|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|
Today is an avalanche problem transition day. Since March 2nd wind slab has been Problem #1. We have had a series of northwest outflow events and with a swing or two back to elevated southeast winds. Today the winds are forecast to ease off and become calm. Could you find a lingering wind slab that just involves layers of wind deposited snow not bonding in wind loaded terrain? Yes. However, the main concern is triggering an avalanche that fails on buried surface hoar which is considered a persistent weak layer. This layer was buried around Leap Day and has been found in snow pits around much of the forecast area. It is generally around 1-2′ below the surface. The surface hoar is the suspected weak layer in the Lynx avalanche last Thursday, and some small skier triggered avalanches around Girdwood and potentially the avalanche triggered in Palmer creek yesterday. It is most likely going to be an issue where it is buried under wind affected snow forming a slab. Hence the transition from a wind slab to persistent slab. Additionally, the surface hoar layer may also be reactive as warm temperatures and sunshine change the character of the soft snow into a slab in more protected areas.
A challenge with a surface hoar layer is that it may not be widespread across terrain and may or may not be an issue depending on what the snow below the layer of surface hoar is like. Surface hoar that formed on hard snow or a crust is more of a concern. You could happen to hit a zone with the lurking layer and trigger an avalanche or not! What does all this mean today? Pay attention to terrain features that look loaded or pillowed, watch for cracking or collapsing, and terrain with hard snow over a softer layer. Use small test slopes and hand pits to see if the snowpack is reactive. Don’t forget this type of avalanche may be triggered remotely.
Cornices: Avoid travel on cornices and limit exposure underneath them.
Loose snow avalanches: In areas that were protected from the wind, sluffs are possible in steep terrain.
Sun effect: The sun is starting to have an impact on surface snow on steep solar aspects. Be aware of moist surface snow, small roller balls or loose snow avalanches in wind protected spots, especially below steeper rocky areas. As temperatures warm this weekend, it may also make triggering an avalanche on buried weak layers more of an issue.
Yesterday: Skies were clear and temperatures were in the single digits and low teens at upper elevations and in the teens to upper 20°Fs at low elevations. Winds were westerly 5-15 mph with gusts into the 20s. Winds recorded at the AKRR MP 43 station were 10-25 mph with gusts into the 40s. Overnight skies remained clear and temperatures ranged from the low teens above 0°F to low teens below 0°F. Westerly winds continued to be gusty through the night.
Today: Skies will be clear with temperatures in the low teens to high 20°Fs. Winds will remain westerly and ease off becoming light by the afternoon. Overnight temperatures will be in the single digits and low teens with calm winds.
Tomorrow: Another day of sunshine is on tap with temperatures climbing into the high 20°Fs to low 30°Fs. Winds will be light and westerly. The clear sunny trend continues over the weekend with mostly calm winds and increasing temperatures.
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′)||7||0||0||31|
|Alyeska Mid (1700′)||10||0||0||80|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||9||W||3||14|
|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: 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.