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, Saturday February 23, 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 23rd, 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 Import Auto.

Current Conditions: Just a few inches fell yesterday and overnight in the Bear River Range, with the Tony Grove Snotel reporting a storm total of about 4 inches of new snow containing 3/10ths of an inch of water. The Snotel at Ben Lomond Peak picked up a half inch of water, which looks pretty shallow compared to the 16 inches reported by ski areas in the Central Wasatch Range. Across the Logan Area the fresh snow fell on a tired-out and tracked-up old snowpack and a wide variety of surface conditions including sun and wind crusts in exposed terrain and shallow, frosty, and reconstituted “loud powder” in sheltered shady areas at all elevations. The Campbell Scientific weather station on Logan Peak reports 15 degrees with light northwest winds, averaging 5-10 mph. With 85 inches on the ground, the Tony Grove Snotel holds slightly above average water content for the date, and its 23 degrees.

Avalanche Conditions:

It was an active day in the Central Wasatch yesterday with small but long running natural new snow avalanches catching a few people off guard, and one person riding with fresh debris for around1200 vertical feet. (Wasatch) No recent avalanche activity has been reported or observed in the Logan Area since last weekend, but the last windy storm on Valentine’s Day caused some fairly large and widespread natural wind slab avalanches. Most notable, a large cornice and hard wind slab release in Central Cornice Ridge, and a long running wind slab that came down to the flats near the Green Canyon access road.

Yesterday’s light snow fell with little or no wind and it now may be nicely preserving weak layers that formed on or near the snow surface during the recent high pressure. The soft, shallow, re-crystallized “powder” on sheltered north facing slopes at all elevations is what we call near surface faceted snow and it has a reputation for becoming a persistent weak layer once buried. Some slopes also sport frost crystals or surface hoar, and on many it’s capping wind or warmth crusts (snow photos).

Today the fresh snow will probably begin to stick to most of the crusty old snow surfaces, but even small new snow avalanches could pick up steam and run far and fast on a big slope.

You should watch the winds and the affects of drifting closely. A significant increase in wind speed or a change in direction could mean a rising danger of wind slab avalanches. These could run far on slick underlying crusts. It’s not a good night to camp in avalanche terrain as the danger will likely rise significantly overnight with strong wind and heavy snowfall in the forecast.

Bottom Line: This morning you’ll find a LOW danger in the backcountry and avalanches are generally unlikely. Surface sluffs and shallow soft wind slabs are possible however, and the danger is MODERATE on a few steep upper elevation slopes with the most new snow accumulation. Use good snow assessment and safe travel techniques to minimize your risk.

Strong winds and heavy snowfall overnight and tomorrow will cause the danger to rise significantly….Expect at least a CONSIDERABLE danger by tomorrow morning if the weather forecast verifies, with some natural avalanches possible.

Mountain Weather: The National Weather Service issued a Winter Storm Watch for the region for late tonight through Monday morning. Strong southwest winds will develop late tonight and continue into Sunday along with periods of heavy snow. The mountains around Logan should pick up a healthy shot of snow with this. A high pressure will build in for the first part of next week.

General Announcements:

Upcoming avalanche class: February 29th-March 1st, Avalanche Basics, USU Outdoor Recreation Center, Friday February 29th, 6:30p, Field Session Saturday March 1st, 9:00a.  ($35, Please register in advance with the ORC.)  For more information contact [email protected].

Check out the images page for photos of some of this season’s avalanches.

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.

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

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.