Juneau Area Avalanche Advisory
2006-05-14
Mt. Stewart
by Bill Glude, SAAC Observer
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We went high on Mt. Stewart today to check the progress of the spring thaw that finally arrived this week. On high shaded-aspect slopes, we found that only the surface 15 cm has wetted out so far. The rest of the snowpack has reached freezing and is moist, but it has not made the transition to melt-freeze grains.

We found some buried graupel that was still fairly weak, releasing on a second, harder jump at average shear quality in our sole AK Block test (AK5Q2).

Sunnier slopes showed more signs of a warming snowpack, with glide cracks opening and sometimes releasing as glide avalanches. Wet point releases and cinnamon rolls were common.

The large recently-formed cornices are dropping now as they thaw, and some have triggered small slabs on the weak layers. Others simply released large sluffs containing many big cornice chunks.

Travel conditions were slushy but good. Backcountry travelers should stay out from under cornices and the slopes below them, stay off of glide plates and clear of their runouts, and expect to trigger wet sluffs on thawing slopes.

The avalanche cycles going on now do not generally threaten developed areas, unless a large glide plate releases or a big cornice drops above them.
Field Notes
Photos
Glide cracks are active throughout the region now. We have not had many of them at all this season, but they have appeared over the last week in all the usual places. The one just left of and below center in this photo is on the slopes of Heintzelman ridge as seen from the COSTCO parking lot.
More glide cracks, this time on rocky slopes on Mt. Bullard. The opened cracks and the rumpled glide plates are clearly visible. While we were coming down from fieldwork near Eaglecrest today, a glide avalanche loudly let go on the slopes above the lower cross country loop. When glide plates release, they create full-depth avalanches. It's best to stay off the glide plates and out from under glide areas whenever glide areas are active.
Large cornices were conspicuously absent here for most of the winter, but they built rapidly in the steady snowfall and SE winds of the last few weeks. While some have let go fully or partially, as seen from the chunks below the skin track in this photo, many massive overhanging ones still threaten such routes as this. As the weather warms the cornices are dropping, often triggering large avalanches when they do.
The upper portion of the Eaglecrest ski area still has good snowcover, better than it had all winter.
Even small chunks of cornices can trigger avalanches like these recent shallow slabs on Mt. Stewart.
Marc Scholten enjoys the descent on fat skis in slushy snow. On shaded aspects above 750m, only the top 15 cm of the snowpack has wetted out, but it is quite wet due to the last few days' warm weather. Surface sluffs are easily triggered.
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