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

Tuesday March 27, 2007

Hello, this is Toby Weed of the Forest Service Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  Itís Tuesday March 27th and itís 10:00 in the evening.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Backcountry Access.

Current Conditions:

A powerful and slow moving spring storm is blasting the region with periods of heavy snow and strong west winds as I write.  The National Weather Service issued a Winter Storm Warning for tonight through early Thursday morning, and favored upper elevation areas could pick up a couple feet of snow in that time-frame.  Several inches already accumulated this evening, with around 4 inches recorded at the Tony Grove Snotel and 5 or 6 at Ben Lomond, and an additional foot is likely at both stations tonight.  Expect continued significant snowfall during the day on Wednesday, with another foot possible.  Overnight ridge top winds will be westerly in the 20 to 30 mph range, switching around from the northwest  and increasing slightly on Wednesday Mountain temperatures are forecast plummet into the mid-teens overnight and stay much colder on Wednesday.   

Avalanche Conditions:

 No significant avalanches have been observed or reported in the region recently. 

Moderately strong westerly winds accompanying periods of heavy snowfall will certainly be strong enough to form significant drifts in lee slope starting zones and around wind breaks and terrain features.  Fresh wind slab avalanches are possible on drifted slopes steeper than about 35 degrees, and the danger of will rise, with human triggered avalanches becoming probable on Wednesday with more accumulation and continued windiness.  Some natural wind slab avalanches will also be possible at upper elevations if the storm continues as forecast.  Keep in mind that anytime heavy snowfall is accompanied by strong winds, drifted snow can be deposited over wide areas, and potential wind slab avalanches may not be limited to ridge tops and normal wind breaks.  As usual you should avoid any fresh or building drifts on steep slopes.

With significant accumulations, storm snow avalanches are possible on steep slopes in more sheltered terrain.  It will be important to dig down and test the bond between the saturated old snow surface and tonightís new snow.  Sometimes a large temperature difference or other factors cause a poor bond resulting in an increased danger of new snow avalanches.  Also weak layers often develop within the new snow while itís piling up.   Not much of a problem with less than a foot of new snow, but these issues could become real concerns with a couple feet of accumulation as forecast.  As soon as the seasonally high angled sun comes out for any length of time, (most likely on Thursday), the surface snow will quickly become saturated and significant wet avalanches consisting of the new snow will be likely on steep sunny slopes.

Bottom Line:

Thereís a MODERATE danger in the backcountry, and human triggered wind slab and storm snow avalanches are possible, especially on drifted slopes steeper than about 35 degrees.  The danger is likely to rise to CONSIDERABLE during the day Wednesday on upper elevation slopes with significant deposits of new or drifted snow.  Youíll want to carefully assess snow conditions and choose conservative routes while following safe backcountry travel protocols to minimize the danger.

 Mountain Weather:

The slow moving storm will bring continued heavy snowfall to the region through the day on Wednesday.  Snowfall is likely to continue at upper elevations under a northwesterly flow until Thursday morning.  Expect clearing conditions and gradually rising temperatures on Thursday, and a gradual warm-up as a high pressure system rebuilds over the region for the weekend.

          General Information:

Check out photos of 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 Wednesday evening. I will update it again on Thursday night.

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.