Observation: White Rock Hollow

Observation Date
2/19/2013
Observer Name
Weed, McAvoy
Region
Logan
Location Name or Route
White Rock/ Charlies Ridge
Weather
Sky
Broken
Wind Direction
South
Wind Speed
Moderate
Weather Comments
Mild and a bit windy in exposed areas.
Snow Characteristics
New Snow Depth
2"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Melt-Freeze Crust
Snow Characteristics Comments

We found nice fast shallow powder (re-crystallized) on north, northwest and northeast facing slopes.

Red Flags
Red Flags
Wind Loading
Red Flags Comments
Only real red flag was on-going wind drifting. The snow was beeing tranported by the stronger winds, building dune-like drifts. The snow is scoured off exposed south facing fetch areas and deposited in stiff, sometimes broad drifts where the winds are slowed due to terrain. We avoided drifted slopes and steep areas on the lee (northeast facing) side of the ridge, and did trigger any cracking or collapsing while traveling in lower angled north east and west facing terrain. Areas with poor snow structure appeared limmited to shady areas with generally shallow snow cover.
Avalanche Problem #1
Problem
Persistent Weak Layer
Problem #1 Comments

We didn't really test any obvious drifts, and did not see any sign of natural activity. But, we noted significant surface drifting. I am concerned about drifted slopes where weak near surface facets formed during cold high pressure conditions in early February and only a couple inches accumulated incrementally since. Wind slabs developing on potentially persistent weak layers may remain sensitive to human triggering for a while, and hard slabs often allow you to get well out on them before releasing.. Because of these factors; stiffening and building on potential weak layers, the wind slabs are getting more unmanageable and dangerous.

Video