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 March 30, 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 March 30th at 9:30 pm.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Avalanchetools.com.

Current Conditions:

You can find decent powder conditions, especially at higher elevations and on northerly facing slopes. This week's storm was more productive for the Wasatch Range than for the Bear River Mountains. In the past 72 hours, the Ben Lomond Snotel, with 3.2 inches recorded more than triple the water equivalent accumulation of Tony Grove, which only recorded 1 inch. Trail-breaking isn't bad since you don't sink too deeply into this week's new snow.  I found myself staying for the most part on top of yesterday's refrozen heavy snow, riding in a few inches of colder, fresh powder from overnight.  I only got the sled stuck once, when I lost momentum on a hill and spun my track through a weak warmth crust formed yesterday.

Snow and Avalanche Conditions:

 A south wind will be on the increase during the day Friday, and freshly built and forming wind-drifts will once again be our biggest avalanche concern.  Ridge-top winds should be strong, averaging around 30 mph, and there are several inches of light, transportable snow on the surface.  Sensitive wind-slabs will quickly form on lee slopes and around terrain features like gullies, rock outcroppings, and sub-ridges.  You should avoid stiff, rounded deposits on steep slopes.  Watch and listen for signs of instability like shooting cracks and hollow sounding snow.  Think about potential terrain traps below you like trees or cliffs, which may make even smaller avalanches dangerous.

Rain and warm temperatures caused widespread natural wet loose snow avalanching on steep mid and lower elevation slopes in the Bear River Range on Wednesday.  Most of the avalanches were pretty small, but they left some pretty big piles of deposition below steep slopes and cliff areas.  I noticed a few sizable natural avalanches above the town of Mendon in the Wellsville Range, which ran around 2000 vertical feet from ridge-top cornice-line starting zones to the gully terminuses on Maple Bench.  These may have started as cornice falls or dry wind-drift avalanches, but as they descended in altitude they probably began gouging down, pushing trains of wet snow down the long and sustained run out gullies.

The south winds will bring warm air into the region, and the sun could peak through building high clouds.  Long wave solar radiation may be trapped in the atmosphere and green-housing could be a factor.  Wet avalanches will become more likely in the warmest part of the day as the fresh snow on steep slopes warms up and gets saturated and sloppy.  If you start noticing lots of snow snails or roller-balls, the snow is almost ready to sluff out on steep slopes.  Recent point-release avalanches on similar slopes are a sure sign.

Bottom Line:

There's a MODERATE danger and avalanches are possible on some slopes steeper than about 35 degrees in the backcountry.  You could trigger wind slab avalanches on upper and mid-elevation slopes exposed to drifting from strong south winds, and as the winds continue throughout the day, the problem will become more widespread and potential avalanches deeper.  Seasonal warming and green-housing may cause a daytime danger of wet avalanches on steep sheltered slopes at lower and mid-elevations.

Mountain Weather:

Tomorrow's strong south winds herald the next storm for the weekend. This one scheduled for Saturday day will be a quick-hitter, with 6 inches to a foot possible at upper elevations. We'll get a short break on Sunday.  A larger, potentially very productive storm will begin to affect the region on Monday, and the long-lasting storm could drench the area through much of next week.  Stormy weather extends as far out on the radar screen as we can see at this point.  There's still no end to winter in sight.

General Information: 

If you're confused by some of our avalanche terms check out the cool new Avalanche Encyclopedia. 

For a list of recent avalanches in  the regional backcountry go to Avalanche List.  Snow nerds, check out the new Snow Profiles page.  Check out our Images Page for pictures of recent local avalanches.

Please send backcountry observations to uaclogan@avalanche.org 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, but I will update it again on Saturday morning by about 7:00 am.

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.