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Observation: Whitney Basin

Observation Date
2/19/2013
Observer Name
Ted Scroggin
Region
Uintas
Location Name or Route
Whitney Basin-Moffit Peak
Weather
Sky
Clear
Wind Direction
Southwest
Wind Speed
Strong
Weather Comments
Mostly clear conditions with very strong winds blowing snow around even in the lower elevations.
Snow Characteristics
Snow Surface Conditions
Dense Loose
Wind Crust
Melt-Freeze Crust
Snow Characteristics Comments
A big change in the snow conditions from yesterday, with today's strong winds getting into lots of areas. Only the most protected places escaped the winds. South aspects were crusted, while settled dense powder was still found on the shady aspects.
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Cracking
Poor Snowpack Structure
Red Flags Comments
Winds being the main issue today, with northwest through east facing slopes developing new and somewhat sensitive wind drifts. These would crack out around sleds and skis up to a foot deep. I stumbled across two fairly recent sled triggered slides from the weekend. One appears to be an isolated wind slab that did break into old snow at the ground. The other slide a couple of feet deep failed on the January facets on a steep 38 degree north facing slope, where the snow pack has been thin all season long.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
Fresh wind drifts were today's main issue, some of these were 12-16" deep mainly on north through east facing slopes.
Avalanche Problem #2
Problem
New Snow
Trend
Increasing Danger
Problem #2 Comments
Although isolated, the two sled triggered slides I observed still indicate the possibility of triggering an avalanche that breaks into old snow. I think the right combination of steep slope angle, thin snow pack and slope aspect are needed. With a forecasted storm this week, the hazard will likely rise and more of these types of slides could be possible.
Comments
A small pocket that was triggered this weekend on an east facing slope about 10,000'. It looks like it broke into old snow near the ground. This slope receives a lot of wind loading from southwest winds.
This was another triggered slide from a day or two ago. I estimated it to be 2'deepx50'widex100'vertical. It is on a northeast aspect, 10,000' in elevation, 38 degree slope on Moffit Peak. The slope has some rocks poking through and this was likely the trigger point. It did fail on the January facets and in some places broke to the ground. Second photo-not a big slide, but enough to slam a person into some mature evergreens. Third photo-in some places the slide did break to the ground. Fourth photo-compression and ECT scores were 20 and 21taps from the shoulder with Q1 shears.
Some of the weakest snow has been found in the mid-slope areas where the snow pack is thin.