Pro Field Report

Basic Information

Observation Details

Observation Date:
February 20, 2021
Submitted:
February 20, 2021
Observer:
SAC - Lundy, VandenBos
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Beaver Creek (8000-9400', SE-E-NE-N)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced
The avalanche on Parks Peak looks to have occurred within the past 48 hours.

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
Moderate
Stability Trend: 
Steady

Bottom Line

We found the same layer buried 3' deep that was the culprit behind yesterday's accident in Smiley Creek, and observed a natural avalanche (maybe two) that likely released on this layer. Snowpack tests show that triggering this layer isn't likely, but certainly possible in steep, wind-loaded terrain. Gusty NW winds were continuing to load leeward aspects.

Media/Attachments

The Sawtooths received nearly constant low density snowfall over the past 9 days, which produced widespread loose snow avalanches (sluffs).
https://www.instagram.com/p/CLiQTQ9lpzU/

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Wind:
Light , NW

Skies were overall sunnier than forecast - they began FEW but eventually increased to BKN by afternoon. Late afternoon produced a few blizzardy squalls. Winds were generally light but regularly gusting to moderate and moving moderate amounts of snow. Temps remained cool to cold, especially in the shade, but the sun this morning was sufficient to but a soft crust on SE aspects.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Feb 18, 2021
(+/- 1 day) 		Parks Peak
SE 10200ft 		D2 N-Natural
This large avalanche on Parks Peak appears to have released within the past day or two. 10,200', SE
Report
1 Feb 17, 2021
(+/- 3 days) 		Beaver Creek
S 9300ft 		D2 O-Old Snow 3.5ft N-Natural
This large avalanche released several days ago in the Beaver Creek drainage near Smiley Creek. It broke over 120' wide in very steep, wind-loaded terrain. The depth and aspect (S) of the slide are consistent with a crust/facet layer buried about 3' deep. This same layer was responsible for a fatal avalanche in the Smiley Creek drainage on February 19th. 9300', S.
This large avalanche released several days ago in the Beaver Creek drainage near Smiley Creek. It broke over 120' wide in very steep, wind-loaded terrain. The depth and aspect (S) of the slide are consistent with a crust/facet layer buried about 3' deep. This same layer was responsible for a fatal avalanche in the Smiley Creek drainage on February 19th. 9300', S.
Report
Parks Peak
Beaver Creek

Glassed the Sawtooths with good light this morning, and saw surprisingly little slab avalanche activity. Loose snow avalanches were widespread, but nearly all were D1 in size - see photo.

Snowpack Observations

The morning sun moistened the top 5cm or so (at least on SE), and had already turned to a soft crust by mid afternoon. HS at mid to upper elevations averaged from 180-230cm. 12/11 was probed at around 170-180cm down.

@N, 9200': HS 230cm. No discernible weak layers in top 120cm except old wind layer from early Feb. ECTX.

@SE, 9300', 35*: HS 180-190cm. 1/27 facet/crust layer down 1m, slab ranged from F to P at base. Produced ECTP x3 on nonstandard loading steps (see video). 2/11 down 70cm gave ECTP30.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 100cm
Weak Layer(s): Jan 27, 2021 (FCsf)
Comments: Rose indicates observed terrain. ECTPs with nonstandard taps, older natural avalanche.

We observed active wind loading and got some isolated cracking in small drifts, but you would have needed to be in bigger and more exposed terrain to have encountered a wind slab problem.

Terrain Use

We avoided consequential slopes over 35 degrees.