We really need a spring avalanche icon for today to speak to the transitional nature of what is going on. The snowpack is not yet completely in a wet regime but it is on its way. This is most pronounced in the Alpine, where there is still cold dry snow that is being affected by warm temperatures. A number of factors are contributing to the potential for wet(ish) avalanches today. Yesterday was one of the warmest days we have had this spring and there was not a freeze overnight in the mid-elevation band. The surface of the snow was wet over 3000′. Additional rain fell onto storm snow last night, temperatures are forecasted to stay warm today and there is the possibility of afternoon sun. Yesterday it was easy to initiate damp-wet loose avalanches on steep slopes around 2000′ and large skier triggered roller balls were observed at 3200′ as the snow became damp. The snow from Monday’s storm all rests on a crust that is acting as a bed surface for avalanche activity. Hand pits yesterday showed colder snow just above the crust that was creating easy shears. Warmer, damp to wet, snow sits on top of this depending on elevation. This may also make isolated wind slabs easier to trigger (more on this below).
Today’s weather forecast is for rain showers that will add moisture to the snowpack and may cause natural wet loose avalanches in the mid elevation band. In addition, if the sun pokes out at all, it could also be a trigger for natural activity.
Today a skier or snowmachiner triggering a loose avalanche will be likely on slopes steeper than 35 degrees. Wet loose snow avalanches once initiated can entrain more snow rapidly and are very hard to get out of. They can be particularly hazardous if they push you into a terrain trap and bury you deeply. If your skis or snowmachine are sinking into wet snow this is an obvious clue that the snow is unstable.
Push-a-lanche potential at 2000′ on Tincan yesterday. These were gaining momentum and could easily push you into a tree well or tip you over.
Wet/storm slab that occured during Monday’s storm on Seattle Ridge with glide avalanche debris from yesterday on top.
The glide avalanches keep happening. As a snow geek, I was thrilled to watch one in action from the truck yesterday by Bertha Creek Campground but I was alarmed to see the recent large glide avalanches around the up-track on Seattle Ridge. The glide avalanche in this location also happened in conjuntion with a storm slab. The debris pile is quite large and runs over well-traveled terrain. There is plenty of glide crack potential still looming in this area. The glide cracks are moving, growing and new ones are appearing. We have been saying for months but the message is important, avoid travel underneath glide cracks.
Glide avalanches on Seattle Ridge including one near the up-track. Note the slab avalanche that also ran and where the debris from both piled up.
Glide avalanche above Bertha Creek Campgound. We watched this run at 11:30 am yesterday. This ran over debris from a glide avalanche last week. Photo: Ryan Lewthwaite
Cornices: Monday’s snow and wind made already large cornices noticeably larger. We haven’t seen an active day of widespread cornice failure yet this season. This just means they continue to grow and creep closer to failure. Warming temperatures this week could act as a catalyst for cornices to fall. Keep a wide berth both on ridges and when moving below corniced terrain.
Wind slabs: A brief period of wind toward the end of the storm Monday likely built isolated wind slabs in steep leeward terrain in the Alpine. These may be touchy, particularly on unsupported slopes and during the heat of the day and/or when the sun is warming them. They are sitting on a stout melt freeze crust. There is very obvious wind loading, including cross-loaded slopes from the storm.
Yesterday was a mixture of overcast skies and sunshine. Winds were mostly light and easterly. Temperatures were the mid 30Fs to upper 40Fs. Overnight there was rain/snow showers.
Today is forecasted to be mostly cloudy with rain/snow showers and the rain/snow line at 2400′. Temperatures will be in the mid 30Fs to mid 40Fs. Winds will be easterly 25-35 mph. There may be some clearing this afternoon and an increase in winds as the front passes.
Tomorrow is a break between storms and then another system rolls in on Friday with hopefully a cooling trend over the weekend.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||40||rain||.1||125|
|Summit Lake (1400′)||39||0||0||40|
|Alyeska Mid (1700′)||35||rain||.2||114|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||31||SE||20||43|
|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: email@example.com
|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.