|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|
Am I traveling in terrain that is harboring a slab over a buried weak layer? This is the question of the day. With the few inches of low density snow that fell overnight it will be harder to see evidence of prior wind-loading. While typical wind slabs generally heal soon after a wind event. When the slabs form over a persistent weak layer, like surface hoar or facets, they can become a persistent slab issue. This is unfortunately what we are dealing with now. A weak layer of surface hoar and near surface facets was buried last week by 4-18″ of snow. The most snow (12-18″) fell in Placer, Portage and Whittier with much smaller amounts (4-6″) at the southern end of Turnagain Pass and to the north in Crow Creek. Girdwood and the northern end of the pass got 8-12″. The snow was followed by light to moderate winds which formed wind slabs in some terrain and there were a number of human triggered avalanches reported over the weekend. While the weak layer may be found on most slopes in the area, the wind effect was variable. The key factor to determining stability today will be whether the wind formed a slab of stiffer snow above the weak layer or not and how deep is the slab. Ski and track penetration and snow stiffness will help answer these questions. Is the snow loose and sugary or stiff and maybe supportable? The most suspect areas are loaded slopes at higher elevations. Remember there was loading from a variety of directions as winds shifted from east to west. Avoid steep terrain with stiffer snow and look for signs of instability like cracking, whumpfing. On the flip side, keep in mind that signs of instability may not be present as time passes with a persistent weak layer in the snowpack. However, the potential to trigger an avalanche will still be there. There is lots of fun, soft snow to enjoy in non wind affected terrain.
Loose snow avalanches (sluffs): Sluffs are likely to be high volume and fast running. They could entrain the new snow as well as the facets that sit below it and could have serious consequences if they carry you into terrain traps like cliffs, trees, or rocks.
Cornices: Large cornices are peeling away from ridgelines and cracks are opening. Be sure to give them plenty of space along the ridge and minimize the amount of time you spend below them.
Glide cracks exist across the forecast area. Remember it is important to limit time spent underneath them. Glide avalanches are totally unpredictable, not triggered by people and are the entire snowpack sliding at the ground. This type of avalanche could be large and unsurvivable if you happened to be in wrong place when one releases. If you see recent glide activity please let us know.
Yesterday: Skies were overcast and temperatures climbed from the single digits to the mid teens as the day progressed. Winds were calm becoming easterly and light overnight. Light snow showers started in the early evening and continued overnight with 1-2″ of accumulation to sea level.
Today: Skies will be mostly cloudy in the morning becoming partly sunny in the afternoon with some valley fog possible. Temperatures will be in the high teens to mid 20°Fs and winds will be light and westerly. Overnight skies will be partly cloudy with temperatures in the teens to single digits and light west winds continue.
Tomorrow: Mostly sunny skies with temperatures in the teens and mid 20°Fs and light NW winds. The next shot of snow looks to be Friday into Friday night.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||14||1||0.1||123|
|Summit Lake (1400′)||11||2||0.2||44|
|Alyeska Mid (1700′)||14||2||0.15||111|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||11||SE||4||12|
|05/18/21||Turnagain||Observation: Tincan Ridge||Joe Kurtak|
|04/30/21||Turnagain||Observation: Sunburst||W Wagner Forecaster|
|04/27/21||Turnagain||Observation: Tincan Ridge||Joe Kurtak|
|04/26/21||Turnagain||Observation: Magnum||Creighton/ Hoople|
|04/25/21||Turnagain||Observation: Sunburst||Nick D'Alessio|
|04/24/21||Turnagain||Observation: Airplane obs||Johnston-Bloom / DiJulia /Hilliard Forecaster|
|04/24/21||Turnagain||Observation: Corn biscuit||Heather Johnson|
|04/23/21||Turnagain||Avalanche: Lynx Ck Drainage||W Wagner Forecaster|
|04/23/21||Turnagain||Avalanche: Sunburst||Eeva Latosuo|
|04/23/21||Turnagain||Observation: Center Ridge Turnagain pass||Joe Kurtak|
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.