Turnagain Pass Avalanche Forecast

Seattle Ridge: There was another large human-triggered avalanche in Main Bowl yesterday that carried a rider and his machine. The person was able to deploy an avalanche airbag and ended up on top of the debris. This is the third large human-triggered avalanche in Main Bowl in the past week. More details here.

Snowmachine-triggered avalanche on Seattle Ridge’s Main Bowl yesterday. The avalanche was estimated at 3′ deep and 1000′ wide. Rider was caught and carried, but ended up on top of the debris after deploying an avalanche airbag. Photo: Jacob Ohms. 12.08.2021

After a brief quiet period yesterday, a strong weather system is moving back in today. Easterly winds are expected to increase to around 30 mph in Turnagain Pass and 40-50 mph near Girdwood, with gusts as high as 60-70 mph. Heavy snowfall is also expected to begin mid day, and there is already plenty of soft snow on the ground ready to be blown around as soon as the winds pick up. Large natural avalanches 1-2′ deep will become likely, with human-triggered avalanches very likely. These fresh wind slabs will be building on top of an already dangerous snowpack that has been producing very large avalanches for the past week. It is likely that an avalanche triggered in the new and wind-transported snow at the surface will step down to make an even bigger avalanche failing on weak, faceted snow that will be buried 4-6′ deep. More on this in problem 2 below.

Conditions will quickly become dangerous when the storm arrives. If you do try to get out ahead of the storm, be ready to get back down and out of avalanche terrain quickly and head down to the parking lot when you notice the weather start to act up.

Here comes the next round! It is looking like Turnagain Pass will get hit hard by this round. The storm is expected to intensify during the day today and continue overnight. Graphic courtesy of  NWS Anchorage.

We are dealing with a really dangerous snowpack right now. The weak faceted snow buried 3-4′ deep on top of the Halloween crust is still producing avalanches, with another large human-triggered avalanche carrying a snowmachiner in Main Bowl yesterday (details). As the wind and snow starts to pick up today, we can expect to see big avalanches failing on that weak layer. This layer is nothing to mess with. It has consistently been producing human-triggered avalanches up to 1000′ wide and over 3′ deep (Main Bowl 1, Main Bowl 2, Main bowl 3, Eddie’s, Magnum), and it was responsible for several large natural avalanches during the most recent storm on Monday and Tuesday (see the photo of Pyramid below). Sometimes these layers can be difficult to predict, but right now it is quite clearly a reactive layer that is ready to make big avalanches.

Heavy snowfall and strong winds will be testing this layer with a big load today, and it is likely we will see natural avalanches running to valley bottoms as this layer gets pushed to its breaking point. As mentioned in problem 1 above, a relatively small avalanche failing in the new snow has the potential to trigger a deeper avalanche on this weak layer. Keep this in mind as the weather picks up today, and make sure to get back to the parking lot when you start to notice the weather getting nasty.

Large crown on the east face of Pyramid. The avalanche released on Tuesday during the strong winds on the tail of the last storm. Similar activity is likely as winds and snow pick up today. 12.08.2021

We saw the same dangerous setup on Sunburst yesterday that that has been producing large avalanches across the advisory area. See the video below for a quick summary (link here).