Observation: DB Bowl Area

Observation Date
2/13/2013
Observer Name
Weed
Region
Logan
Location Name or Route
Sunset Boulevard
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
Winds gusted into strong catagory from time to time and skies obscurred above cloud bottoms at around 8000'. High RH and wind chill made for a pretty chilly day.
Snow Characteristics
New Snow Depth
1"
New Snow Density
Medium
Snow Surface Conditions
Powder
Snow Characteristics Comments

We found very nice smooth and fast shallow powder conditions. A bit of riming action going on, and rime blowing out of trees made it seem like a blizzard at times.

Red Flags
Red Flags
Wind Loading
Cracking
Poor Snowpack Structure
Red Flags Comments
We caused some locallized cracking on the Jan/Feb interface, 1-30 rime-crust capping thin layer with recently developed near surface facets and graupel, also some SH at this interface. Some shallow areas (<2') had very weak, well developed and dry 3mm+ facets under a few inches of fresher snow.
Avalanche Problem #1
Problem
Persistent Weak Layer
Problem #1 Comments

Wind slabs developing and likely an issue in and around terrain features and on the lee side of major ridges.. Stiffened and recently built-out cornices also something to be wary of along the ridges.

Avalanche Problem #2
Problem
New Snow
Problem #2 Comments

I noticed a widespread shallowly buried persistent weak layer at the Jan/Feb interface. Main concern here are sugary faceted grains formed near the surface during the cold early February high pressure system, but a capping rime-crust, graupel and surface hoar all add to the mix... The problem with spacial variability comes when you find constants, or less variation. Weak layers with the same properties widespread across a slope probably means avalanches will be more likely when a slab matures.

The existing snow structure is not very good either, with a currently dormant weak layer from early January consisting of fist-hard faceted snow.

Comments

Here are a couple examples of the localized cracking we caused. The cracks, up to around 6" deep were failing on a sugary weak layer at the Jan/Feb interface.... Developing wind slabs are likely to fail on the same layer.