Turnagain Pass Avalanche Forecast

Seward Highway: Several large natural avalanches ran yesterday morning along the Seward Highway near Girdwood.

Seattle Ridge: Debris from another round of natural activity was visible from the road along Seattle Ridge. Most of the avalanches appeared to be loose wet avalanches, but some debris piles were wide enough that they likely came from wet slab avalanches.

Fresh avalanche debris along the Seward Hwy near Girdwood yesterday. Photo: Matt McKee. 04.14.2021

Avalanche conditions are still dangerous today following heavy snowfall, strong winds, and rain up to around 1700′ yesterday. Since Monday evening, we have seen the following precipitation totals at weather stations in the area:

• 15″ snow equaling 2.2″ snow water equivalent (SWE) at the Center Ridge Snotel station (el. 1880′)
• 34″ snow equaling 3.7″ SWE at Alyeska’s mid-mountain station (el. 1700′)
• 2″ snow equaling 0.7″ SWE at the Summit Lake Snotel station (el. 1400′)

With mixed rain and snow approaching these weather stations, we expect significantly higher storm totals at higher elevations. Snow surface conditions will change drastically with elevation today, but conditions will be dangerous from valleys to ridgelines. At lower to mid elevations, the combination of rain on snow and over 24 hours of above-freezing temperatures will increase the likelihood of triggering wet snow avalanches. At elevations above 1700′, higher snow totals will make it possible to trigger larger avalanches. Strong winds through yesterday night have been creating wind slabs up to 2-3′ deep that will be sensitive to human triggers. Slab depth will increase with elevation, where storm totals and wind speeds were higher.

The avalanche conditions are complicated today, but the travel advice is simple: cautious route-finding and conservative decision-making are key. Whether you are dealing with a wet slab, a wind slab, or a storm slab, it is likely a person can trigger an avalanche in terrain 35 degrees or steeper today. With all of the recent snow, avalanches can be large today and have the potential to run into lower elevations. This means it will also be important to be aware of the avalanche hazard from steep slopes above you.

As we head into the weekend, we are expecting to see sunny skies and the warmest temperatures of the season. This is going to result in elevated avalanche danger for the next few days as the snowpack heats up and we start to see things falling apart. Be sure to stay tuned for updates as we head into what is feeling a lot more like springtime.

Loose snow avalanches: It is very likely a person will be able to trigger loose snow avalanches in steep terrain today. These may be dry at higher elevations and wet at lower elevations. Be on the lookout for natural activity as well, especially if the sun pokes through the clouds later in the day.

Roof avalanches: Some buildings in Girdwood have already been seeing the massive piles of snow slide off of their roofs with warm temperatures and rain in town. This will continue to be a hazard today, so be sure to keep an eye on kids and pets, and be careful where you park your car.

Debris from natural avalanches above the Bertha Creek campground on Tuesday. Photo taken 04.14.2021.

Very soggy conditions at the top of Turnagain Pass yesterday. The snow turned into rain shortly after the picture was taken. 04.14.2021

The combination of heavy snowfall, strong winds, and rain has applied a load that will test the strength of the buried persistent weak layers that we have been dealing with for some time now. With a weak refreeze overnight, we are likely to see additional meltwater moving through the snowpack, further contributing to poor stability. Avalanches triggered at the new/old snow interface (see Problem 1 above) will have the potential to step down to these deeper weak layers, creating larger avalanches. The potential for these persistent slab avalanches is just one more reason to avoid steep terrain today, and be mindful of crossing runout zones below steep avalanche paths above.