Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Matt Primomo
Observation Date:
January 30, 2021
Submitted:
January 30, 2021
Zone or Region:
East Central
Activity:
Location:
Icicle Creek

Signs of Unstable Snow

Did you see shooting cracks? 
No
Did you experience collapsing or whumpfing? 
Yes, Isolated

Observations

Overcast day with valley fog, some riming. Light wind, no blowing snow observed up to high point at 6,500ft. Traveled on N to NE aspects.

Found buried surface hoar 5-8mm at 1/24 interface (just above crust) on NE at 4000ft. Hand shears revealed this layer easily.

At ~4,200ft an ECT failed upon isolation, on faceted melt forms underneath the crust down 40cm.

Watched a fellow backcountry traveler perform an ECT a few hundred feet above that, with no results on the layer of concern. The crust was down ~60cm here, under thicker snow due to some previous wind drifting.

We observed only very small, underfoot breaking of the crust most of the day, until skiing down a more wind exposed feature. A 20 degree north facing slope at 5,900ft had cross drifted slabs from previous east winds, and each skier noticed large whumphs as they skiied over some of these hidden slabs.

Media

Quick profile at site of some large collapses, where crust was failing on very weak faceted melt forms below.
WordPress Lightbox