January 31

Yellow Jacket, Alexander Basin

Elevations, slope angles and aspects

6200-9600', angles over 35°, north, east and west facing aspects.

Snow conditions

There was a surface melt freeze crust from the trail head to around 8k. Porter Fork road had a number of ice patches.

Off aspects above were also crusted but, not as thick. Sheltered lower elevation exit only had a zipper crust

Settled powder was found in mid and upper elevation sheltered terrain.

Upper Alexander Basin was wind hammered with extensive debris piles.

echute

Ski penetration was 0-4". Boot penetration was a foot or so.

No cracking or collapsing.

Weather

Overcast to partly cloudy skies, light wind and moderate temperatures, inverted.

Snow pit

Left side show the layering found with 18" recent snow over wind layer over very dense snow from the January 20 rain-snow event.

yellow-jacket-snowpit

Right side shows the shovel shear in the first column on facets under the December 28 rain crust.

The second column failed while I was cutting out the back with a snow saw.

Will do a profile when time allows.

Evaluation

Mostly stable snow was found in the area. No avalanches in Yellow Jacket, widespread in Alexander Basin on all aspects, both upper and mid elevations.

Stout bridging over old faceted snow suggests increased difficulty of stability evaluation.

Larger trigger or hitting the "sweet spot" may produce avalanche in areas that haven't.

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