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

Monday, December 31, 2007 7:30 am
Good morning, this is Bruce Tremper with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Monday, December 31, 2007 and it’s about 7:30 am.

Special Avalanche Advisory:

A Special Avalanche Advisory has been issued for the Uinta Mountains where a HIGH avalanche danger exists. High wind and heavy snow has overloaded an especially weak, pre-existing snowpack. Avalanches will be large, deep and persistently unstable. Backcountry travelers should avoid all slopes especially ones that face the north and east quadrants of the compass at elevations above about 9,500’.

Current Conditions:

Yesterday was a wild day in the mountains with very strong west to northwest winds, heavy snow and widespread avalanche activity. Very difficult trail breaking in upside down snow and poor visibility helped to limit backcountry avalanche incidents. The winds blew as hard as 55 mph, gusting to 80 on the most exposed peaks. 8-18 inches of snow fell yesterday with storm totals of 2-3 feet over the weekend. The wind has decreased a little this morning, but it’s still blowing hard from the northwest 20-40 mph with stronger gusts. Ridge top temperatures have plummeted to zero. It’s Frostbite City at 11,000’ with winds blowing 40 mph, gusting to 70 and temperatures are -6. But we expect winds to decrease today. Trailbreaking will continue to be hard in slabby, deep snow. Bring equipment with a lot of surface area.

Avalanche Discussion:

Ski area control work reported widespread, sensitive wind slabs at almost all aspects and elevations and many natural avalanches occurred in the backcountry yesterday within the new snow. One experienced backcountry skier backed off the steeper slopes in lower Butler Fork in Big Cottonwood Canyon and on his way out, triggered an 8 inch deep, 100’ wide, wind slab that buried the trail 4’ deep (PHOTOS).

I expect that the snow has settled a bit overnight, especially with the colder temperatures, which means that we may not see many natural avalanches today, but there’s still plenty of human-triggered potential on any slope approaching 35 degrees or steeper, especially slopes with recent wind deposits. Since the wind affected nearly all terrain, you will find these wind-deposited slopes from near the valley floor to the tops of the mountains and on all aspects. The slabs are stiff, heavy and thick, so any avalanches you do trigger today could easily be tree-snappers and hard to survive.

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

The danger is CONSIDERABLE on any slope approaching 35 degrees or steeper, especially slopes with recent wind deposits. This means that human triggered avalanches are probable. There is still a possibility of lingering, deep-slab potential shady slopes facing northwest, north and northeast, above about 9,500’, where it is possible to trigger a deep, dangerous slide releasing near the ground.

Be advised, there is a HIGH avalanche danger in the Uinta Mountains which has a much weaker pre-existing snowpack.

Mountain Weather:

Ridge top winds will diminish today but you’ll still need a down coat, mittens and a face mask. Winds should diminish from 30 mph from the west to around 15 mph and ridge top temperatures should remain in the single digits and near zero on the highest peaks. There’s still a few lake-effect squalls lingering this morning but we should have partly cloudy to clear skies for much of the day.

On New Year’s Day, the temperatures should warm dramatically to near freezing and we will be in a strong high pressure ridge for most of the week. Then it looks like another strong storm for next weekend.

Announcements:
UDOT will conduct avalanche control in Little Cottonwood Canyon this morning and they expect to reopen the road by about 8:30 am.

Today the Wasatch Powderbird Guides will fly in the Session Mountains, Lambs Canyon and American Fork. For more information, call them at 801-742-2800.

For an avalanche education class list, updated 12/22/07, 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.

Brett Kobernik will update this advisory by 7:30 on Tuesday morning.