Wasatch-Cache National Forest:  In partnership with:  Utah State Parks and Recreation, Friends of the Utah Avalanche Center-Logan, and Utah State University College of Natural Resources.


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Logan area Avalanche Advisory

7:30, Wednesday January 30, 2008

Hello and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Avalanchetools.com.

We are issuing a Special Avalanche Advisory for the mountains of Northern Utah.  A powerful Pacific storm system with strong winds and heavy snow has caused widespread dangerous avalanche conditions in the backcountry.  Avoid steep slopes and obvious or historic avalanche terrain in the backcountry.

Current Conditions:

 Yet another Pacific storm slammed into the mountains of Northern Utah overnight and we picked up a decent shot of snow.  Snowfall will probably continue through much of the day in the mountains, with several more inches possible.  The Tony Grove Snotel reports 8 new inches overnight containing ˝ inch of water, while the Ben Lomond Peak Snotel shows 1.4 inches of water equivalent gain.  Its 1 degree at the CSI weather station on Logan Peak and a northwesterly wind is averaging in the teens.

  Avalanche Conditions:

Sizable natural and triggered avalanches are likely today as wind-drifted snow has now overloaded many steep slopes with existing weak layers.  The danger is greatest in areas that received the most snow overnight, like the Wellsville Range.  Clouds obscured the Bear River high country yesterday but we could see evidence of a few natural avalanches.  Of particular interest was a wind slab, which released on a mid-elevation slope facing southeast in Lower Tony Grove Canyon, (photos). Also, I triggered a couple large woomphs in an open meadow in White Pine Canyon at about 8600’ in elevation. A slab layer, made up of wind deposited snow, audibly collapsed on a layer weak sugary or faceted snow that was on the surface last week.


The probable key to today’s instability will be the presence of buried weak layers on slopes at all elevations. These may be associated with buried surface crusts, frost or surface hoar, or small grained facets. The wind caused extensive drifting and built hard and soft slabs on numerous steep slopes at all elevations.  The biggest wind deposits are likely to be found at upper elevations, near ridge tops, and on slopes facing the eastern half of the compass.  Hard and soft slabs could be over 3 feet deep and may be quite sensitive, as many formed on weak surface snow or stubborn since the cold temperatures probably locked up hard slabs. Watch for smooth chalky looking or hollow sounding drifts on steep exposed slopes and cross-loaded slabs in and around terrain features like gully walls, rolls, sub-ridges, and cliff bands. Keep in mind that normally obvious previously formed drifts may well be now obscured by last night’s fresh powder. Red flags to watch out for today include avalanches on similar slopes, audible collapses, and shooting cracks.

   Bottom Line:

This morning there’s a HIGH danger on steep slopes with recent significant deposits of wind drifted snow at all elevations in the backcountry. Significant natural and triggered avalanches are likely.  As the storm winds down this afternoon, the danger will remain CONSIDERABLE in many areas, and you could probably trigger wind slab avalanches on numerous drifted slopes steeper than about 35 degrees in the backcountry.  You should avoid travel in backcountry avalanche terrain.

    Mountain Weather:

A Winter Storm Warning remains in effect until 4:00 this afternoon, and the Central Bear River Range should pick up 4 to 7 additional inches during the day.  The next storm in this moist Pacific weather freight train will bear down on us Thursday afternoon and last through Friday…

General Announcements:

Check out photos of avalanches in the Logan Area on our images page.

Go to the Avalanche Encyclopedia if you have any questions about terms I use in the advisory

I'm very interested to know what you're seeing out there.  Please e-mail observations to me at [email protected] or leave me a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We keep all observations confidential.

The second annual avalanche awareness ride is Saturday Feb. 2nd and we’d love to see all of you there!  Proceeds help to support snowmobile specific avalanche awareness projects. Details can be found at http://www.avarides.com/

This advisory will expire in 24 hours from the posting time.

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.