Turnagain Pass

Yesterdays rain and rapid warming contributed to numerous large natural avalanches being reported in upper Girdwood and Crow Creek Valley, through the Portage Valley and near Summit lake.  There was also one skier triggered slab avalanche on Tincan above treeline on a small(ish) rollover. This slab was 2 feet deep and 100 feet wide running 150 feet down. No one was caught.

With limited visibility yesterday, it’s unknown but suspected that many of the natural avalanches initiated in both alpine and treeline elevations, with debris running to valley bottoms in some cases.

The Five Sisters slide path in Portage Valley

Happy New Year from all of us at the CNFAIC!

Yesterday the advisory area experienced a rapid warming event in conjunction with rain up to 2200′.  This additional load tipped the balance on many steep slopes causing numerous large avalanches.  Last night, winds picked up and rain shifted to snow as the temperatures suddenly dropped into the teens and snow fell to sea level. Over the past 24-hours the Alpine has seen 15 – 25″+ of new snow in Girdwood Valley and Turnagain Pass. Summit Lake is estimated at 8-10″ of snow in the Alpine while Portage Valley was the big winner with over 4′ of snow near Portage Pass.

Today, temperatures will move toward the single digits and winds should blow from 15-25mph. This may contribute to the high wind effect over the past day and continue to actively load slopes on the lee of ridges and gullies. The new load of snow from the past few storms sits on top of weak snow 2-3′ deep along with a documented weak layer of buried surface hoar from Solstice.  Although we have cooling temperatures, the snowpack is still adjusting to the load and large slab avalanches are likely to be triggered. The snowpack set-up such that remote triggering a large slab is possible. This means triggering an avalanche from below, above or adjacent to the slope.

Very cautious route-finding is essential today. There were several observers who experienced long shooting cracks and large wumpfing yesterday and this will likely be the case again today.  These are clear indicators for us to reconsider our route and plan. These and other red flags should be up front in our minds:

• Signs of recent avalanches
• Whumfing in the snow under you (collapsing of the snowpack)
• Shooting cracks in the snow around you

Cornices:  Strong winds and new snow have further developed the cornices throughout the region. With such varying layers and densities within the snow and wind cycles, it’s prudent to give cornices extra caution- limit your time beneath them, and give them a wide margin.