Professional Observation

Basic Information

Observation Date:

December 22, 2021

Submitted:

December 22, 2021

Observer:

WCMAC - Jeff Carty

Zone or Region:

Rattlesnake

Location:

Around Point 6

Recent Avalanches?

Yes

Cracking?

Isolated

Collapsing?

None Experienced

One small, (

Stability Rating:

Good

Confidence in Rating:

Moderate

Stability Trend:

Worsening

Advanced Information

Cloud Cover:

Mostly Cloudy

Temperature:

25º F (-4ºC)

Wind:

Light , SW

Mild wind all day, no snow transport observed.
No precipitation during the day.

#	Date	Location	Size	Type	Bed Sfc	Depth	Trigger	Comments	Photo
1	Today	Jenny Bowl E 7800'	D1	HS	I-New/Old Interface	6"	N-Natural u-Unintentional	This was a very small slide caused by a falling tree. It shows there are still small pockets of reactive wind slab.

We got surprised by reactive basal facets under 150cm of snow. This is in contrast to the well-rounded snowpack found elsewhere in the forecast area. The pit was dug near the ridgeline at 7800 feet, in an exposed location. Past scouring and consistent winds likely contributed to facet development. We had an extended column test propagate on the 22 taps 39 inches down (ECTP22 down 100cm). The block slide with force into the pit. However, these reactive facets seem to be isolated to exposed ridges and shaded aspects. A propagation saw test (PST) done adjacent to this pit showed low propagation likelihood, and an ECT 200 feet downslope had no failure. It is good to note that facets exist in isolated areas in the Rattlesnake. Throughout our tour, we found shallow spots around buried rocks where facets have grown. Triggering a slide in this layer is unlikely due to limited distribution, but a slight possibility exists. It is best to avoid these areas as you tour in the Rattlesnake. Most aspects had wind buffed snow, and the snowpack has stiffened up considerably from two days ago.
The freezing level was around 6000 feet, with snow getting progressively heavier below this.