Turnagain Pass Avalanche Forecast

There were several fresh piles of avalanche debris along the base of the SW face of Seattle Ridge yesterday but the crowns had already been filled in by wind transport so it is hard to say exactly how old those avalanches are. Our best guess is that they were triggered naturally by wind loading within the last 2 days. A group digging snow pits in the lower Tincan meadows observed an avalanche in motion in Todd’s run on the N aspect of Tincan at about 3500′ (see ob here). They could not tell whether it was a dry loose or wind slab from their vantage point, but based on the location they suspected it was a small wind slab which released naturally.

Example of debris on SE aspect of Seattle Ridge with a possible crown on the upper shoulder above the gully feature. Photo 3.3.23

The good news is that even after several days of NW outflow winds there is still soft snow to be found in Turnagain Pass. However, there are a lot of areas along ridgelines and more prominent features where the soft surface snow has been blown into firmer wind affected surfaces which could potentially be harboring wind slabs on leeward slopes. We found a few small test slopes that were producing shooting cracks yesterday but they were pretty stubborn to release under the weight of a skier. In areas where there has been more recent wind loading, like along upper elevation ridges and cross loaded gullies, these wind slabs could be more reactive to human triggers and human triggered avalanches 1’+ deep are likely. In areas experiencing active wind loading today natural avalanches are also possible.

The NW outflow winds that have been impacting the forecast area over the past several days are expected to decrease today. Overnight the wind speeds continued to average 10-20 mph with gusts to 30-40 mph, with the strongest winds in areas exposed to Turnagain Arm and other favored locations for gaps winds. Today the winds speeds are expected to decrease to 5-15 mph with gusts to 25 mph around mid day. This should decrease the chances of natural and human triggered avalanches in the second half of the day, but it will still be possible to find a lingering wind slab.

In areas protected from the winds dry loose avalanches (aka sluffs) are likely in steeper terrain. In addition all the recent winds combined with sun could make cornices more likely to fail today. Keep an eye out for cornices that are being actively wind loaded and receiving direct sunlight today.

Shooting crack on a cross loaded gully around 2000′ on Sunburst yesterday. Photo 3.3.23

Surface conditions ranged from firm to soft even in areas with visible wind texture on the surface yesterday. Photo 3.3.23

There are a few persistent weak layers in the upper 2-3′ of the snowpack that could produce larger avalanches in isolated areas. Since it has been a few days since the last significant snowfall the chances of these layers being reactive is decreasing. The most likely place to find a reactive buried weak layer is in parts of the forecast area that have a thinner snowpack, like on the southern end of Turnagain Pass (see recent ob from Pete’s N), Summit Lake (outside the forecast area), or in the Crow Creek area. We will continue to monitor these weak layers but don’t expect them to be a significant issue until we get another storm.