Avalanche on Cameahwait

Location Name: BNSF Avalanche Safety - JFS Canyon Observation date: Thursday, March 11, 2021 - 17:15	Is this an Avalanche Observation: Yes

Observation made by: Public

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Quick Observation

Climbed into the upper starting zone of an avalanche path known as Second Slide to a high point at about 5700’ elevation.
Objectives were to investigate the avalanche that ran in this path on the night of Feb. 21st. Also, wanted to observe snow surface conditions and look for any recent avalanche activity in this vicinity and the surrounding terrain.

No crown for the avalanche in Second Slide could be found on the morning after it ran (Feb. 22nd) and could not find any remnants of one today either. However, by following signs of vegetation damage and debris piled on the uphill sides of trees, it was determined that this avalanche initiated in the bowl at the very top of the path and just below the prominent rock outcrop situated above the slope. This avalanche was a destructive size 2 of 5 that ran about 1200 vertical feet, terminating at the rail grade.
No recent avalanche activity was observed while on the ski tour.
From the Hwy, noticed some recent cornice fall in Shed 7 West and most notably a fresh crown on the SE face of Cameahwait (outside the Program Area). The Cameahwait slide looked about D2.5 size and possibly cornice fall triggered (photo). Also note glide crack to left of the crown. More details under Avalanche tab.

Sunny aspects had softened by the time I was on them in late morning. Shady aspects held breakable crust.
No signs of instability during the tour, no cracking, collapsing, or rollerball activity.

Mostly clear skies with no precipitation all day. Light westerly winds on the Canyon floor and moderate west-southwest winds above 5000’ elevation.
Daytime highs reached the 40s °F on the Canyon floor and just below freezing °F at elevations above 6000’.

Snowpack, Avalanche, Weather Images:

Avalanche Details

Avalanche Details:

Date and Time of Avalanche:

Thursday, March 11, 2021 - 12:15

Number of avalanches:

Avalanche Type:

Hard Slab

Failure Plane/Weak Layer:

Old snow

More information or comments about the avalanche:

Uncertain on details: Maybe cornice fall trigger? Crown dimensions and date/time of occurence are estimates. Guessing it was a hard slab failing on an older layer weak layer (perhaps mid-Jan PWL).

Trigger

Trigger:

natural

Trigger Modifier:

Cornice Fall Triggered

Terrain

Aspect:

Southeast

Starting Elevation:

7700

Size

Destructive Size:

D2.5

Relative Size:

R2 Small

Crown Height:

6 ft

Avalanche Length (Vertical Run):

1000ft.

Avalanche Width (Average width):

300ft.

Avalanche Location:

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