ACCIDENT AND RESCUE SUMMARY
A party of six left the Sunburst parking lot in Turnagain Pass the morning of March 17 with the intention of skiing the southeast face of Pastoral Peak (elev 4764’). They followed the Taylor Creek drainage up and over Taylor Pass and on to Pastoral Peak ascending via the west ridge. The party decided to descend from a notch at 4000 feet below the true summit. Skiers #1 and #2 skied first to the bottom, one at a time, then skier #3 entered, did one jump turn, and triggered the slide. The avalanche released about 20 feet above skier #3 and carried her 1500 feet to the flat valley bottom floor. The crown face was 10-18 inches deep and 30 feet wide. The slab ran on an old hardpacked icy surface and over several rock bands, stepping down to the ground in some spots in the middle of the bed surface. There was no obvious wind loading on the face. Skiers #4 and #5 skied down the bed surface to initiate a search while skier #6 stayed at the top. Using an Ortovox M1, skier #4 was able to get within 8 feet of the burial location when he saw a glove sticking up through the surface of the snow. Luckily a hand was attached to this glove, and he quickly dug skier #3 out without having to probe. Total elapsed time was about 20 minutes. Skier #3 was in a prone position about 12 inches under the surface and breathing upon extraction. She was using an alpine touring setup and both of her Fritschi bindings released; however, she was using leashes for the descent and those did not break free keeping her skis loosely attached. She was also wearing pole straps; one broke free and the other did not. The extent of her injuries was a bruised leg. Skiers #1 and #2 skied down to the Center Creek drainage where they ran into some snowmachiners (riding in a non-motorized area). The snowmachiners rode up to the accident site and gave skier #3 a ride out to the Johnson Pass trailhead while towing the other skiers behind the sleds.
After record setting snowfalls in December and January, the month of February started off with rain to 2500 feet and two days of temps near 50 deg F up to 4000 feet elevation. This created rain crusts and melt-freeze crusts throughout Turnagain Pass on all aspects and elevations. Unseasonably cold weather and periods of high winds dominated southcentral Alaska through February and March. Our snowfall total in Turnagain Pass for February was 20% of normal. Widespread surface hoar and near-surface facets formed above and below these crusts.
Our last significant snowfall was March 7 when we received 16-24 inches of snow and 1 inch SWE. We had very strong winds predominantly out of the north and west on March 13th with large snow plumes visible on most peaks and ridgetops.
ADVISORY FOR MARCH 17, 2007
Good morning St Patrick’s Day travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday, March 17th at 7:30 am. This notice will serve as a general backcountry avalanche advisory Wednesday-Sunday for the Turnagain Arm area. Local variations always occur. If this advisory is not current we are probably experiencing technical difficulties because the internet is down. Remember you can always call the hotline at 907-754-2369.
Weak low pressure in Prince William Sound continues for the weekend. Currently skies are clear and winds are calm at sea level and gusting into the lower teens at ridge top elevations. Winds are forecasted to pick up out of the north and west. The National Weather Service is also forecasting a 40% chance of snow for tomorrow. Current temps range from -9 in Portage to 10 degrees F. midway on Alyeska.
Today natural avalanches are unlikely, and human triggered avalanches are still possible on terrain steeper than 38 degrees.
Our primary avalanche concern today focuses on wind slabs present in many alpine locations. Strong winds early in the week stiffened most snow surfaces and created hard wind slabs on cross loaded and leeward aspects. Although we haven’t seen very thick wind slabs, I think they may be a foot thick in some locations. These wind slabs are not bonded very well with last weeks snow and have a drum tight character with associated shooting cracks. These wind slabs may also trigger our secondary concern!
Our second concern today is the deeper slab instabilities. Last weeks 16-24 inches of snow has settled and created a slab on a series of weak layers. These weak layers are responsible for at least 7 human triggered avalanches over the last 7 days. These slabs are a foot to two feet thick and 50-150 feet wide. We have seen stability improve on sun affected aspects, but north facing or shaded aspects remain questionable.
Watch out for wind slabs near ridges, ribs, trees, rocks bands, or other terrain features, especially on slopes steeper than 38 degrees.
Careful route finding and good travel rituals should remain a top priority today. Lots of tracks exist out there; don’t let uptracks and highmarks lull you into thinking the snowpack is stable.