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Utah Avalanche Center in Logan

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 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

Saturday February 17, 2007:

  Hello and good morning, this is Toby Weed of the Forest Service Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  Itís Saturday  February 17th, and itís 7:20 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.

Bottom Line:

This weekend there's a CONSIDERABLE avalanche danger in the backcountry, and you could trigger dangerous wind slab avalanches on any slope steeper than about 35 degrees with recent deposits of drifted snow.  The danger is greatest in areas that picked up significant new snow, above about 8000' in elevation, and on slopes facing the northeastern half of the compass.   Rapidly rising daytime temperatures this weekend will likely cause a more widespread danger of both slab and moist point-release avalanches, and some may naturally occur in the heat of the day.

Current Conditions:

The Tony Grove Snotel picked up 1.7 inches of water in 7 or 8 inches of snow from Thursday night's storm.  Strong westerly winds raked the high country building drifts in both expected and unexpected places.  Sadly, all the heavy, wind-blasted new snow from Thursday night capped the nice fluffy powder that had been piling up at higher elevations.  The rime-crusted heavy new snow we were wallowing around in yesterday came in seriously inverted or upside-down, (with light snow under mashed potatoes), and extremely tedious trail-breaking offered little reward with unforgiving if not challenging turning conditions.  It was quite easy to loose momentum on even small hills, and by spinning the track down into sugary basal snow, you'd quickly bury yourself in a nasty hole.  Hopefully and quite possibly, clear atmospheric conditions might have helped to revert and improve the new snow.

Avalanche Conditions:

In addition to causing a danger of moist point-release avalanches on sunny slopes, rapidly rising daytime temperatures this weekend could create an increasing danger of slab avalanches.  Warmth speeds up the creep rate of the slabs often causing natural avalanches, or worse, increases sensitivity to triggering...

Wind slabs will continue to present the most obvious avalanche danger.  Extensive drifting occurred on Friday along exposed ridges and down at lower elevations. Significant slabs formed in lee-slope starting zones, and vertical cross-loading  built drifts along exposed sub-ridges and around terrain features like gully walls, tree bands and rock out-croppings.  Wind drifts are not confined to terrain features.  Whenever we get a combination of heavy snowfall and strong or sustained winds, large loads of wind-blown snow can be rapidly deposited over vast areas and often well off of the exposed ridge-lines.

We noticed a couple recent natural avalanches on steep north and east facing slopes yesterday, but were somewhat surprised not to see more.  All the building blocks for avalanches are in place, now with a significant new slab and existing very weak buried layers.  Given the conditions, we were far to scared to test any steep wind-drifted slopes, but we watched in amazement as many that we wouldn't dare go near were successfully machine tested and appeared to stay in place.  I know most of you are now carrying and have practiced extensively with your beacons, probes, and shovels, but you need to remember not to expose more than one person at a time to avalanche danger on steep slopes.  We watched in horror yesterday as two or sometimes three of you at at time tested obvious avalanche starting zones... Remember, your buddy can get his sled unstuck himself and without your help on a steep slope.

Mountain Weather:

   A short-lived high pressure system will build over the region for the weekend bringing a break in precipitation and warm daytime temperatures in the mountains.  Tomorrow will be a few degrees warmer than today, but building clouds and south winds will usher in the next wave of moist Pacific storminess.  6 inches to a foot of accumulation is possible at higher elevations on Sunday night.

 General Information:

Check out the recently-released Media Page, which shows the current and forecast danger for our coverage areas across the state.

The Utah Avalanche Center compiled a good collection of photos from this week's avalanche cycle in the Wasatch Range.  Click here to visit this season's photos.  Check out photos of avalanches in the Logan Area on our images page.

Please send me an e-mail at [email protected] or leave me a message at 755-3638 if you see evidence of recent avalanche activity or avalanches in the backcountry.  The information you provide may save lives...

  I will update this advisory again Sunday morning.

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.