:30 Thursday morning.