Turnagain Pass

Good morning. This is Kevin Wright with the Chugach National Forest Avalanche Information Center on Saturday, January 14th at 7am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

BOTTOM LINE

The avalanche danger is MODERATE for small wind slabs and loose sluff. Pockets of CONSIDERABLE danger may be present in specific areas with recent or current wind loading. Several large natural avalanches yesterday in Summit have me back on guard with the current conditions.

AVALANCHE DISCUSSION

The conditions are more complicated right now than I would have expected, with a couple of specific problems and some issues that are still not fully understood. To start off, the big obvious sign of avalanche problems showed yesterday in Summit when a natural avalanche came out in the afternoon and slid all the way to the highway. Some observations from Summit also came back reporting “no red flags”, illustrating contrasting realities of stability and significant variation in the conditions depending on location. There are anomalies in the snowpack today that might be different from what you are finding. At least 3 unusually large avalanches have happened since Tuesday, 2 were triggered by explosives and one was natural. The common theme was all three were fast movers and traveled far.

Seward Highway DOT will be doing avalanche hazard reduction work in the Summit lake region to mitigate any residual risk for the highway. Expect intermittent road closures today between 10am and 2pm. Check http://511.alaska.gov/ for the latest road information.

With limited information we believe that wind loading had a significant component to this larger natural avalanche. The light density surface snow found through the region is very easily moved by wind. Yesterday areas around Turnagain Pass and Girdwood got little wind, while Portage and Summit got stronger wind with obvious plumes off the ridges above 3000 feet. Expect local variations and be prepared to change your travel plans if you find dangerous conditions. Again today my confidence in placing a blanket danger rating on the entire region is low because there is significant spatial variability present in the mountains right now.

The observations through Turnagain Pass yesterday were consistently showing limited problems. Small loose sluffs in the light density surface snow were fairly common on steep slopes. A couple of very small skier triggered slabs were found by skiers on Tincan. Snowpit tests are finding moderate shears on a low-density layer below the snow from Tuesday’s storm. The rime crust from Sunday is fairly widespread, but showing limited reactivity.

MOUNTAIN WEATHER

Cold and clear weather will persist today. Temperatures are currently near zero at many of our weather stations. Wind is variable again today. A cold North wind is expected with some areas at higher elevation reaching gusts into the low 40s.

Wind will be the most significant factor today that could contribute to avalanche conditions. Pay attention to the wind where you are traveling and how it is affecting the surface snow.

CNFAIC Weather Page and the NWS forecast

Wendy will issue the next advisory Sunday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.