Wind Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 1–2
Yesterday's storm was more blow than snow, with ridgetop winds averaging 20 to 30 mph from the southeast and gusts up to 60 mph. Girdwood and Seward were favored with 2-5" of new snow while Turnagain Pass and Summit Lake only received a trace to 1" of new snow.
Wind slab avalanches up to a foot deep near treeline and above are the main concern today. During the past two weeks of cold and clear weather, a lot of weak snow formed on the surface, including widespread surface hoar and faceted snow, which is being buried by the new storm and wind transported snow. Wind slabs that form on top of this weak snow could release on lower angle slopes and be more sensitive to human triggers than typical. You can identify fresh wind slabs by looking for slopes with active wind transport, hollow feeling pillows of snow, and shooting cracks on the snow surface. Probing with a ski pole, using hand pits, or checking for wind slabs on small test slopes can be useful ways to assess the distribution and sensitivity of wind slabs before entering steeper terrain.
In addition, dry loose avalanches or sluffs are likely today in areas favored with more precipitation during yesterday's storm. The combination of new snow on top of the weak old snow surface can form fast running sluffs with more volume than typical.
Glide avalanches and glide cracks have been observed across the region in the past two weeks. These are unpredictable and can cause very large and destructive avalanches, so we recommend avoiding spending time underneath open glide cracks.
Cornices have also grown very large at this point in the season and can fail naturally during periods of active wind loading. Try to avoid traveling underneath cornices while they are being loaded and give them a wide berth when traveling along ridgelines.
Snowfall forecast for Saturday from NWS Anchorage.