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.


       The Utah Avalanche Center Home page is: http://www.avalanche.org/~uac/

             (click on) Utah Avalanche Center in Logan for our home page           


Logan area Avalanche Advisory

7:30, Wednesday February 27, 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 Wednesday February 27th, 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 the Trailhead.

Current Conditions:  The entrenched high pressure system will bring mostly sunny skies, calming winds from the northwest and warmer temperatures in the mountains today.  Currently under partly cloudy skies, the CSI weather station on Logan Peak reports 20 mph northwest winds and a balmy 25 degrees.  I’m reading 15 degrees in Logan and 18 in Mendon.  The Tony Grove Snotel picked up 2.1 inches of water in the Sunday-Monday storm, and with 94 inches on the ground the station is reading 105% of average water content for the date.  You’ll find good, if a bit heavy, powder conditions at upper elevations, but expect the newer snow to once again quickly become soft and saturated on sunny slopes.

  Avalanche Conditions:   It was another very active day in the Central Wasatch backcountry yesterday with a good number of unintentionally triggered wind slab avalanches reported, one person injured, and a handful of people getting caught in dangerous slab avalanches.  The avalanches were up to a couple hundred feet wide and as deep as two feet, stepping down to last week’s old snow surface.  Seems the initial heating was too much on drifted southerly facing slopes, and the additional weight of a person, or people, was enough to trigger these avalanches. (Wasatch report)  Yesterday in the Wellsville Range, I noticed evidence of several natural long running soft slab avalanches from the Sunday-Monday storm. 

Solar warming will quickly heat up already moist snow on sunny slopes at all elevations, and crusts that formed overnight will quickly soften.  Wet avalanches will be likely on many steep slopes in the middle of the day as the fresh surface snow is warmed and becomes saturated.   Watch for roller balling and other wet activity on similar slopes, and leave or reevaluate if the snow on the slope you’re on gets sloppy.  Snow dropping off trees, cornice falls and humans are all likely triggers of wet avalanches today.  Remember that wet snow conditions can deteriorate rapidly during the day, often making the exit from upper elevations in the backcountry more dangerous than the entrance. 

Stiff wind slabs on south facing slopes were certainly not well bonded to the crusty old snow surface, with the slab failing on isolation in test pits.  The weakness at the old/new snow interface that I found yesterday was a layer of graupel capping a solid sun-crust.  These graupel layers have a tendency to enhance facet growth, especially when they fall at the interface between warm old snow and colder new, and the weak layer currently developing is a notorious persistent weak layer.  Light snow fell with little or no wind early in the weekend, and in some areas it may have preserved weak layers that formed on or near the snow surface during last week’s high pressure. (snow photos)

Today, warming will soften wind slabs formed on sunny slopes during the weekend storm…This may make them more sensitive to human triggering.  Sun softened wind slabs might pick up steam and moist surface snow and could run pretty far today on existing smoothed in and crusted bed surfaces, especially on big slopes. 


   Bottom Line:  There’s generally a MODERATE danger in the backcountry, and triggered persistent slab and wet point-release avalanches are possible slopes steeper than about 35 degrees.   Solar warming today is likely to cause a CONSIDERABLE danger of both wet sluffs and slab avalanches on steep sunny slopes with saturated surface snow.  Use good snow assessment and safe travel techniques to minimize your risks and avoid and stay out from under steep sun-warmed slopes with saturated snow.

  Mountain Weather: A high pressure system will rule the weather pattern for the rest of the work week, with the next storm coming over the weekend.  Light winds today will again allow solar warming to heat concave south facing slopes, like solar ovens, and mountain temperatures will be a bit warmer.  Daytime temperatures will continue to rise in the next couple days.   A storm is probable late Saturday, lasting into Sunday, and another looks to be hot on its heels for next Tuesday. 

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.