Turnagain Pass Avalanche Forecast

No avalanche activity was seen or reported yesterday. The last known avalanche in our forecast zone was a natural 1-2′ slab Thursday on Raggedtop near Girdwood.

Although a potent weather system is entering central Alaska from the Bering today, we will be far enough to the south that it looks to just brush us by. Only a trace to 1″ of snow is expected by sunset (8:49pm!) with a chance for 2-4″ tomorrow. The mountains north of Girdwood may see larger amounts this evening through tomorrow (6-12″). Ridgetop winds will be on a slow rise from the south today and may hit averages near 20mph by 6pm and continue rising into tomorrow with averages near 30mph.

Until we receive enough snow/wind to create a new avalanche issue, we remain concerned with old buried weak layers in the top 3′ of the snowpack. These continue to show enough signs of instability that we can’t forget about them. Hence, there is still a chance a person could trigger a persistent slab avalanche. Here are some things to keep in mind:

• ASPECT: Sun crusts are present all the way to ridgetops on southerly aspects, including many east and some west aspects. It’s no surprise those slopes are being avoided and instead the northerly shaded slopes, the ones with the soft surface snow, are getting the attention. Crusts can change the slab character and make triggering a slab more difficult. Today, winds and cloud cover should keep the sun crusts from softening and so it will be those shaded aspects which are most concerning.
• Of those shaded aspects, watch for steep slopes/terrain that has been previously wind loaded. Prior wind loading over these weak layers has been been the culprit in the Raggedtop avalanches near Girdwood and the Summit Lake avalanches from last week.
• Listen/feel for whumpfing in the snowpack and watch for any other signs of instability. Chances are these will be slim to none and simply knowing there is some funny business is the main point. Girdwood Valley, south of Turnagain Pass and Summit Lake have been the regions showing the most unstable snow.
• As always, use good travel protocol, and consider the consequences if an avalanche does occur. Watch your partners, expose only one person at a time and know your save zones.

Wind Slabs:  With a bump in winds later today, watch for any snow that might get blown into small shallow wind slabs in the high terrain. With the winds from the south and surface crusts on south aspects, it might be difficult for the wind to pick up much snow. However, terrain channeling can cause winds to shift directions and so be sure to watch for any active loading.

Sluffs:  As always, watch your sluff on steep slopes with soft surface snow (shaded aspects today).

Tincan seen from Seattle Ridge yesterday. It’s a bit difficult to see, but there are many recent tracks in the shade while the sunny slopes sport mostly older tracks. It’s that time of year that we are all playing the aspect. 4.2.21.

Snow pit on the east face of Seattle Ridge, just north of Repeat Offender slide path. Pit shows a thin weak layer of buried surface hoar and facets 16″ down that took a lot of force to fail, but when it did it propagated. This means the layer is difficult to trigger but could produce an avalanche if it failed. 4.2.21.