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

Sunday February 5, 2006

Hello and good morning, this is Toby Weed of the Forest Service Utah Avalanche Center with your Logan area backcountry avalanche and mountain weather advisory.  It's Sunday February 5th at 7:00 am.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Import Auto at 502 West 1400 North.

Current Conditions:

Last night's fast moving storm dropped about 6 inches on mountain slopes in the region.  Tony Grove Snotel reports about 7 inches of new snow, while Temple Fork shows around 5.  There's about 130 inches of snow on the ground at the Tony Grove Snotel site and 161 percent of normal water content.  Temperatures plummeted overnight, with readings at most stations about 20 degrees lower now than midday yesterday.  Currently it's 9 degrees at 9400 ft on Logan Peak and 20 degrees at 7400 ft at Temple Fork.  Friday and Saturday, strong westerly winds raged in exposed terrain at upper elevations.  On Friday, the gale was from the northwest and yesterday, from the southwest.  Northwesterly winds today will fuel continued snow showers in the mountains and form fresh drifts.

Avalanche Conditions:

12:00-  I just received a report of a significant human triggered avalanche in the lower part of the gut in Garden City Canyon, which occurred on Saturday.  A couple skiers triggered a loud collapse and watched as the slope 60' below them avalanched. The observer reported the slide on an east or southeast facing slope as being 1-1.5' deep and a couple hundred feet wide. This avalanche perfectly fits the profile of one which failed on a persistent buried weak layer.  Because it was low in elevation and near a canyon bottom, it's reasonable to assume frost crystals or surface hoar made up the weakness.  We've also been finding buried weak sugary or faceted snow associated with a thin sun-crust on similar slopes.  You should be watching for either problem as you are assessing the stability of any slope.

 Winds from the different directions affect different areas in the mountains differently. But, it is fair to say that the winds ripped snow off windward slopes, built deep stiff drifts in fetch areas, and loaded tons of snow into lee-slope avalanche starting zones.  Yesterday, I journeyed into the Wellsville Range took try and get a better view of a recent large natural avalanche in Pine Canyon. I'd estimate the avalanche, which occurred in the last couple days, was around 400' wide and 4 to 6' deep, running about 1750 vertical feet.  It occurred on the same slope that avalanched in a big way almost exactly a month ago, and since the snow was shallow in the slope, probably broke on weak sugary snow near the ground.  I couldn't get to the crown because of safety concerns, but I noticed evidence of numerous other recent smaller natural avalanches.  In fact, nearly every east and northeast facing path that I saw had run with new-snow wind-drift avalanches, many went well over 1500 vertical feet.

Today winds will be a factor again in a northwesterly flow.  They will build fresh drifts, which are likely to be sensitive to your weight.  Again today you should be wary of chalky looking, hollow sounding, and stiff feeling wind deposits on steep slopes.  Be on the lookout for signs of instability like audible collapses or shooting cracks.  Remember that hard slabs have a tendency to sometimes let you get well out on them before releasing.

Bottom Line:

Overall, there's a MODERATE danger on steep slopes in the backcountry.  Avalanches are unlikely in sheltered terrain, but possible on some steep wind-drifted slopes at lower and mid-elevations.  In exposed terrain at higher elevations the danger is CONSIDERABLE, with avalanches possible on many wind-drifted slopes steeper than about 35 degrees.  Avalanches on some steep slopes might step down into buried weak layers and be large and dangerous. 

Mountain Weather:

Northwesterly winds and snow showers are likely to continue through much of today before a high pressure system sets up shop for the upcoming work-week.  Winds and snowfall will gradually diminish by this afternoon.  Fair weather in the mountains and hazy conditions in Cache Valley are in-store for the week ahead.

General Information: 

We will offer a free avalanche awareness talk open to the public at the Trailhead on Wednesday evening, February 8th at 7:00.

For a list of our upcoming classes and awareness talks, go to our Education page . For a list of recent avalanches in  the regional backcountry go to Avalanche List.  Snow nerds, check out the new Snow Profiles page.  You may enjoy our Images Page.

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 Monday morning.  Dave will try an experimental update on Monday evening.

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.