Wasatch 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

The Utah Avalanche Center Home page is: http://www.avalanche.org/~uac/

Avalanche advisory

Thursday, February 27, 2003

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Good Morning. This is Evelyn Lees with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Thursday, February 27, 2003, and it’s 7:30 in the morning. We would like to acknowledge one of our partners, the Friends of the Utah Avalanche Center, generously supported by Alta Ski Lifts.

Current Conditions:

A moist, unsettled weather pattern continues over northern Utah. Skies are partly cloudy this morning, and winds very light - less than 10 mph, even across the highest ridges. Temperatures are frosty, and have dipped into the single digits at most locations. Most slopes have high-quality settled powder, with zipper crusts on a few of the sunny slopes.

Avalanche Conditions:

No new avalanche activity was reported from the backcountry yesterday, though several parties reported collapsing on southerly facing slopes. With time, the snowpack is adjusting to the load added since Saturday, and the chances of triggering a slide decrease a bit each day. However, the consequences if you get caught in a slide have not diminished.

Recent slides have involved a variety of weak layers and have occurred on almost all aspects of the compass, with northeast, east and southeast facing slopes the most active. Within the new snow, you can still expect sluffing on steep slopes. In many locations, the new snow is still bonding poorly to the hard ice crusts, and it may be possible to trigger a soft slab, especially in wind loaded areas. With both direct and filtered sun likely today, rapid warming of the surface snow could increase the possibly of triggering a sluff or shallow slab on steep slopes.

Lurking deeper in the snow pack, like chronic delinquents that won’t stop causing trouble, are the persistent faceted weak layers. On sunny slopes, collapsing in facet/crust sandwiches has been responsible for several recent avalanches. On shady, northerly through easterly facing slopes, the culprits include recrystalized graupel, several different layers of facets, and a thin ice crust.

All recently reported slides have been on slopes of 35 degrees or steeper, and I would consider all steep slopes suspect. If you do venture onto slopes steeper than about 35 degrees, access their stability and realize human triggered avalanches are possible.

The Uinta Area Mountains probably have a higher avalanche danger than the neighboring Wasatch mountains. Field work yesterday confirmed there was a major natural avalanche cycle Sunday through Wednesday of large, hard slab avalanches. The slides were generally above 10,000’, on steep, rocky wind loaded slopes and up to 4’ deep and 500’ wide. People traveling in the Uintas should use extra caution and avoid steep slopes.

Bottom Line (SLC, Park City, Ogden and Provo Area Mountains):

The avalanche danger is MODERATE on slopes facing north, east, south and west, which are steeper than about 35 degrees, and above about 9,000 feet. Moderate means human triggered avalanches possible. Sluffs and soft slabs triggered within the new snow have the potential to pull out layers of old snow, creating larger more dangerous avalanches. Slopes less steep than about 35 degrees have a generally LOW danger.

Western Uintas – call 1-800-648-7433 or click here for weekend and holiday forecasts.

Mountain Weather:

A broad, upper level trough will persist over the Great Basin through Saturday, with very weak imbedded disturbances moving through. Today, there will partly cloudy skies, with occasional light snow flurries. Highs will be in the mid teens at 10,000’ and the mid 20’s at 8,000’. Winds will remain light, less than 10 mph, from the northwest. Mostly cloudy skies and a few snow flurries tonight, with light northwest winds and lows near 12. A ridge will develop over northern Utah Sunday through Tuesday, putting the Wasatch under a drier, warmer southwest flow.

General Information:

Wasatch Powderbird Guides will be flying in the Silver, Days, Cardiff and White Pine drainages, with a home run in Grizzly.

To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, please leave a message on our answer machine at (801) 524-5304 or 1-800-662-4140, or email to [email protected] or fax 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.

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

Thanks for calling!

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National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

http://www.avalanche.org/usdanger.htm