Turnagain Pass Avalanche Forecast

Strong northwest outflow winds are still at work this morning building fresh wind slabs 1-2′ deep that will be easily triggered today. Winds have been blowing 20-35 mph since yesterday morning, with gusts as high as 76 mph near Girdwood, 56 mph near Turnagain Pass, and 68 mph near Summit Lakes. As of this morning weather stations are still showing sustained westerly winds at 15-20 mph, which are expected to continue for most of the day before calming this afternoon. Recently wind loaded slopes will remain touchy through the day.

There are a few nuances to consider with these strong northwest winds:

• Although the general direction is out of the northwest, we tend to see channelized flow through local terrain, with lower level winds blowing up the Six Mile Creek drainage, then wrapping around the south end of Turnagain Pass. This usually leads to southerly winds on the skier side of the pass, with northerly winds over Seattle Ridge.
• It is looking like Seattle Ridge and Summit Lakes will see the strongest winds today, which means it will be more likely to find sensitive wind slabs in these areas.
• It will be possible to travel out into the middle of a stiff wind slab before triggering it, increasing the chance of getting caught if you do trigger something.

Today it will be important to identify and avoid recently wind loaded slopes. The most likely places to find these will be in gullies, below convexities, and below ridgelines. With the winds blowing as hard as they have been, keep in mind wind slabs are likely forming further below ridgelines than you might normally expect. Keep an eye out for the telltale signs of instability- shooting cracks, collapsing, and new avalanche activity. It is also important to remember that a relatively small wind slab avalanche could trigger a big avalanche on weak snow lurking below the surface. More on this in problem 2 below.

Snow blowing off the ridge at Taylor Pass yesterday, loading the east side of the pass. 12.23.2021

We are slowly starting to gain some confidence in the weak snow buried 2-5′ deep in most areas in the forecast zone, but we aren’t in the clear just yet. This round of strong winds is putting a heavy load on some slopes, which adds stress to those weak layers and nudges the needle just a little higher up the likelihood meter for today. As mentioned previously, a relatively small wind slab triggered near the surface has the potential to step down to these deeper persistent weak layers.

The most likely places to run into trouble with a deep persistent weak layer are areas with a thinner snowpack. You can think about this on a regional scale, with thinner conditions on the south end of Turnagain Pass towards Lynx Creek, Silvertip, and Summit Lakes. You can also consider slope-scale differences, with likely trigger points at thin spots on a slope, maybe with some rocks sticking out. These avalanches are becoming more difficult to trigger, but I wouldn’t feel comfortable stepping out into bigger terrain just yet, especially on the heels of a big wind loading event.

Click here to view yesterday’s snowpack summary from Taylor Pass if the video doesn’t load in your browser.