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/

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Logan area Avalanche advisory

Sunday March 4, 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.  It’s Sunday March 4th, and it’s 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 Black Diamond.

Current Conditions:

A low cloud deck over the Logan Area Mountains kept temperatures mild overnight.  But clouds should dissipate by mid morning and mountain temperatures will rise significantly under a ridge of high pressure.  In the past week, more than four feet of snow piled up in favored parts of the Bear River Range, and we can see evidence of numerous giant and unsurvivable avalanches in the mountains surrounding Cache Valley from downtown Logan.   There's 90 inches on the ground at the Tony Grove Snotel site containing 79% of average water equivalent.   Mountain temperatures are hovering around twenty under cloudy skies this morning.   Clearing skies, rapidly rising temperatures,  and a light southeasterly breeze are in the forecast for today.

Avalanche Conditions:

  Even though the weather will be pleasant today, with sunshine and warming temperatures, dangerous avalanche conditions still exist on many steep slopes.  Natural and triggered avalanches will become more likely as slopes with tons of recent new snow are heated significantly for the first time. While in most cases the now fairly deep slab is probably somewhat difficult for a person to impact, if you hit the shallow part of a slope just right you could still trigger a deep and very dangerous hard slab avalanche releasing on a persistent buried weak layer.   Loose moist avalanches overrunning slopes with deep instabilities are also likely triggers today.   Sheltered sunny slopes will heat up significantly today, which will increase the danger of both slab and moist avalanche activity. 

  Twice this week, very strong westerly winds and lots and lots of readily transportable snow caused widespread natural avalanches in the region.  While deep powder now obscures the evidence of most of this week's avalanche activity, several of the most recent natural avalanches (some visible from Cache Valley) stepped down into early season snow or the ground and definitely fit into the huge and unsurvivable category. Topping the local news are two natural monsters that furiously descended into Providence Canyon early Friday morning. "The Big One" ran almost 3000' vertical feet and hit the well-traveled Providence Canyon Road with tons of stick-filled debris, and First Waterfall Hollow pulled out full width running around 2500' and slamming the Rock Quarry.  Both avalanches encompassed ~100% of the paths, and stepped down to weak sugary snow near the ground with crown lines averaging 4 to 6 feet deep and many hundreds of feet wide. (photos) ****

Bottom Line:

Warming temperatures today and deeply buried persistent weak layers will cause a CONSIDERABLE danger on steep slopes in the backcountry.   Rapid solar warming will cause an increased danger of both slab and moist loose avalanches, initially on sheltered sunny slopes.  Human triggered deep hard slab avalanches are possible on numerous slopes steeper than about 35 degrees and some large natural avalanches are possible.    Remotely triggered avalanches are also possible in some areas.    If you're not extremely confident with your route finding and avalanche avoidance skills, you should stay out of backcountry avalanche terrain this weekend.

 Mountain Weather:

A high pressure system will build over the region, low clouds will dissipate, and temperatures will rise significantly in the mountains.  Mountain high temperatures could reach the mid-forties today.  Mild mountain temperatures will persist into the middle of next week, when a couple weak-looking impulses will bring unsettled weather and snow showers to the region.

General Information:

For more information on last week's accidents from the Utah Avalanche Center, go to accidents

Check out photos of last week's avalanches in the Logan Area on our images page.

Go to the Avalanche Encyclopedia if you have any questions about terms I use in the advisory.  I also recommend the recently-released Media Page, which shows the forecast danger for our coverage areas across the state.

Please e-mail me at [email protected] or leave me a message at 755-3638 if you see or trigger avalanches in the backcountry.  The information you provide may save lives...

    This advisory will expire on Monday morning.  I will update it again on Tuesday evening.

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.