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Logan area Avalanche Advisory


7:30, Friday March 21, 2008

Hello and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  It’s Friday March 21st, at 7:30 in the morning.  Today’s advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Black Diamond.  

Current Conditions:  The Bear River Mountains picked up a good shot of somewhat heavy snow yesterday, with the Tony Grove Snotel reporting 1.4 inches of water equivalent from the storm.  With a bit more than a foot of new snow in upper elevation terrain, you should be able to find some fairly good riding conditions today.  Solar warming got to the already saturated new snow at lower elevations, and I expect you’ll find typical springtime morning crusts and midday slush on sunny slopes at all elevations.  Clouds and snow showers will diminish this morning and we’ll see partly cloudy skies and a fair amount of sunshine in the mountains today.  The Campbell Scientific weather station on Logan Peak recorded west and northwest winds averaging in the upper teens overnight, and it’s 17 degrees at 9400’.  It’s a much warmer 36 degrees in Logan Town.

  Avalanche Conditions: 

We noticed a handful of fresh natural wind slab avalanches at upper elevations on Wednesday after moderately strong westerly winds overnight on Tuesday.  After an exceptionally warm day on Wednesday, large natural wet point-release type avalanches occurred in Logan Canyon in the evening.  Tons of snow was dumped into the Logan River near Temple Fork with several wet slides gouging all the snow out to the ground.  One such wet slide hit hwy 89 in the Dugway, burying the eastbound lane, (photos from 3-19).   Rain and warmth at lower elevations yesterday only exacerbated the wet avalanche problem, and saturated new snow flowed off sunny low and mid elevation slopes like melting wax off a candle, (photos).  Significant natural wet avalanches were widespread, and we were easily able to trigger long-running wet sluffs in the Wellsville Canyon area yesterday.

Triggered soft slab or storm snow avalanches 1-2’ deep are possible on steep upper elevation slopes with significant deposits of new or recently drifted snow.  Sensitive drifts and wind slabs from Wednesday are now buried and obscured by up to a foot of somewhat heavy new snow.  Tests showed easy shears in the top few inches of snow at upper elevations in the Central Bear River Range before yesterday’s productive storm.    I noticed easy failures on small sugary grains called near surface facets yesterday, and I fear that we are plagued by this and other now buried persistent weak layers.  Many avalanche slide paths in the area are well filled-in and smooth, so even relatively small avalanches might run far or fast.

 Significant wet avalanches are likely on steep sunny slopes again today as solar warming turns the fresh surface snow into slush.   If yesterday’s activity was any indication, you’ll find even smallish wet avalanches entraining lots of mass and traveling far.  Continue to avoid and stay out from under steep sunny slopes with saturated snow at all elevations.

Bottom Line: 

  Overall, there’s a MODERATE avalanche danger in the backcountry, and you could trigger avalanches on many slopes steeper than about 35 degrees.  Pockets with a CONSIDERABLE danger exist in exposed upper elevation terrain and triggered avalanches are probable on some steep slopes with significant deposits of new or drifted snow.  Wet avalanches will become likely as the fresh snow is warmed on sunny slopes especially at lower and mid elevations, and you should avoid and stay out from under steep slopes with saturated snow.

Mountain Weather: A weak disturbance will graze Northern Utah this morning, bringing clouds and a little snowfall.  A high pressure system will bring fair weather and warming temperatures to the mountains for the weekend.  A series of weak storms will affect the region next week.

General Announcements: 

Check out the images page for photos of some of this season’s avalanches.

Go to the Avalanche Encyclopedia if you have any questions about terms I use in the advisory.

I'm very interested to know what you're seeing out there.  Please e-mail observations to me at [email protected] or leave me a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We keep all observations confidential.

This advisory will expire in 24 hours from the posting time.

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.