Turnagain Pass Avalanche Forecast

There were no known slab avalanches triggered either naturally or by people yesterday. However, there was not a lot of traffic out testing the slopes. The photo below is of a natural wind slab avalanche from Monday during the stormy weather on the backside of Seattle Ridge in Zero Bowl. Believe it or not, there were several small sluffs triggered midday by the sun warming the top 3-4″ of light new snow, also pictured below.

Wind slab avalanche, likely triggered by a chunk of cornice breaking off, during the storm on Monday, 1.10.22. Photo taken 1.11.22.

Shallow loose snow sluffs triggered by the sun warming the top 3-4″ of new low density snow. 1.11.22.

After a pleasant break in storms yesterday with a bit of sunshine poking through, another weather system has moved in overnight. This has brought increasing easterly winds, light snowfall, and continued warm temperatures. Only 1-2″ of snow has fallen in Girdwood and Turnagain Pass by 6am this morning but another 1-3″ may fall through the day (light rain to 300′ or so). The easterly winds along the ridgetops will be our main concern. They increased to 20-25mph overnight and should continue to rise near 30mph with stronger gusts today. Hence wind slab avalanches forming in Monday’s storm remains the avalanche problem.

The winds today are from the same direction as those on Monday when 10-12″ of new snow fell at Turnagain. That means wind slabs will just be getting a bit bigger than they were. They are sitting on a mixture of weak faceted snow and crusts that was the old surface and may not be bonding very well. Interestingly enough, yesterday we found Monday’s snow to not be very reactive on test slopes and in pits despite the fact they were sitting on weak snow – maybe due to slabs being too thin and not quite heavy enough. Either way, crusts and facets under a slab are not something to write off without more data and we should keep a conservative mindset when approaching the bigger terrain.

Things to watch for if you are headed out today:

• Active or previous wind loading? Any wind loaded slope is suspect to slide.
• Cracking in the snow around you? Or collapsing (whumpfing) in the snow under you?
• Any signs of recent avalanches?
• Stick your hand in the snow and see how much of Monday’s snow is on that old crust. That’s the size of a potential slab that could be triggered.

Storm slabs:  In areas that have not seen the winds, keep in mind there still may be some lurking storm slabs that we could trigger. These should be on the shallower side (10-12″) and are associated with Monday’s snow over the crust as seen in the video below.

In this snow pit on Seattle Ridge, the new snow wanted to slide off the crust easily when pulled, but at the same time, didn’t want to propagate in our pit tests.

Lower elevations:  Monday’s storm created a crust up to 1,500 – 1,800′ and triggering an avalanche is unlikely from around 500′ to 1,500′ due to the crust. What is possible is an avalanche releasing from above and running into this zone.

Rain fell as high as 1,500′ on Monday creating a crust with clearly seen runnels in the 500 to 1,500′ elevations band. Seattle Flats, 1.11.22.