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

Sunday, March 11, 2007 7:30 am
Good morning, this is Drew Hardesty with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Sunday, March 11, 2007 and it’s 7:30 in the morning.

Current Conditions:

Skies are clear and winds are generally light from the northwest. Overnight lows were in the mid-to-low 20’s, but it looks like it’ll be the last night for a decent refreeze for the next couple of days. Mid-and upper elevation remain excellent, with off aspects and lower elevations crusted.

Snow and Avalanche Discussion:

Gustier a.m. conditions produced a host of garden-variety soft slabs intentionally and unintentionally triggered by backcountry skiers in upper elevation north through east facing terrain. Most were 6-10” deep and 30-40’ wide, with one in Days Fork breaking out 150’ wide. We heard about six of these scattered across the range and give it another day, and many will become less sensitive and widespread.

Of greater interest, however, were the two and perhaps three larger hard slab avalanches stepping into old snow.  The first, which may have been just a new-snow-only avalanche, involved a snowmachiner in the upper American Fork drainage.  He triggered a slab near a rocky outcrop 1-3' deep and 50' wide in steep Mary Ellen at 11,000'.  Apparently his machine ragdolled a few dozen times with the debris, but the rider reportedly came out ok.  Over along the Park City ridgeline above Lake Desolation, a very experienced backcountry skier triggered a hard slab 1-3' deep and 40' wide on a steep north to northwest facing roll at 9600'.  He hit a thinner part of the slab pulling out the pocket, which incidentally was adjacent to the large natural that pulled out on the 2nd.  Far luckier was the party in the upper starting zone of the Cabin Run on Gobbler's Knob, a classic northwest facing slope at 10,100'.  A party of three collapsed the slope and remotely triggered a hard slab 1-3' deep and 300' wide, failing on very weak faceted snow in terrain holding a thinner slab and weaker basal depth hoar.   One of our observers had been in the terrain an hour earlier and spooked from the snow stability tests, left the area for lower angled terrain.

While likely less sensitive than yesterday, today's rapid warming may still enhance human triggering of the newer storm snow and soft slab avalanches in upper elevation north through east facing terrain.  Same story for the hard slab avalanches into older snow.  They'll be most suspect in steep rocky terrain or in areas with a thinner snowpack on the shady end of the compass.  Simple probe or ski pole tests will give some clue to the structure here.  With the natural cycle long done, it's becoming even more critical to dig snowpits and perform stability tests to get more information. 

Daytime warming, light winds, and a high sun should have the new snow moving well when saturated on the steep sun-exposed slopes.  Shallow wet slabs up to 10" may be triggered from other wet sluffs or human activity.

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

The danger of wet sluff and slab avalanches may rise to CONSIDERABLE today with daytime warming on the sun-exposed slopes.  The danger of triggering a remnant soft slab or deeper slab remains MODERATE, although the consequences for the two are miles apart.  Remotely triggered slides remain possible.

Mountain Weather:

Sunny skies, light northwesterly winds, and rapidly rising temps into the mid-40's at 8000' and mid-thirties at 10,000'.  Even warmer tomorrow.

Announcements:

Yesterday, the Wasatch Powderbird Guides were grounded due to weather, but today will be operating in Snake Creek, AF and Cascade with a home run in White Pine. The other ship will likely be in Lambs and the Sessions. With questions regarding their areas of operation call 742-2800.

The UAC and ACE are offering a day long Women’s Avalanche Awareness class at Alta on March 22^nd covering beacon use and basic safe travel, terrain and snowpack information, for a nominal fee. For more details go to: www.altaarts.org.

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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.
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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.

I will update this advisory by 7:30 on Monday morning, and thanks for calling.