Turnagain Pass Avalanche Forecast

With sunshine on tap, Friday of Spring break week and a fresh blanket of snow, we can expect a busy day on the playground today.  Don’t lose sight of the fact that this week’s storm came in on a very weak surface and was accompanied by winds easily strong enough to transport the new snow.  As you gain in elevation and leave the shelter of the Forest and valleys below, expect to find wind slabs sensitive to human triggers.  My group was easily able to initiate wind slabs on small test slopes in the Lynx Creek area near tree line yesterday.  Similar results were found on test slopes in the Girdwood Valley.  These were breaking on the new/ old interface (18-24” down) on small, steep wind loaded slopes.  Look for stiffer snow and/ or shooting cracks from your skis or snowmachine to identify where the wind has left its mark.  Pay particular attention to unsupported slopes (convexities) and cross loaded gullies such as those on the front face of Seattle ridge.  These may prove a bit more stubborn today but are likely to be easier to initiate (and deeper) as you gain in elevation.  Quick hand pits or jumping on small non-consequential test slopes can further help you suss out these wind slabs and gauge reactivity.

Storm totals varied from 8” on the south end of Turnagain Pass to 16”+ on the north end between Wednesday morning and yesterday afternoon.  Winds were a constant and strong enough to easily transport the low-density storm snow into wind slabs above 1,000’.  The wind shut off pretty abruptly yesterday afternoon, though not til after some damage was done in the tree line and above elevations.  Today will be a day to sniff out any wind slabs and actively manage your terrain and your group.  As we roll into the best (and busiest) days of the season, communicate with, and be cognizant of adjacent parties, exposing only one person at a time to avalanche terrain.

A note on cornices:  They’re yuuuge right now.  Avoid these backcountry bombs as cornices are likely tender and may be easy to trigger from above today.

Persistent slabs: We’ve got a few weak, persistent layers deeper in the snowpack that we haven’t forgotten about.  There is a chance that a wind slab avalanche triggered near the surface overloads the older weak layers in the snowpack and steps down, creating a larger avalanche. This is another reason for extra caution today.

Sluffs: Steep slopes that are sheltered from the wind have a foot or more of new soft snow and a few inches of pre-storm facets. It will be easy to trigger dry loose avalanches (sluffs) in steep terrain unaffected by the wind.

Shooting cracks are a sure fire way to know you’ve found a wind slab.  photo: Paul Wunnicke

Small wind loaded test slope intentionally triggered by a snowmachine in the Lynx Creek drainage.