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

Thursday January 10, 2008

Hello and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  It’s Friday January 11th, and it’s about 7:30 in the morning.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Simmons Flexi-ski of Providence.

             Current Conditions:

The local mountains picked up another healthy shot of snow, with the Tony Grove Snotel reporting 1.7 inches of water equivelent gain since Tuesday afternoon and the Ben Lomond Peak Snotel showing an increadible 3.7 inches in the same time frame.  There’s now 78 inches of total snow on the ground at Tony Grove, with the top 3 feet or so consisting of soft powder.  A west wind kicked up in the last couple hours at the Campbell Scientific weather station atop Logan Peak, now averaging over 20 mph with gusts in the 30s. Its 5 degrees this morning at 9400’.   The deep deep snow will probably continue to keep most of us out of trouble.  You’ll find difficult trail breaking conditions, and expect to get your sled stuck multiple times if you try to punch it up through untracked routes to upper elevations.

            Avalanche Conditions:

I noticed a couple wind slab avalanches low in Logan Canyon yesterday afternoon, and I observed cracking in the upper layers of the new snow.  With the exception of some lingering wind slabs that could be sensitive to your weight, I expect instabilities within yesterday’s new snow to have mostly settled out by today.   The moist snow from last Saturday set up solidly, like plaster capping underlying weaknesses, and now we’ve got around 3 feet of powder stacked up on it. 

The additional weight from yesterday’s storm might be just enough to put some slopes over the edge.  I’d not be surprised to see evidence of a few full-depth natural avalanches on slopes cursed by faceted snow near the ground and overloaded by all the new water weight.  The good news is that the Deep Slab instability caused by faceted or sugary snow near the ground is now so deeply buried in many places that your weight alone is probably not enough to activate it.  The bad news is that you might not get any tell-tail signs of danger until you actually trigger the slab from a shallow spot.  Potential large hard slab avalanches could be several feet deep, very broad and deadly. Possible trigger spots include rocky or generally shallow areas, like cliffy lower elevation areas or upper elevation slopes scoured by previous winds.  Possible triggers include overrunning smaller wind slab avalanches, additional loading from heavy snow and wind drifting, cornice falls, and unwary Humans.

Increasing winds and additional snowfall today will cause a rising danger.  Watch for freshly formed or building wind slabs, and avoid them on steep slopes at all elevations.  Be wary of the dangerous combination of faceted snow near the ground and recent drifting on slopes with shallow overall snowcover at mid and lower elevations.

               Bottom Line:

  There’s a CONSIDERABLE danger and you could trigger wind slab avalanches at any elevation on steep slopes exposed to drifting in the backcountry.  Deadly triggered deep slab avalanches are also possible on slopes with existing weak snow near the ground, mainly in exposed upper elevation terrain.  Increasing winds and snowfall today could cause the danger to become more widespread.  Today, avalanche training and experience are essential for safe backcountry travel.

               Mountain Weather:

  Clouds thickened overnight as the next storm in this year’s so-far very productive series is quickly moving into the area.  The National Weather Service has issued a Snow and Blowing Snow Advisory for the mountains around Logan from 11:00 this morning through tomorrow afternoon. Today we’ll be in an often productive warm air advection flow, with the cold front scheduled to arrive sometime tomorrow morning.  A bit more snowfall is expected on Saturday afternoon, before a short-lived high pressure system builds into the region, bringing hazy conditions to the valleys for Sunday and Monday.  Models are still in disagreement about potential storminess around Tuesday.

General Information:

I will give a free avalanche awareness talk for snowmobilers at Renegade Sports tonight at 7:00.

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.

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.