Observation: Turnagain

Pete’s North
Field Observations
January 17, 2013

No Recent Avalanches (good visibility)
No Collapsing/Whoompfing
Very small shooting cracks above treeline (~6ft)

Surface Observations
Variable with elevation.
Supportable crust, 1-3″ thick from 1000-1800′, with 2″ light density new snow on
top.
Firm snow from 1800-2800, with 0-2″ light density new snow on top
Ridgetop winds were picking up in the late afternoon, after 3pm, predominantly
from the West. Snow was being transported onto East facing high elevation
starting zones.
Small isolated pockets of very shallow new wind slab were found on W and SW
aspects above treeline.

Pit Results @ 2400′ W aspect, 30 degree slope
ECTP 30, CT 28 Q1
High Strength: strength test scores ranged from 28-30
High Propagation Potential: when columns broke, things propagated readily
Poor Structure: fist hardness 3mm facets make up the bottom 10cm of the snowpack
in this location.

Pit results synopsis and how it relates to likelihood and consequences of
avalanches: It is getting very difficult to initiate a fracture in many areas.
This is due to a very thick slab that is very strong on its own. Once a
fracture, or crack occurs, the ability for an avalanche to become large is high.
The general structure of the snowpack is poor, in that there is a weak layer
that is very loose at the bottom. To put it in very simple terms: the
likelihood of triggering an avalanche is very low, but the consequences are very
high.

In order for an avalanche to be initiated, a person would have to hit a very
thin spot in the slab. Knowing with certainty where these spots are and aren’t
is difficult. Warming temps and new loading might encourage fracturing as well.

The facets that were formed beginning in October are still large, dry and have a
lot of pore space between grains. This layer is intact; we will continue
tracking this layer over time. While it may be impervious to human triggers for
now, it is still there, lurking below.