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

December 31, 2006

Hello and good morning, this is Toby Weed of the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  It's the last day of 2006, Sunday December 31st, and its 7:00 in the morning.  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:

You can find decent, reconstituted, powder-like snow on shady slopes at most elevations. Crusts are developing on sunny slopes at higher elevations, where it's warmer, and lovely frost or surface hoar crystals are abundant in lower elevation and shady terrain. Temperatures range from 16 degrees in Mendon to 27 degrees atop Logan Peak where a gentle west breeze turns the wind speed sensor at the Campbell Scientific weather station.  It could be well above freezing at upper elevations today.

Avalanche Conditions:

I am reflecting on a good 2006 from the snow and avalanche side of things.  I will remember the year for tons of fantastic snow and mostly stable avalanche conditions in the backcountry.  There were also some big avalanches and a few lucky close-calls in the region.  The last week of the year has also been quite interesting, with several human triggered avalanches and numerous reports of obvious clues or indications of unstable snow.  Fill-in forecaster, Dave Kikkert started things off on the day after Christmas by triggering a substantial wind slab avalanche with a cornice-drop in the Bunchgrass Area.  Snowmobilers unintentionally triggered a few smallish wind slabs in the Tony Grove Area but safely tested many steep slopes on Thursday and Friday.  For cool pictures of some of 2006's avalanche activity, including last week's avalanches, visit our Images Page.

 Of more concern is the snow stability outlook for 2007.  My fears are fed by continued reports of triggered audible collapses or heart-stopping whumphing noises.  Such a noise is a sure indication that a slab exists over weak snow, which is an unstable situation.  I've received several reports of collapses from across the coverage area, with extensive whumphing in shallow areas like Garden City Canyon near the summit of Logan Canyon, and Deep Canyon in the Wellsville Mountain Wilderness. Observers also report shooting cracks, and I've noticed a few small avalanches.  As you travel through the backcountry, pay close attention to such obvious clues to instability, and adjust your plans accordingly.

 Everywhere I look there's weak sugary or faceted snow.  At upper elevations the weakest snow can be found in fairly thin layers, while on shallow slopes, the entire lower realm of the snowpack is plagued by large cohesion-less grains we call depth hoar.  Whether a large avalanche cycle happens in January or February depends entirely on the weather.  A major storm or a series of storms will rock the canyons, and I wouldn't want to be a tree growing below a big avalanche path in 2007.

Bottom Line:

There is a MODERATE avalanche danger in the backcountry, with triggered wind slab avalanches possible on steep slopes.  As well as obvious surface drifts, you need to be wary of slopes with older, stiff deposits of wind-drifted snow, which are now obscured by a couple inches of powder. You are most likely to encounter these on north through southeast facing slopes steeper than about 35 degrees and above around 8500' in elevation.  Although unlikely, wind slab avalanches in some shallow upper elevation areas might step down into old weak snow.  The danger is LOW on the majority of sheltered and lower elevation slopes in the region.

Mountain Weather:

A ridge of high pressure will deflect a weak incoming storm, and it doesn't look like the year will finish with more than a flake or two at the highest elevations.  An inch or so is possible overnight.  Our next shot at a decent snowfall event comes around the end of the week.  It's still pretty far out but the models are hinting that it'll be a splitting storm, similar to the last one.

General Information:

The Friends of the Utah Avalanche Center-Logan will present the 3rd annual fundraiser on Friday, January 19th at the Bullen Center in downtown Logan.

These advisories are updated on Tuesday and Thursday evenings and weekend mornings by about 7:00.  This advisory will expire on Monday morning.  I will issue an updated advisory on Tuesday evening.  Logan Area advisories are accessible through the new statewide toll-free avalanche information line at, 1-888-999-4019.

Please send backcountry observations to uaclogan@avalanche.org or leave us a message at 755-3638, especially if you see or trigger an avalanche in the backcountry.  I'm a little starved for information from you these days.  Your observations are necessary, and the information you provide may save lives. 

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.