Storm obs from Slate

CBAC2020-21 Observations

Date of Observation: 12/29/2020
Name: Zach Guy


Zone: Northwest Mountains
Location: Slate River drainage
Aspect: North East, East
Elevation: 9,000 to 11,200 ft

Avalanches: Decent storm slab cycle last night from Happy to Climax to Schuylkill Ridge along with a few persistent slab avalanches
Happy Chutes: Lots of small slabs and sluffs, mostly D1. A D2 persistent slab
Climax: Debris through several of the chokes, looked like more shallow storm snow instabilities but light was flat, probably D1.5 to D2.
Schuylkill: Numerous storm slabs about a foot deep that ran near to the bench, D1.5 to D2. Two small persistent slabs on lower rollers that either ran last night or today. We remotely triggered two small persistent slabs on small terrain features, about 3 feet thick.
Wash Gulch: Plow triggered persistent slab, D2.
Weather: Light snowfall in the morning. Light winds. About an inch of accumulation. Overcast in the Upper Slate, broken skies near town.
Snowpack: Numerous large collapses in open slopes on low angled terrain and in small clearings in steeper trees. Storm snow is about 12″ to 15″ below treeline and 18″ near treeline, fist hard. Persistent slab structure is about 3 feet thick below treeline (Fist down to 4Finger). Cracking at or near the storm interface, especially as we gained elevation. We tested for “repeat persistent slab structure” in terrain that slid earlier this month. The structure was not reactive in pits, but there is still a lingering persistent weak layer near the ground, just denser and smaller with less of a slab than a pristine snowpack that hasn’t slid.