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 January 9, 2007

Hello, this is Toby Weed of the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  It's Tuesday January 9th, and its 9:15 pm.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Backcountry Access.

Current Conditions:

Early Monday morning warm, moisture-laden clouds, driven by northerly winds over the upper elevations of the Central Bear River Range formed a widespread brittle rime crust. (click here for a description of rime) It's the kind of shin-breaker crust, capping lighter snow that I became accustomed to and very tired of growing up in New Hampshire.  The hateful crust gets thicker as you go higher up in elevation and plagues all slopes clear to the highest summits; at least in the northern part of the range.  Now the only enjoyable soft snow, spared by the freezing sleet is down at lower elevations and in the deep dark trees. 

Avalanche Conditions:

The rime-crust, relentless northerly winds, and cold temperatures appear to have locked up most instabilities from the weekend's windy storm.  On most slopes I looked at today, it would take a substantial trigger to initiate an avalanche. I noticed evidence of a few smallish natural wind slab avalanches at upper elevations, which probably occurred sometime late Saturday.  These failed on a layer of light stellars, a weak layer that heals or stabilizes pretty quickly.   Avalanches are generally unlikely in the backcountry, but there are still some places where you might trigger an old wind slab.   I'm mostly concerned about  wind drifted slopes at mid-elevations where stiff slabs formed over the weekend, in some cases on top of very rotten and weak snow.  I received several observations in which you reported widespread collapses or whoomphing noises. These mostly were experienced between 7500 and 8500' and in areas with a fairly shallow overall snowpack.  If you trigger audible collapses, the snow is telling you that it's sitting in an unstable state.  A slab is resting on a weak layer, and your weight is enough to cause a compression failure. 

   I expect some fairly strong winds on Wednesday in advance of the incoming storm.  In upper elevation areas like the Naomi Peak Area, where the rime crust has all the powder sealed up, there is no way drifting will occur now.   But, I'm still unsure of the aerial extent of the crust, and there may well be unaffected areas with soft snow where fresh drifts may build up during the day.  The impermeable crust is likely to cause problems once it's buried.  In places I noticed frost crystals or surface hoar on the surface, and entire slopes are smooth and slick, like giant tilted pool-tables.  In other places the rime deposits created a rough, course-grained sandpaper-like surface. 

Bottom Line:

There's generally a LOW avalanche danger, and avalanches are unlikely on most slopes in the region.   Exceptions to this and a MODERATE danger can be found on very steep previously or recently wind drifted slopes in areas without the rime-crust, at mid-elevations, and on slopes with a shallow overall snowpack; with around three feet or less of total snow.  Triggered avalanches are possible in these areas, and you should use good snow assessment and safe travel techniques.

Mountain Weather:

It will be warm and windy in the mountains on Wednesday, with southwest winds averaging in the upper twenties and a high temperature of 38 degrees forecast for 9000'.  A very cold and productive Pacific storm will move into the region and snowfall will begin late Wednesday.  Thursday definitely looks like a goggle day, and 1 to 2' of accumulated cold snow is likely by Friday morning.  Another burst of weather is forecast for the later part of the coming weekend.

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.  And they're offering a Level 1 Avalanche Class which is scheduled to begin on Thursday January 26th.

For cool pictures of some of 2006's avalanche activity, including last week's avalanches, visit our Images Page.

These advisories are updated on Tuesday and Thursday evenings and weekend mornings by about 7:00.  This advisory will expire on Wednesday evening.   I will issue an updated advisory on Thursday 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.