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, February 24, 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, February 24, 2007 and it’s 7:30 in the morning.

Special announcement: If conditions permit, UDOT will do avalanche control work in the Kessler and Argenta slide paths of Big Cottonwood Canyon today. Please avoid backcountry travel in these areas. In Little Cottonwood, early morning control work above the highway should be completed around 7:30 am.

Current Conditions:

The storm is winding down, with a few lingering snow showers in the Cottonwoods. Storm totals in the Ogden, Provo and parts of the Cottonwoods are generally around 10”, with up to an inch of water. However, upper Little Cottonwood, enjoying the northwest flow, easily double that number, coming with 26” of snow and 1.34” of water. Overnight the northwesterly winds blew in the 15 to 25 mph range, with gusts in the 30’s. Across the highest terrain, 30 to 40 mph averages were common, with gusts to 60. Winds have gradually decreased over the past few hours, and averages are less than 20 mph this morning. Temperatures have dropped into the single digits at 10,000’.

Snow and Avalanche Discussion:

Limited observations came in from the backcountry yesterday, due to poor visibility and the commendable common sense that kept most travelers in low angle terrain. There were reports of sensitive sluffing and a few soft slabs in the new snow. Cornices and drifts were becoming increasingly sensitive late in the day as the winds increased.

New snow avalanches, both sluffs and soft slabs, will be easy to trigger today, especially on steep wind drifted slopes and in areas that received the most snow. The wind drifts will be most widespread along the ridgelines, and on slopes facing east through south. But watch out for and avoid new and hidden old drifts on any steep slope, which may be well off ridgelines, around breakovers and other terrain features. Any slide triggered in the new snow has the potential to step down and break into deeper weak layers, resulting in a larger, more dangerous slide. Cornices are sensitive, breaking back further than normal. Direct sun later today has the potential to trigger loose sluffs with heating on steep, sunny slopes.

Even more dangerous will be any slide breaking on the deeply buried facets. A series of Wasatch storms over the past 2 weeks with 3 to 6” of water weight has landed on top of a Colorado like snowpack of weak facets and surface hoar, and the two don’t mix. It is getting harder to trigger slides on these facets, but once triggered these large, deep slides will most likely be unsurvivable. Recent southwest to northwesterly winds have heavily loaded slopes facing on the east side of the compass, and the danger is greatest on these aspects. It is possible to remotely trigger avalanches from adjacent slopes or below.

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

An AVALANCHE WARNING remains in affect for the mountains of Utah. Strong winds and snow have continued the CONSIDERABLE to HIGH avalanche danger, with 4 avalanche fatalities in Utah in the past week. Unsurvivable avalanches 2 to 4 feet deep can be triggered by people on slopes of about 35 degrees or steeper, or remotely triggered from adjacent terrain or below. People without expert level avalanche assessment, route finding skills and the discipline to remain on low angle terrain should stay out of the backcountry today.

Mountain Weather:

A ridge of high pressure will build over the region today, with a fast moving pacific weather disturbance approaching tonight. Today, skies will be partly cloudy to mostly sunny. The northwesterly winds will continue to decrease, and generally be in the 5 to 15 mph range, with gusts to 30 across the highest peaks. Temperatures today will reach the low 20’s at 8,000’ and remain in the single digits at 10,000’. Increasing clouds and southwesterly winds tonight, with 4 to 8” of snow possible by Sunday night.

Announcements:

Yesterday, the Wasatch Powderbird Guides did not fly due to weather and if they can fly today, they will be in Silver, Cardiff, Days, Grizzly, White Pine, American Fork and Snake Creek. With questions regarding their areas of operation call 742-2800.

Listen to the advisory. Try our new streaming audio or podcasts

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 a list of avalanche classes, click HERE
For our classic text advisory click HERE.
To sign up for automated e-mails of our graphical advisory click HERE

We appreciate all the great snowpack and avalanche observations we’ve been getting, so keep leaving us messages 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 on Sunday morning, and thanks for calling.