Juneau Area Avalanche Advisory
2006-04-11
Mt. Stewart
by Bill Glude, SAAC Observer
Home Advisory Home Send Us An Observation Next Advisory Previous Advisory
Text
We were back on Mt. Stewart again today. The spring warming has been progressing very gradually this year. Though the snowcover is disappearing rapidly below 500m and is thin and rotten to 600m, above that elevation on shadier slopes it remains dry and unthawed below the top 20cm.

The deeper facet layer we had been testing a week ago has strengthened as the facets rounded over time, and that 5cm layer showed no shears in our tests today.

The 5 to 10cm of moist new snow over icy melt-freeze sheared off easily but irregularly on approach (AK2Q2, CAK2Q2, RB2Q2) on 38° and produced wet point releases on steeper slopes. The 100cm layer of low density rounds formed a second weakness that cleanly and rapidly sheared the top 30cm of the snowpack on the second hard jump or multiple jumps (AK6Q1, CAK5Q1, RB6Q1).

Our test blocks had a classic distribution of values that is often showing up in our tests. The standard AK Blocks agreed with the Rutschblocks, their smaller size just balancing the uncut back, while the cutback CAK blocks with their smaller size and cut backs were one step weaker.

Weak layers remain in the snowpack and it has not yet gone through a full spring thaw. While loading is not that great right now, the surface layer presents a hazard from wet sluffs and might transition into wet slabs if it warms rapidly enough. Wet slabs might rip out the 100cm layer or other deeper weaknesses.

Large slabs reaching developed areas are unlikely, but backcountry travelers should take care. Continue to watch for rapid warming, heavy rain to elevation, or heavy new snow.
Field Notes
Photos
The snow level today was about 350m, at the base elevation of Eaglecrest. Above 600m, five to ten centimeters of fluffy but moist new snow was very poorly bonded to a slick, hard-frozen melt-freeze crust. There were numerous small wet point releases, and the surface layer was so weakly bonded that it was hard to make a climbing traverse on skis due to the constant slippage as the snow slid out from under the edges of the skis. We could easily trigger wet point release avalanches on slopes above 40°.
As the sun broke through the clouds and warmed the new snow, it rapidly became moist, stuck to slimbing skins, and forward motion pushed a plug of snow ahead of the skis.
Snowballs rolling downslope were not yet growing into large cinnamon rolls, but the small ones that were running produced some beautiful track patterns.
When the sun broke through, it revealed tall cumulus clouds and blue sky above the peaks.
The new snow was not quite wet enough to sluff on these slopes, but the tracks show its moist, chunky nature and the wide skid shows how slick the underlying melt-freeze crust was.
Home Advisory Home Send Us An Observation Next Advisory Previous Advisory