Turnagain Pass Avalanche Forecast

‘Twas the night before Christmas, when all through the hills,
Neither skier or rider was looking for thrills.
With a blast of wind and light snow falling,
There were hopes of blue skies in the early chill morning.

Happy Holidays everyone! And, that’s right, many folks are hoping for some clearing skies today after a quick pulse of moisture and wind moved in last night. This brought 4″ of new snow to the mid elevations and ~6″ to the higher elevations. Ridgetop winds picked up from the east averaging 25-35 mph for a period of 8 hours last night with gusts to 56mph on Sunburst. Since then, winds have been steady around 20mph with gusts near 40mph; where they are expected to remain today. With around 6-10+” of existing loose snow on the surface and other 6+” from last night in the high elevations, we can expect to find some wind loaded slopes and touchy wind slabs today. The good news is, new wind slabs should be easy to identify and relegated to the higher terrain. Seeking out areas without wind effect will be your best bet for fun riding conditions and avoiding a wind slab avalanche.

Wind slab avalanches:  Triggering a fresh wind slab is the main concern today. If skies clear enough for travel into the bigger terrain watch for:

• Slopes or gullies with fresh wind deposited snow.
• Cracking in the snow around you and stiff snow over softer snow.
• Recent avalanches? There could have been some small natural wind slabs overnight. Keep on the lookout for these signs.
• Wind slabs could be anywhere from 1-2 feet thick pending the wind loading.
• Older, stubborn, but larger wind slabs could be lurking from the very strong winds on Tuesday.

Cornices:  As always, watch for cornices and give them a wide berth.

Loose snow sluffs:  If you are lucky enough to find a slope without wind effect and lots of loose snow, watch your sluff.

Warm-up Bowl (-1 Bowl) avalanche from Wednesday 12/23 – UPDATE:
We were able to get a look at the large avalanche triggered on the backside of Seattle Ridge yesterday. This slide was 2-4’+ feet deep, 1,000′ wide and ran around 800 vertical feet. It was triggered by a snowboarder who was the 5th person down the slope. The boarder deployed their airbag and when the debris settled, was buried up to their neck. They are thankfully OK and a few more details can be found HERE (from the boarder involved) and HERE.

Much of the crown face can be seen in the photo below with its wide propagation. This did turn out to be a large wind slab that had not bonded yet after Tuesday’s 2-3′ of snow and extremely strong winds. The weak layer was precipitation particles (stellar crystals) and not a persistent weak layer – however, these stellars can act like a persistent grain type for a few days before bonding, hence the wide propagation. Today is day three, and there just might be a lurking larger wind slab not yet bonded under the new smaller slabs formed overnight.

Warm-up Bowl avalanche from Wednesday 12.23.20. Photo: Anonymous

Crown face of one section of the slide. The crown was 2′ thick here but grew to over 4′ in sections. Photo taken 12.24.20.

What to do about those old October facets near the ground in the shallow snowpack zones? In Summit Lake and the central Kenai Mtns the snowpack is much thinner than Turnagain Pass. This area is outside our forecast zone, but we want to be sure folks know the difference in snowpack. As Aleph mentioned yesterday, this layer continues to show less and less reactivity over time and triggering an avalanche releasing near the ground is unlikely. Because of all the crusts in the mid-pack from 2,500 and below, this issue would be above, in the Alpine, where no crusts exist.