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

7:30, Friday February 8, 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 February 8th, at 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 EK USA.

Current Conditions:

Yesterday’s incessant and dangerously strong west winds diminished significantly overnight and switched around from the north.  But the damage is done…In a few hours, thousands of acres of fine powder from a two-week-long freight-train of cold storms turned into a highly varied and wind-hammered mess.  You’ll be able to find all kinds of challenging wind affected snow in the backcountry today, with wind crusts, thick drifts, and large cornices at all elevations and vast windward slopes now scoured to the bone.  Yesterday’s storm also produced heavy, dense snow, which stacked up on the fluffy powder causing inverted snow, (heavier on top).  This makes for difficult traveling conditions, where you have to work hard to break trail and you’re fairly likely to get your sled stuck if you get bogged down in a drift.  The Tony Grove Snotel reports an increase of 1.2 inches of water equivalent in 8 or 9 inches of snowfall over the last 24 hrs, and with 103 inches of total snow on the ground the station is at 103% of average water for the date.  It’s currently 7 degrees at the Campbell Scientific weather station on Logan Peak and there’s a 20 mph northwest wind.

  Avalanche Conditions:

  Extensive drifting caused numerous natural and triggered wind slab avalanches across the mountains of Northern Utah yesterday. Many of these took place at lower elevations, and debris stacked up on a number of mountain roadways…Yesterday’s drifting forced us to reevaluate our route, and we triggered deep shooting cracks on lower angled slopes on our retreat.  We noted a number of smallish natural wind slab releases at lower elevations in Logan Canyon, which occurred all through the day, (photos).  I would not be at all surprised to learn of large natural avalanches from yesterday, and I can’t wait to get a view of the large east facing paths in the Wellsville Range, which were quite active last weekend. (Old Logway Canyon photos)


Strong west winds yesterday drifted tons of snow into avalanche starting zones and built up huge cornices and stiff, thick wind slabs.  Heavy snowfall accompanying the wind caused extensive loading over large areas.  Today you’ll find the most substantial wind deposits and greatest avalanche danger at mid and upper elevations, under large growing cornices, and near ridge lines.  But significant drifting also occurred well off ridge tops and on exposed slopes at lower elevations where generally weaker snow exists.  Also, vertical cross-loading led to substantial wind slab formation near sub-ridges, in gullies, and under cliff bands.  The wind built stiff heavy drifts on much lighter powder that was previously on the surface, creating a truly unstable situation.  In most cases these instabilities should heal up fairly quickly, but in some areas drifts formed on slopes with buried persistent weak layers, which may result in lingering instability and future triggered avalanches.

   Bottom Line:

There’s a CONSIDERABLE danger on steep wind drifted slopes in the backcountry today, and triggered avalanches are likely on a variety slopes steeper than about 35 degrees and possible at all elevations.  Many slopes with significant recent deposits of wind drifted snow may now be hanging in a delicate balance, only needing a trigger to produce a dangerous avalanche, and continued drifting from moderately strong west winds may cause some natural avalanches in exposed terrain.  Today a HIGH danger may well be lingering on steep slopes in some areas.  Avalanche training and experience are essential for safe travel in avalanche terrain, and you should avoid and stay out from under steep drifted slopes and obvious or historic avalanche paths in the backcountry…

Warming this weekend will likely cause a CONSIDERABLE danger of wet avalanches at lower elevations……

    Mountain Weather:

Expect continuing moderately strong west winds, cloud cover, and some snow showers today, with 8000’ temperatures up in the mid-twenties.  It will warm up significantly over the weekend, and we’re likely to see a bit of sunshine tomorrow.  Mid elevation temperatures are forecast to be well above freezing on Sunday.  Warming in the next couple days is likely to cause significant problems with wet avalanches, especially at lower elevations.  Storms moving off the Pacific should split apart or stay to our north next week.

General Announcements:  This advisory will expire in 24 hours from the posting time.

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 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.