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”

AVALANCHE ADVISORY

Saturday, December 15, 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 Saturday, December 15, 2007 and it’s about 6:30 am.

Current Conditions:

It’s another frosty morning in the mountains, with temperatures in the single digits to just below zero. The northwesterly winds are generally less than 10 mph, except along the higher ridges, where some stations are reporting average speeds of 20 mph. Turning and riding conditions have improved throughout the week, with a now supportable base beneath a silky mix of low density snow and recrystalized powder. Low angle slopes are fast and fun; the crusted, southerly facing slopes are the exception.

Avalanche Discussion:

There were two more human triggered avalanches yesterday in Hidden Canyon, in upper Big Cottonwood. Both were at 10,300', NW facing, approximately 3' deep, and failing on facets. Of interest, one was a large piece of "hang fire", about 70' wide by 50' long, directly above Thursday’s snowboarder triggered slide; the other, of similar size, was about 100' away. There were also reports of minor collapses in the upper Cottonwoods. (For Drew’s 12/13 Hidden Canyon accident report click HERE.)

There have been over 18 unintentionally triggered slides since the start of the month, all on upper elevation northwest, north, and northeasterly facing slopes, and all failing on facets near the ground. The pattern is clear…the weak facets are not strengthening, and you need to stay off these steep, shady slopes to avoid triggering a deep slide. Being caught in any avalanche will have serious consequences, with the potential for a dangerous ride through rocks and trees and a complete burial. Two avalanche cycles on northerly facing slopes this month are creating confusion, because some northerly facing slopes that have slid are now stable and getting tracked. But it is getting very hard to distinguish the places where avalanches have run because of various wind episodes. So instead, head to one of the numerous slopes with a low avalanche danger which have excellent riding and turning conditions

Sluffing of the weakening surface snow on steep slopes and a few isolated wind drifts along the higher ridges round out the avalanche concerns for today. These avalanches would be much smaller, but could still knock you off your feet and take you for an awful ride in the wrong place. The wind drifts may become more widespread and deeper if upper elevation wind speeds increase today.

Bottom Line:

The avalanche danger is MODERATE on steep northwest, north and northeasterly facing slopes above about 9,000’ in the Salt Lake, Park City and Provo area mountains. MODERATE means human triggered avalanches are possible. Slopes facing east, south and west and slopes less steep than about 35 degrees have a generally LOW danger, and are the place to recreate. Still, follow all safe travel procedures, especially having only one person on any steep slopes at any time. The avalanche danger is lower in the Ogden area mountains, where drifts of wind blown snow along the higher ridges is the main concern.

Mountain Weather:

A broad ridge of high pressure will be over the area for the next few days, with weak storms passing mainly to the north. This will bring partly to mostly cloudy skies to the northern mountains, with a few snow flurries possible. Temperatures will start to warm slightly, reaching the upper teens by the end of the day. Winds will be from the northwest, generally in the 10 to 20 mph range, with gusts to 25. The weather mid to late next week is looking much more interesting, with a couple storms possible.

Announcements:

Wasatch Powderbird guides will be flying recognizance without clients this afternoon in American Fork, White Pine, Cardiff, Days and Silver.

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.

Drew Hardesty will update this advisory by 7:30 Sunday morning.