Today very warm daytime temperatures will be contributing stress to an already stressed weak layer that is sitting below a 2-3’ slab on Northern and Western aspects.
Over the last three days several skier triggered slab avalanches have confirmed this problem being widespread throughout Turnagain Pass on shaded slopes above 2500’. Yesterday we investigated a large skier triggered slab avalanche on a Northern aspect of Magnum that happened on April 1st. The slab depth was 2-3’ deep and it ran a total distance of 1300’ to the valley floor. The skier went for a 1000’ ride, but was not buried or injured. We could not access the crown, but dug a pit on a similar aspect and elevation and found several layers of weak faceted snow and crusts beneath a 2.5’ slab.
Obvious signs of instability like collapsing may not be present in the heart of our forecast zone (Tincan, Sunburst, Magnum) and assessing the snowpack on Northern slopes will be difficult to do safely. If an avalanche is triggered today the consequences will likely be high. It will be important to avoid steep Northern and Western aspects above 2500’ until the weak layer(s) have more time to adjust to the load.
Yesterday a group of skiers on Seattle Ridge felt a collapse and found a large avalanche in Main Bowl in a similar area they had just skinned through. (photo below) It is possible that they triggered it remotely from the Ridge, but it was unwitnessed. It occured between Noon and 1pm as temperature were suddenly rising. This event points to greater instability in this portion of the forecast zone. Photo by John Fitzgerald.
Over the last three days daytime temperatures have been rapidly increasing around 12pm and today’s hot sunny weather will likely see a similar spike. Springtime conditions exist on predominantly sunny slopes where the snow pack is likely to become saturated throughout the day on Southern and Eastern aspects. If daytime temperature climb into the mid 40’s to 50’s F as forecasted, wet loose and wet slab avalanches will be a concern at all elevations holding snow.
Cornices have grown very large over the last few weeks and with todays warm temperatures natural cornice fall is possible. If traveling along a ridge give cornices a lot of space– they can break farther back than you think. Adjust your route if you find yourself traveling below a cornice. In the right place (like Seattle Ridge area) a cornice fall could trigger a large slab avalanche.
Yesterday skies were overcast and in the afternoon and became partly cloudy. Temperatures were very warm, 30-40’s F at mid elevations. Along ridgetops temperatures reached the low 30’s F and winds were light from the Northeast.
Overnight temperatures dipped below freezing along ridgetops, but at mid elevations stayed in the low 30’s F. Ridgetop winds shifted from the Northeast to the West, but remained light (5-10mph.) An inch of new snow was recorded at Center Ridge Weather Station.
Today very warm and sunny weather is expected. Daytime temperatures will be warm, 30F – 40F. Near sea level temperature could reach the 50’s F during the warmest part of the day. Winds are expected to be 5-15mph from the North along ridgetops and no precipitation is expected.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||36||1||.01||60|
|Summit Lake (1400′)||35||0||0||10|
|Alyeska Mid (1700′)||35||0||0||33|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||30||Var.||3||11|
|04/19/21||Turnagain||Avalanche: Triangle, Seattle creek||Will Morrison|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/18/21||Turnagain||Observation: Seattle Ridge, approximately 300 yards south of the up track||Brent Byrne|
|04/17/21||Turnagain||Avalanche: Road obs||Johnston-Bloom / Moderow Forecaster|
|04/16/21||Turnagain||Avalanche: Seattle Ridge||Wendy Wagner Forecaster|
|04/16/21||Turnagain||Avalanche: Turnagain Pass, non-motorized side seen from Seattle Ridge||CNFAIC Staff Forecaster|
|04/16/21||Turnagain||Observation: Sunburst||Lance breeding|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer Forecaster|
|04/12/21||Turnagain||Observation: Tincan||Johnston-Bloom / Latosuo Forecaster|
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: email@example.com
|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.