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

Tuesday March 7, 2006

Hello, this is Toby Weed of the Forest Service Utah Avalanche Center with your Logan area backcountry avalanche and mountain weather advisory.  It's Tuesday March 7th at 9:30 pm.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Backcountry Access Inc.

Current Conditions:

You'll be able to find decent powder conditions at higher elevations, especially on slopes facing the  northern third of the compass.  But, the sun got onto south and east facing slopes this morning, and by afternoon, a thin breakable crust developed.  Powder riding and turning conditions are pretty good on shady terrain, but you can still feel crusty snow underneath in most areas.  Last night's storm dropped a quick foot of snow at the upper elevations, with Tony Grove reporting an even inch of water.  Another inch fell this afternoon and two more are forecast for tonight.  Thankfully, the winds diminished with last night's frontal passage, and it was pretty calm in the mountains today.  As soon as wind-speeds increase, drifting will occur.

Snow and Avalanche Conditions:

The sun came out this morning, and it's seasonal high angle warming power began to affect the fresh snow on sunny slopes. I noticed a few wet point-release avalanches in the Tony Grove area when I arrived at about 10:30.  Thinking I might find some more, I zoomed through the flats and around the ridge, racing under the east face of Magog.  Less than a minute after arriving at a good spot to view the sunny face, I watched as a sizable natural slab avalanche spontaneously started and ran down the slope in full view right in front of me.  I restarted my sled and fumbled with my pack in search of my camera, but the avalanche stopped before I could get an action shot.  Upon further investigation, I've come to the conclusion that a wet point-release avalanche triggered by a chunk of cornice falling off the summit cliffs, overran wind-drifted snow below, and triggered a much broader soft slab avalanche. The one-foot-deep new snow slab avalanche on a 40+ east facing slope was around 100' wide and ran over 500 vertical feet down the face.  The slab failed at the interface between last night's and Friday night's snowfalls.  At the crown, I could see a weak layer consisting of small sugary or faceted crystals on top a thin sun-crust formed on Sunday.

I expect that the new snow instability settled out on most slopes today, but you still might trigger  similar avalanches on steep upper elevation slopes facing northwest through east.  Previously, persistent strong southerly winds built deeper and more dangerous drifts or hard slabs near ridge-tops.  Some built up on lasting weak layers, and you might trigger one of these on one of a few very steep slopes at upper elevations in the region.  With lots of powder available, the wind is my biggest weather concern, and it may pick up on Wednesday afternoon ahead of the next incoming storm.  By late in the day, new drifts will be forming, and some could be sensitive to your weight.  Southwest winds are forecast to be fairly strong Wednesday night, and substantial westerly winds will accompany heavy snowfall of Thursday.  I expect the avalanche danger to rise accordingly.

Bottom Line:

There's a MODERATE danger and you might trigger avalanches on slopes steeper than about 35 degrees in the backcountry.  Larger hard slab avalanches are possible on some very steep upper elevation slopes that recently received large amounts of wind-drifted snow.  The avalanche danger is likely to rise by Thursday, with high winds and heavy snow in the forecast.

Mountain Weather:

We could get a couple inches overnight tonight as a storm passes to our south.  Northwest ridge-top wind-speeds are forecast in the teens. Southwesterly winds will increase Wednesday night ahead of a vigorous storm scheduled for Thursday, which could bring significant snowfall.  More storminess is on tap for the upcoming weekend and well into next week.

General Information: 

If you're confused by some of our avalanche terms check out the cool new Avalanche Encyclopedia. 

For a list of recent avalanches in  the regional backcountry go to Avalanche List.  Snow nerds, check out the new Snow Profiles page.  Check out our Images Page for pictures of recent local avalanches.

Please send backcountry observations to [email protected] or leave a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We really want to hear from you, even if you think your observation is unimportant.    The information you provide may save lives...

This advisory will expire on Wednesday night. I will update it again on Thursday night.

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. 

National Weather Service - Salt Lake City - Snow.