There was a very close call Wednesday on the Raven Headwall. A solo skier, on the final leg of the Eklutna traverse, was caught, carried around 800′ and buried to their shoulders in a large avalanche. They were able to self rescue and are OK. The skier triggered the slab on the upper mid-slope while descending. The slab fractured around 30-50′ above the skier. This appears to be a large wind slab formed by the strong northerly outflow winds on Tuesday and Wednesday. The wind slab may have been sitting on weak snow, allowing it to propagate across the entire headwall. We would like to thank the skier for telling their story and please take a moment to read their account HERE.
Large skier triggered slab on the Raven Headwall. 3.11.20. Photo: Anonymous
Close up of the crown face. This appears to be a wind slab that formed from the strong outflow winds Tuesday and Wednesday. 3.11.20. Photo: Anonymous
|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
And…. it’s springtime. Light winds, warm temperatures and long sunny days are here. Starting today, we are on a warming trend that should last through the weekend and even into Monday. Not only does this weather invite trips into the far reaches of the mountains, it also invites a new factor for avalanches; sunshine and warming. We can’t let the hospitable weather lower our guard.
As we’ve been mentioning, there is a thin layer of buried surface hoar around 1-2 feet below the surface in many areas. Even deeper in places that saw significant wind loading mid-week by the northwest outflow winds, such as the Raven Headwall avalanche mentioned above. This layer has not been found everywhere, but has been prevalent enough that it’s keeping us concerned. It also may be sitting on a sun crust on steep southerly slopes, making it that much more reactive. That said, triggering a slab large enough to ruin our day is still very much possible. Keep a close eye out for stiff snow over softer snow and cracking in the snow around you. Watch for slopes with wind loading as these are the most suspect places to trigger a slab.
Sun Effect: With light winds, direct sunshine and warm air moving in aloft we can expect solar aspects to warm dramatically over the next couple days. This change is a shock to our snowpack. It not only moistens the surface, creating easily triggered moist sluffs (and natural ones as well), but it can increase the likelihood of triggering a slab avalanche. It can also help to re-active older weak layers that sit very deep in the snowpack. In our case the January facets that are 3-6 feet deep. Will the sunshine this weekend be enough to do this? Probably not, but something to keep in mind as we move forward.
Cornices: Avoid travel on cornices and move quickly underneath them. Remember, warming temperatures and direct sun are classic mechanisms for destabilizing these monsters.
Large cornice that sits on the north side of Superbowl (head of Cornbiscuit and Magnum). 3.12.20. Photo: Heather Johnson
Dry loose snow avalanches: In shaded areas that were protected from the wind, sluffs are possible in steep terrain.
Yesterday: Sunny skies and warming temperatures were over the region yesterday. Lower elevations rose from the single digits to the mid 20’s°F and upper elevations rose to the mid-teens. Ridgetop winds were light with a few moderate gusts from the NW.
Today: Another sunny day is on tap with a stout inversion in place this morning. High pressure is building over Southcentral and bringing in warm air aloft, which is warming the higher terrain (Sunburst is reporting 17°F at 5am) but valley bottoms remain in the single digits. Daytime highs should reach into 20’s°F at all elevations today. Ridgetop winds are expected to be light and westerly.
Tomorrow: Sunny skies, light winds and warming temperatures are forecast for the weekend. Springtime weather is here. Ridgetops could see temps hit 30°F Saturday and even higher on Sunday. Winds are slated to remain light and variable.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||13||0||0||68|
|Summit Lake (1400′)||10||0||0||31|
|Alyeska Mid (1700′)||13||0||0||80|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||12||N||3||7|
|11/30/22||Turnagain||Observation: Tincan||John Sykes Forecaster|
|11/28/22||Turnagain||Observation: Pastoral||Schauer/ Wadsworth Forecaster|
|11/26/22||Turnagain||Observation: Eddies||Schauer/ Cullen Forecaster|
|11/26/22||Turnagain||Observation: Eddies||Andy Moderow|
|11/26/22||Turnagain||Observation: Lipps||Big Ripper|
|11/25/22||Turnagain||Observation: Sunburst||Hannah Smith|
|11/25/22||Turnagain||Observation: Sunnyside / Seattle Ridge||Matti Silta|
|11/25/22||Turnagain||Observation: Sunburst||John Sykes Forecaster|
|11/25/22||Turnagain||Observation: Tincan Trees||Andy Moderow|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.