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 21, 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 21st 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 Simmons Flexi-ski of Providence.

Current Conditions:

Cloud-cover and cold temperatures kept the deep powder nice and fluffy on most slopes, especially up high.  Upper elevation slopes picked up around two feet of snow over the weekend and another 6-8 inches of light fluff overnight and today.  The Tony Grove Snotel reported 2 inches of water in the snow over the weekend and 3/10th of an inch in the last 24 hrs. Today we found excellent "white smoke" or classic Utah powder on all aspects above about 8000', with the snow even on south facing slopes still fluffy in the late afternoon.  Trail-breaking in the shin-deep powder is arduous, and if you ride up into the higher mountains expect to expend some energy digging out stuck sleds, especially if you spin your track into the sugary snow beneath all the fluff.   As a ridge of high pressure builds over the region, temperatures will begin to rise, and all the new snow on sunny slopes and at lower elevations will quickly turn to sticky and sloppy mush.

Snow and Avalanche Conditions:

 Lots of natural loose and soft slab avalanches occurred over the weekend on steep slopes, but with the exception of a few freshly formed ridge-top drifts, the instabilities within the new snow have largely settled out.  There are still some steep slopes where you might trigger a slab avalanche stepping into older snow.  This afternoon we found one of these slabs lurking on the steep east face of Gog in Upper White Pine Canyon .  As the third and final skier to descend the upper elevation 40+ degree east facing slope, I didn't really expect to trigger an avalanche, but I did.  I caught a peripheral view of the slope fracturing beside me and was able to escape to the side and off the moving slab.  I yelled warnings to my partners, who despite being safely out of the direct line of the descending avalanche, crouched for cover and gripped tree branches as the slide ran down the steep chute beside them.  The unintentionally triggered avalanche was about 40 feet wide and 18 to 20 inches deep at the crown, running approximately 500 vertical feet.  It failed on sugary or faceted snow just under a thin sun-crust, which formed a week ago on March 14th and was then buried by the subsequent productive week's-worth of snow, (containing well over 3 inches of water). (see profile)

  As powder-laden slopes are warmed by the powerful springtime sun and seasonally climbing  temperatures, the surface snow will quickly become saturated and wet avalanches will become the primary concern on steep slopes in the region.  If you notice spontaneous roller-balls or natural point-release avalanches, it's time to move to a more shady or higher elevation slope.  Although generally manageable, moist point release avalanches may entrain significant quantities of snow, especially on long slopes and might present an obvious danger to anyone in their path.  In some cases, especially on some upper elevation easterly facing slopes, the weight of wet point-release avalanches involving moist surface snow over-running steep slopes below might  trigger a deeper more dangerous slab avalanche.

Bottom Line:

There's a MODERATE danger and you could trigger avalanches on some slopes steeper than about 35 degrees in the backcountry. Wind-drift and slab avalanches are possible on upper elevation slopes facing northwest through east, and wet avalanches will become more likely with daytime heating at lower elevations and on sheltered sunny slopes.  The danger of wet avalanches could become more widespread in the coming days as warming continues through the end of the work-week.

Mountain Weather:

The stormy weather is done for the time being, and a high pressure system will set up over the region through the coming weekend.  Temperatures are likely to rise drastically in the next few days, with Friday looking downright hot.  South winds will pick up on Saturday ahead of the next of the March snowstorms.

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.