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Logan area Avalanche Advisory

7:30, Friday February 1, 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 the 1st of February at 7:30.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Avalanchetools.com.

Current Conditions:

 The next box car in a freight train of Pacific Storms should depart the region today, but not before dumping a good pile of snow on the Bear River Range. Snowfall will probably continue through much of the day in the mountains, with several more inches possible.

 The Tony Grove Snotel reports a bit over a foot of new snow in the last 24 hours containing 1.3 inches of water, and there’s now 93 inches of total snow on the ground with 94% of the average water content.  The Ben Lomond Peak Snotel shows 1.9 inches of water in the last 24 hrs.  Strong south and west winds hammered exposed areas yesterday and into last night, posting sustained hourly averages in the upper thirties and gusting at around 60 mph at the CSI weather station on Logan Peak.  Its currently 8 degrees at 9400’ and a diminished northwesterly wind is now averaging in the low teens.

  Avalanche Conditions:

I’ve observed evidence of numerous natural and a few triggered wind slab avalanches in the backcountry over the last week.  Yesterday we noted some recent naturals up in Providence Canyon including one off the north face of Big Baldy that ran somewhere around 2000 vertical feet.  In the middle of the day we spied a couple small snowmobile triggered wind slabs on a south facing slope at around 8000’ in elevation, (photos).  Also of particular interest was a wind slab, which released earlier in the week on a mid-elevation slope facing southeast in Lower Tony Grove Canyon, (photos).

Yesterday’s southwesterly 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 a few feet deep and may be quite sensitive or rather stubborn. Keep in mind that normally obvious drifts are 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.


Wind-drifted snow has now overloaded many steep slopes with existing weak layers.  Although soft slabs and sluffing involving the new snow are the most likely problems you’ll find out there today, there is potential for some avalanches to step down to weak layers formed on the snow surface last week.  These now buried weaknesses consist of thin sugary or faceted layers located under brittle sun crusts on some slopes and including frost crystals or surface hoar on others. At upper elevations, we found a fairly consistent weakness18 to 20 inches below yesterday’s surface.  Avalanches stepping into old snow will be at least a couple feet deep today.  


   Bottom Line:

Natural and triggered avalanches are likely this morning, and there’s a HIGH danger on steep slopes with recent significant deposits of wind drifted and/or new snow in the backcountry.  As the storm winds down this afternoon, the danger will remain CONSIDERABLE in many areas, and you could probably trigger new snow or older wind drift avalanches on numerous slopes steeper than about 35 degrees in the backcountry. 

    Mountain Weather:

A Winter Storm Warning remains in effect until 6:00 this afternoon, and the Central Bear River Range should pick up a solid additional foot during the day today.  The next storm in this moist Pacific weather freight train will bear down on us Saturday afternoon and last through Sunday, but there are some indications that much of the energy will slide southward…

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.