There were several recent avalanches reported yesterday that were all on the small side (D1). Two avalanches were triggered in the Tincan Common area on south facing slopes where the new snow was not bonding well to the old icy snow surface. Similarly on Sunburst there was another southern aspect with a small surface snow avalanche. In areas that received consistent sunshine yesterday dry loose avalanches triggered by the sun on southern aspects were also observed.
|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|
Heavy snowfall and strong winds will start again today which will rapidly increase avalanche danger. We are expecting 10-12″ of new snow during the day with periods of very heavy snowfall. The highest snowfall totals are expected to be near Girdwood and areas closer to Prince William Sound, like Portage. Wind speeds should be in the 40-60 mph range at upper elevations with stronger gusts. This rapid loading of the snowpack, which is still adjusting to the last foot or more of new snow that fell in many areas on Wednesday, will likely be enough to cause widespread natural avalanches 1-3′ deep in areas with active wind loading. In areas sheltered from the wind natural and human triggered avalanches avalanches 1-2′ deep are likely because the last round of snow did not bond very well to the old snow surface.
After the last round of snowfall we saw avalanche activity on southern aspects that had a sun crust on the old snow surface. With more stress added to the snowpack today it is possible that we could also start to see larger and more connected avalanches releasing on shaded slopes that have a buried weak layer of facets underneath the last round of snow. In general today is a good day to step back from avalanche terrain and give the mountains some space to adjust to the incoming storm. We recommend avoiding avalanche terrain, especially in areas with active wind loading, and being very aware of any avalanche paths overhead that could release naturally.
In areas of the forecast region with a thinner overall snowpack, like near Johnson Pass, there is the potential for avalanches on deeper buried weak layers that we are still concerned with. The rapid loading today with new snow and wind could be enough to reactivate these buried weak layers and larger avalanches with wide propagation are possible. We recommend an extra conservative mindset in these areas because there is the potential for a large avalanche to release at upper elevations and run into lower elevations.
Yesterday: Mix of cloudy conditions and periods of broken skies with sun poking through. Turnagain Pass and the Portage/Placer area picked up another 0.2-0.3″ of water which should be roughly 2-3″ of snow. Winds were moderate to light at lower elevations and stronger at upper elevations. Sunburst had average wind speeds of 10-15 mph and gusts of 15-30 mph with occasional stronger gusts up to 50 mph. Temperatures remained in the teens to mid 20s F with snow falling down to sea level.
Today: Heavy snowfall and strong winds are expected to pick up again this morning. 10-12″ of new snowfall is forecast during the day today in Turnagain Pass and Girdwood with higher totals expected in areas closer to Prince William Sound. Over the next 24 hours Turnagain Pass could receive up to 12-18″ of new snow, with Girdwood estimated at 18-24″, and Portage possibly closer to 18-30″. Accompanying all the new snow will we wind speed averaging 40-60 mph at upper elevations with stronger gusts. Snow line could creep up to about 500′ today with some warmer temperatures accompanying this low pressure system.
Tomorrow: Light snowfall is expected to continue during the day tomorrow with mostly cloudy skies. An additional 2-3″ of snowfall is possible during the day and then another strong pulse of snowfall is expected to start late Saturday into Sunday. This second strong pulse of moisture could bring up to another 6-10″ of snow by Sunday morning. Even stronger winds will accompany the second pulse of moisture with wind speeds reaching 80 mph at upper elevations on Saturday evening through Sunday morning. Storm totals from Friday morning through Sunday morning could be as high as 20-25″ for Turnagain Pass and Girdwood, and closer to 30-36″ in Portage. These might be optimistic values, but the weather models seems to all agree that at least some heavy snowfall will impact the area this weekend.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||25||2||0.2||76|
|Summit Lake (1400′)||24||1||0.1||40|
|Alyeska Mid (1700′)||24||0||0||66|
|Bear Valley – Portage (132′)||27||2||0.23||–|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||18||SE||4||12|
|05/22/23||Turnagain||Avalanche: Tincan||Nick D'Alessio|
|05/12/23||Turnagain||Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit||Heather Thamm|
|05/07/23||Turnagain||Observation: Tincan – Bear Tracks||CNFAIC Staff|
|05/05/23||Turnagain||Observation: Seattle Ridge||AS/ WW Forecaster|
|05/02/23||Turnagain||Observation: Cornbiscuit||Schauer/ Sturgess Forecaster|
|05/02/23||Turnagain||Observation: Seward Hwy Turnagain Pass||Joel Curtis|
|04/30/23||Turnagain||Observation: Magnum||Ayla, Kit Crosby, Barton|
|04/29/23||Turnagain||Observation: Tincan||John Sykes|
|04/28/23||Turnagain||Avalanche: Taylor Pass/Pastoral||Schauer/ Creighton Forecaster|
|04/28/23||Turnagain||Avalanche: Tincan||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.