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

Thursday January 26, 2006

Hello, this is Toby Weed of the Forest Service Utah Avalanche Center with your Logan area backcountry avalanche and mountain weather advisory.  It's Thursday January 26th at 8:30 pm.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from avalanchetools.com.

Mountain Weather:

The National Weather Service in Salt Lake City has issued a Snow Advisory for the region through late Friday night. Friday will be snowy in the mountains, with 8 to 10 inches of fresh accumulation possible by nightfall.  Southwesterly winds are forecast to stay in the teens along the ridge tops.  We'll get a break late Friday night and Saturday morning before the next storm-wave hits.  This one will be stronger, initially with significantly stronger southwest winds and up to about a foot-and-a-half of snowfall.  We'll see another break Sunday afternoon, but a progressive and productive weather pattern will continue well into next week.

Current Conditions:

Solar heating and strong winds this week combined to ruin the fine powder on sunny and exposed slopes.  But, you'll still be able to find soft powder-like snow conditions on sheltered slopes facing the northern half of the compass.  Many of the more popular areas are extensively tracked and could use a good refreshing.  Fresh snow should pile up pretty quickly Friday as the day progresses, which will improve the powder conditions while compromising visibility.  It'll be a good day not to forget the extra goggles.  With two waves of storminess on tap for this weekend, the avalanche danger will certainly be rising in the backcountry. 

Avalanche Conditions:

This week, many slopes in the region developed weak surface snow due to cold clear nights in the mountains. After being buried and preserved by snowfall, this fragile snow might end up being what we call a "persistent weak layer."  These can be especially dangerous because they lead to avalanche danger, which often lingers well beyond the normal period of instability after a storm.  As the next round of Pacific storms are on our doorstep we are cursed with a few different weak surface snow problems.  I've noticed lots of intact frost crystals or surface hoar recently, in some cases forming a congruous layer on the snow surface across entire slopes.  Another concern is newly formed, weak and sugary or faceted snow transformed by temperature gradient metamorphism near the snow surface.  In many cases this type of weak snow will form at the same time as, but just underneath the feathery frost crystals on the surface.  On sunny slopes, melt-freeze crusts of varying thicknesses and strengths formed, and in some cases weak faceted and/or frost crystals grew right on top of them.  I've also still been able to find clean mid-pack shears on some slopes, failing in the moderate range with compression tests.  With enough of a load (possibly this weekend?) I wouldn't be awfully surprised to hear of some avalanches stepping down into older snow.

With a healthy shot of snow in the forecast, the key wildcard for Friday will be the accompanying wind. If enough wind-deposited snow accumulates on steep slopes with existing weak surface snow, avalanches are likely to result.  On Friday you might be able to trigger new snow wind-slab avalanches on some steep slopes in the region.  The danger will rise throughout the day as heavy snowfall accumulates and is deposited into lee-slope avalanche paths.  Windier than forecast conditions will cause the danger to rise more rapidly since even more snow will be deposited.

Bottom Line:

 There is a MODERATE danger and new snow avalanches are possible on some wind-drifted slopes steeper than about 35 degrees in the backcountry.  With more snow and wind in the forecast, the avalanche danger is likely to rise farther this weekend.

General Information: 

 For a list of our upcoming classes and awareness talks, go to our Education page . For a list of recent avalanches in  the regional backcountry go to Avalanche List.  Snow nerds, check out the new Snow Profiles page.  You may enjoy our Images Page.

Please send backcountry observations to [email protected] or leave a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We really want to hear from you, even if you think your observation is unimportant.    The information you provide may save lives...

 This advisory will expire on Friday night.  I will update it again on Saturday morning by about 7:00.

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. 

National Weather Service - Salt Lake City - Snow.