Location: Crested Butte Area
Date of Observation: 02/11/2019
Name: Zach Kinler and Eric Murrow
Subject: Long Lake activity
Aspect: North East, East
No new avalanches observed.
Weather: Blustery and cold @ 11:00 with light to moderate winds at valley floor,16F, Broken skies. After frontal passage, skies cleared and temps warmed a bit with pleasant conditions in the trees.
Snowpack: Visited a D2 avalanche that failed around the 1/16-1/18 loading event. Bed surface was filled in with ~40 cm of F hard snow. HS near crown 130cm. This avalanche failed in an open East facing slope below tree line and propagated into sparse aspens and pines. The crown was ~ 60cm deep across the slope and bed surface was a 1.5cm crust 33 cm above the ground that likely formed after a warm dry spell in mid December left a crust on top of weak snow from Nov and early Dec . Below the crust was 3 mm F-4F- Depth Hoar/Faceted Crystals.
In the shallower zones with HS below 150 cm such as this area, the snowpack has old, well developed faceted snow, 4f hard, at the ground from Thanksgiving storms and a cohesive 1f slab resting above. Mid-January (1/15) weak layer and 2/2 interface will be players during upcoming loading event as well as basal layers if loading comes slow and steady. Test results were ECTN on 2/2 and ECTX.
Old bed surfaces from January avalanche cycles will come to life relatively early in the next loading event. Snow from MLK week snow and 2/2-2/7 snow that filled in this bed surface is losing cohesion and faceting – will not accept much of a load before failing again.