Juneau Area Avalanche Advisory
2006-02-25
Showboat - Troy Area
by Bill Glude, SAAC Observer
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Today we traveled in the Showboat and Mt. Troy areas, ranging far and doing no formal testing, as the facets over a mostly stable base continue to only sluff, while the windloaded areas continue to be very weak and sensitive. Travel conditions are mostly good now in areas not too exposed to the NW to NE winds of the last week. Wind-exposed areas are either windblasted crust on the windward slopes or tender windslab on the lee slopes.

Temperatures continue to be cold and the only melting we saw was on the trees in the warm sun. The snow is becoming more sugary and faceted, and will function very effectively as a weak layer over the icy melt-freeze crust from last week whenever we get enough of a slab loaded on top of it.

Watch out for windloading and heavy new snowfall. Until then, stay out of windloaded areas and beware of the very steep rocky chutes where weak layers are most likely to be persisting.

Photos
The air temperature stayed cool today, with no melting of the snow even on sunny slopes, but the sun was warm enough to make the snow on the trees melt and drip onto the snow under them.
Icicles were forming on the trees as melting snow dripped from them. This requires a combination of warm sun to melt the snow and cold air to freeze the icicles.
Marc Scholten telemarks in the powder. Steeper southerly aspects were a bit crusty in places and the snow had settled to a thinner layer. The best snow was on aspects with little sun.
Marc Scholten finishes a turn in a flying cloud of sugary faceted powder. This loose, weak snow that has formed in the last few cold days lies over an icy melt-freeze crust from last week and is not bonded at all well to it. The next significant windloading or new snow is likely to form the slab that will produce an avalanche cycle.
The upper bowls of Mt Troy were tracked out to the point where they were not much worth climbing for.
Though we generally found stable snow today, a snowmachine recently attempting to climb a 45°+ route through the rocks and rolling back downslope managed to find a weak spot and trigger a small slab avalanche.

With their high horsepower, fast travel, ability to transfer tremendous shear force, and the deep trenches they dig into the snowpack, modern snowmachines make good instability locators. Virtually every terrain trap, avalanche path, and poor route choice on the upper part of Mt Troy had tracks in it. Riders were lucky that the snowpack has been very stable this week.

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