Our main avalanche concern today is one that will not go away quickly. Surface hoar that formed a week ago has been preserved and is sitting below 1-3’ slabs. Typically surface hoar gets knocked over and blown around before a slab builds on top of it. That is not the case with our current snowpack. The snowfall that began on December 13th came in with very little wind and allowed this layer to be buried intact. We have been investigating this layer over the last several days and we have found it in all pits above 2,700’.
The tricky part with this set up now is that it is gradually becoming more difficult to trigger an avalanche. We know this based on our test results in snow pits. Unfortunately, it will be possible to test this layer by traveling in steeper terrain and not get results (NOT RECOMMENDED!) Exceptions to this were found on Sunburst and in the Summit Lake region, where skiers remotely triggered an avalanche from 50’ away. In areas such as this where the snowpack is thinner, it will be easier to initiate an avalanche today.
The nature of buried surface hoar is such that it persists as a weak layer in the snowpack for many days, sometimes weeks after it becomes buried. Because of this we will be tip toeing around the mountains for the foreseeable future.
In order to stay out of trouble it is best to avoid steep terrain. Terrain on all aspects over 35 degrees should be treated as suspect. Avalanches, if initiated have the very real potential of propagating across large areas, making escape difficult at best. There is plenty of evidence to support this and the problem will potentially take a long time to go away.
Below 2,500’ in elevation the likelihood of triggering a slab avalanche 1-2’ in depth will be less than in the higher elevations. A crust that has formed in the middle of this newest slab will make it harder to trigger any buried surface hoar that survived the rain and wet snow. We cannot rule out the potential for triggering slabs in this elevation band and it will be important to keep slope angles low until we see more signs of this layer becoming non-reactive.
Paying attention to what is above you, including other groups, when in this elevation band (bewteen 1,500-2,500′) will be important as avalanches initiated in the higher elevations could run into the mid elevations today.
In the past 24 hours the precipitation has shut off and the temperatures have cooled – see table below. Winds have picked up slightly overnight along ridge tops and are averaging in the 20mph range out of the East at Sunburst this morning.
Today expect light snow showers with 2 € accumulation possible. Temperatures at 1,000′ will be in the high 20s to low 30s F range. Winds will be out of the Northeast at 10-20 mph.
The extended outlook is showing some potential for more precipitation as a complex series of Lows move through the Gulf and along the Aleutian chain over the next several days. There is a high level of uncertainty as to the timing and track of these systems with the next best chance for snow coming Sunday into the early part of next week.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||28||0||0||28|
|Summit Lake (1400′)||24||0||0||4|
|Alyeska Mid (1700′)||27||0||0||18.5|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||22||N/A||N/A||N/A|
|04/21/21||Turnagain||Observation: Sunburst||Schauer/ Behney Forecaster|
|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|
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.