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Logan area Avalanche Advisory

 

7:30, Wednesday March 26, 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 Wednesday March 26th, 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 AvalancheTools.com.  

Current Conditions:

Several inches of new snow fell yesterday in the Central Bear River Range, but strong west winds wrecked havoc at upper elevations, building stiff drifts and scouring snow from windward slopes and dumping it into lee-slope fetch areas.  The Tony Grove Snotel reports 8/10ths of an inch of water in the last 24 hrs, and there’s almost 8” of new snow showing up on the remote snow stake at Beaver Mountain…Temperatures hovered just above freezing for most of the night at the 8400’ Tony Grove Snotel, and any superficial surface crusts at low and mid elevations will quickly soften as warm spring-like conditions persist through this morning. West winds picked up steam yesterday and they’ve been steady and fairly strong overnight, with the CSI weather station on Logan Peak reporting sustained hourly averages in the upper twenties with gusts in the mid-forty mph range. 

  Avalanche Conditions: 

Wet activity grabbed the headlines yesterday afternoon across the mountains of Northern Utah, with slopes covered by previously dry snow at all elevations warming and becoming active.  There were several large wet avalanches on shady lower elevation slopes locally, the most noticeable in Logan Canyon.  I noticed where one above the river near Temple Fork stepped down to the ground 3 or 4’ into old deposition.  Fresh wind slabs formed yesterday at upper elevations and we found a number of sensitive shallow pockets above 8500’.   I’m still concerned by the possibility of isolated persistent slab activity and I repeatedly found a clean and energetic shear failure in test pits on a layer consisting of graupel and small faceted grains one to two feet below the snow surface.  This is the same layer that failed on the East Face of Naomi Peak over the weekend, (photos).

Wind slab avalanches are most likely on steep upper elevation slopes with significant deposits of recently drifted snow.   Isolated persistent slabs are still possible on very steep slopes above 8000’ in elevation and facing the northern half of the compass.  Many avalanche slide paths in the area are well filled-in and smooth, so even relatively small wind slab avalanches might run far or fast.

Especially if the sun peaks out, significant wet avalanches are possible on steep slopes again today as warmth turns the already saturated snow into slush.   You might find even smallish wet avalanches entraining lots of mass and traveling far.  Cooling and cloud cover this afternoon should help to solidify things down low, but it’ll be a good idea today to avoid and stay out from under steep slopes with melt-saturated snow at all elevations.

Bottom Line: 

  Overall there’s a MODERATE avalanche danger in the backcountry, and you could trigger avalanches on drifted or saturated slopes steeper than about 35 degrees.  Pockets with a CONSIDERABLE danger exist at upper elevations on steep slopes with significant deposits of wind drifted snow in the Central Bear River Range and the mountains near the Idaho State Line.  Wet avalanches will become possible at all elevations in the midday heat as the snow on any steep slope is warmed and becomes saturated. 

Mountain Weather: This morning’s wave of moist weather should be on the way out and we’ll probably see some clearing ahead of the next bout, which will affect the region tonight and tomorrow.  Southwest winds should be fairly strong throughout the day today, and a cold front will sag southward across the area later this afternoon bringing snowfall.  We could see several inches of accumulation before things wind down tomorrow afternoon. Similar moist and windy weather is on the way for the weekend.

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.