Issued by Toby Weed on Wednesday morning, December 30, 2015
MODERATE (level 2): Heightened avalanche conditions exist in the backcountry, especially in drifted terrain at upper and mid elevations. Although conditions are becoming more stable, you still might trigger a dangerous deep slab avalanche in some areas, most likely from an area on a steep slope where the snow is shallow or rocky. Avalanches could be triggered remotely, from a distance or possibly from below. Evaluate the snow and terrain carefully and make conservative decisions.
The snow continues to stabilize in the backcountry, but you still might trigger dangerous avalanches in some areas. You'll find nice settled powder riding conditions across the zone, and thanks to Santa's storm, supportable snow now keeps you up off the rocks and deadfall in most areas.Cold temperatures and cloud cover are keeping the settled powder nice and soft on most slopes, even in the sun. The cold snow is sharp and a bit slow, but it's easy to break trail since you don't sink in very deeply. You can ride almost anywhere, but you should be cautious in avalanche terrain because you might trigger a very large and destructive avalanche, most likely from an area where the snow is thin.
The Tony Grove Snotel at 8400' reports an inch of new snow from overnight and 8 degrees. The station reports 18 inches of settlement in the last 6 days (since Christmas Eve), and there's now 52 inches of total snow, containing 102% of average water content for the date. It's 11 degrees at the 9700' CSI Logan Peak weather station, which is showing southwest winds averaging in the twenties this morning.
Recent Avalanches
Observers report fresh wind slab and cornice fall activity in upper elevation terrain in the Central Bear River Range, but the avalanches were fairly small. Evidence of natural activity from last week's productive storm is widespread across the Logan Zone. Most of the natural avalanches occurred early in the storm, but there are also a few that appear to be more recent. Of note, large natural avalanches occurred last week in fairly sheltered treed terrain in the Providence Canyon Area including an exceptionally large one in the popular Dog Leg Trees.
No avalanche incidents were reported locally since the weekend before Christmas.
On 12/19 an experience local rider was caught and carried through trees, mostly buried, and trapped by an avalanche he triggered above the Tony Grove Campground. Video Report
On 12/20 a skier remote triggered a large Deep Slab avalanche high on the south rim of lower Logan Canyon.
I observed several large more recent avalanches in the upper Providence Canyon area on Saturday. I think these were Christmas Eve naturals, but they might've been remote triggered, unseen by riders in limited visibility.
There was extensive natural avalanche activity in upper Providence Canyon, with large avalanches having occurred at different times during the pre-Christmas Storm. Most of the large paths in the area avalanched. Pictures above are of Three Terraces Bowl and the crown of a slide on the north side of Providence Peak. Both look to have gone big around Christmas Eve. I think the activity was natural, but being in such a popular riding area, some of the avalanches may have been remote triggered.(12-26-15)
***To view our updated list of backcountry observations and avalanche activity from around Utah, go to our observations page
Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Widespread very weak snow was overloaded by a few feet of heavier drifted snow last week creating an unstable situation, with a cohesive slab sitting on weak sugary or faceted snow. Settlement and cold temperatures have helped to stabilize the snow and in many areas the slab layer is so thick that it would be very difficult for riders to trigger, but heightened avalanche conditions persist in many areas and dangerous deep slab avalanches might be triggered from shallower areas on the slab today, especially in drifted terrain at upper and mid-elevations.
***Pay close attention to signs of unstable snow like recent avalanches, whumpfing, and shooting cracks, and be willing to reevaluate your plans. In these conditions you could still trigger avalanches remotely, from a distance or worse, from below!
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Winds from the west-northwest yesterday evening and overnight drifted snow in exposed terrain, and shallow fresh wind slabs again developed near ridge tops and in and around terrain features like gullies and rock outcroppings. A smaller wind slab avalanche overrunning a slope below, in some areas might trigger a larger and more destructive avalanche involving old weak snow.
Additional Information
STATE WEATHER SYNOPSIS...A SERIES OF WEAK DISTURBANCES WILL KEEP COLD AND UNSETTLED CONDITIONS OVER THE AREA INTO THURSDAY. A CONTINUATION OF COLD CONDITIONS ARE EXPECTED HEADING INTO THE WEEKEND. A SERIES OF WEAK SYSTEMS FROM THE SOUTHWEST HAS THE POTENTIAL TO BRING UNSETTLED CONDITIONS TO THE AREA EARLY NEXT WEEK.
General Announcements
The CROWBAR backcountry ski race will be Saturday January 30. More info at http://CrowbarSkiRace.org.
Please submit snow and avalancheobservations from your ventures in the backcountry HERE. You can call us at 801-524-5304 or emailHERE, or include #utavy in your Instagram or Tweet us @UAClogan. To report avalanche activity in the Logan Area or to contact the local avalanche forecaster call me, Toby, at 435-757-7578.
I'll update this advisory throughout the season on Monday, Wednesday, Friday, and Saturday mornings by about 7:30
This advisory is produced by the U.S.D.A. Forest Service, which is solely responsible for its content. It describes only general avalanche conditions and local variations always exist.
