Logan Avalanche Advisory

Forecaster: Toby Weed


Danger by aspect and elevation on slopes approaching 35° or steeper.
(click HERE for tomorrow's danger rating)

Danger Rose Tutorial

You'll find a level 3 or Considerable danger on drifted slopes at upper and mid-elevations in the backcountry. Dangerous avalanche conditions exist and triggered wind slab avalanches are probable in terrain exposed to wind drifting and on slopes approaching or steeper than about 35 degrees. Wind slab avalanches could be triggered remotely from a distance, or worse, from below. You'll find safer conditions and a level 1 (or Low) danger in sheltered and lower elevation areas. Careful snowpack evaluation, cautious route finding, and conservative decision making are crucial in steep drifted terrain today.


The Tony Grove Snotel at 8400' reports 5 or 6 inches of heavy and moist new snow from yesterday evening and overnight, containing 8/10ths of an inch of water. Its a balmy 28 degrees this morning, and there's 77 inches of total snow at the site containing 141% of average water for the date. The Campbell Scientific weather station at 9700' on Logan Peak is back on line, but the wind sensor appears to be rimed again this morning after the winds shifted from the northwest overnight. It's 21 degrees at the mountain top installation.


I intentionally triggered a nice wind slab late yesterday afternoon with a deep turn in drifted mid-elevation terrain on the Steam Mill/White Pine Canyon Ridgeline. The stiff wind slab avalanche on a northeast facing slope at around 7500' in elevation was around a foot deep and a hundred feet wide, but it didn't run far in fairly low angled terrain. A bit lower on the same ridge, I remote triggered at least two more similar pockets from a good distance away....(see report)


      Over the next 24 hours.

Stiff drifts and wind slabs built up in exposed terrain over the last few days, and many of these formed on top of weak layers consisting of preserved frost of surface hoar, sugary faceted snow, and/or thin rime-crust layers. The fresh snow from last night will also be easily drifted into deposition areas and avalanche starting zones Watch for and avoid fresh and forming drifts near ridge lines and in and around terrain features like gullies, cliff-bands, and sub-ridges. Triggered wind slabs 1 to 2 feet deep are likely today, and could be triggered from a distance or from below....


      Over the next 48 hours.

In many areas, the new snow looks to have nicely preserved weak surface snow consisting of insidious frost or surface hoar and small grained faceted snow on many slopes. These notorious and tricky persistent weak layers have a very nasty reputation, and are known to be the culprit weakness in the majority of avalanche accidents in the U.S. and Canada... A preserved surface hoar layer is particularly evil, in that avalanches running on it often occur on slopes less steep than other types of avalanches, and slopes can remain in a balanced unstable state for a good while after their initial loading.....

Weak surface snow is widespread in the region and preserved by a few inches of light snow, and it looks as though we may be set up for a problem with tricky persistent slabs as we plow through the first month of 2011...


We'll see a bit more snowfall in the mountains this morning but little in the way of accumulation, as a moist and mild northwest flow sets up over our region.... Periods of light snowfall are likely in the next few days, with increasing westerly winds on Sunday ahead of a slightly more productive shot of snow accumulation Sunday afternoon into Monday......


You can view a photo summary of last year's avalanche activity in the Logan Area HERE

I will be update this advisory in the mornings on Monday, Wednesday, Friday, and Saturday, and on other days if backcountry avalanche conditions warrant...

You have the opportunity to participate in the creation of our own community avalanche advisory by submitting avalanche and snow observations. You can also call us at 801-524-5304 or Toby at 435-757-7578, or email by clicking HERE

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This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.

This information does not apply to developed ski areas or highways where avalanche control is normally done.  This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.

This advisory provided by the USDA Forest Service, in partnership with:

The Friends of the Utah Avalanche Center, Utah Division of State Parks and Recreation, Utah Division of Emergency Management, Salt Lake County, Salt Lake Unified Fire Authority and the friends of the La Sal Avalanche Center. See our Sponsors Page for a complete list.