Glide avalanches are unlike any other avalanche problem and don’t fit well in the North American Danger Scale. They release without warning and are not associated with human triggers. They are a high-risk low likelihood avalanche problem, and the only way to mange this problem is by avoiding terrain with glide cracks.
SO WHAT DOES THIS ALL MEAN?
We as avalanche forecasters have NO IDEA which glide cracks are going to release on any given day. What we do know is the frequency of glide avalanches is on the rise. Since Friday (4/1) five large glide avalanches occurred on Seattle Ridge, including one mid-day yesterday. Another handful of glide avalanches were also observed yesterday between Girdwood and Turnagain Pass.
The reason this is so alarming is that new glide cracks are appearing daily and many threaten popular terrain. The Seattle Ridge uptrack is one of our biggest concerns because a large crack now puts this popular route in the line of fire. If you were to be in the wrong place at the wrong time you would not survive a glide avalanche. High marking or setting a skin track under a glide crack is not recommended EVER!
Recent high marking was observed yesterday below a large glide crack on Seattle Ridge. Notice how portions of the uptrack are also within the runout of this fast growing glide.
We were impressed by the frequency and size of the glide activity on Seattle Ridge yesterday compared to the day before.
A glide avalanche occured mid day yesterday on Seattle Ridge accross from the Sunburst parking lot.
As we work our way through this springtime regime and transition from a winter snowpack to a summer one, it’s time to think about how the surface is warming/softening, or not warming/softening. This is not only for sussing out good ski/riding conditions but for wet avalanche hazards as well. Yesterday we saw unsupportable and wet snow below 2,500′ where it was easy to initiate wet sluffs in steep terrain. Has this wet snow frozen overnight? Most likely there has been a shallow re-freeze limiting any wet avalanche hazard. However, temperatures climbing today and the likelihood of sunshine may soften surface crusts again, allowing for wet avalanche activity to increase throughout the day. Mid elevations below 2500’ will be the most suspect, but you should still pay attention to solar aspects in the Alpine.
Wet snow rule of thumb: If the snow is wet and mushy enough for your boot to sink in up to your ankle, or more, wet sluffs are possible and it’s time to find a more supportable slope. Also, wet sluffs can be quite dangerous as the debris is heavy, can generate a lot of momentum and be extremely difficult to escape.
This a great way to test the strength of the snow. If the snow is unsupportable and you are punching through avoid steep terrain.
We have yet to start seeing cornices begin to fall in earnest, yet it is still wise to give these very large snow features a wide berth along ridgelines and limit your time below them. Cornices typically calve off around now as we move into a springtime snowpack.
Yesterday skies were mostly cloudy and scattered showers left a trace of new snow in the Alpine. Daytime temps reached a high of 42F at Center Ridge SNOTEL and overnight temps reached a low of 28F. In the alpine temperature remained cooler, mid to high 20F’s and ridgetop winds were Light to Moderate from the East.
Today will be mostly sunny and temperatures will likely reach the mid 40F’s at 1000′. In the alpine temperatures are expected to reach the mid 30F’s and Ridgetop winds be light, 5-10mph, from the East. Overnight temps are expected to drop into the 20F’s.
Tomorrow looks like more cloud cover with a chance of scattered rain/snow showers and patches of sun. Similar temps and winds are expected tomorrow.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||35||trace||0.1||118|
|Summit Lake (1400′)||35||0||0||37|
|Alyeska Mid (1700′)||35||trace||0.01||105|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||27||SE||14||31|
|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.