Pro Field Report

Basic Information

Observation Details

Observation Date:
February 23, 2021
Submitted:
February 23, 2021
Observer:
SAC - Scott Savage
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Hailey to 4th of July Ck: driving and glassing (many aspects and elevations, but all roadside)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced
No on snow observations for cracking and collapsing, so those observations are N/A.

Bottom Line

Strong winds past 24 hours moved a lot of snow at all elevations and are still moving snow in Sawtooth and Western Smoky zone at ridgelines. I saw a couple large, fresh avalanches and others that I'm not sure on the timing. I did not see widespread fresh wind slabs, but the wind added snow/weight to many middle elevation slopes and select upper elevation slopes. The wind event filled in or erased all signs of the past few days' ski tracks in exposed middle and upper elevation terrain.

Media/Attachments

Slab avalanche (unknown release date) in the W Fork Boulder Ck drainage, on the ridgeline south of Silver Peak in the Boulder Mtns.
Large drifts on aprons below steep chutes in the Boulder Mtns.
Small recent slide in Anderson Ck, cornice fall.
Slab avalanche on the SE face of Saviers Peak in the Smoky Mtns. Unknown release date, SE aspect near 10,200' elevation.
Wind dunes and ripples on east aspects at upper elevations on Saviers Peak in the Smoky Mtns.
Wind-affected snow surface at the middle-upper elevation transition in the Smiley Ck drainage, Smoky Mtns.
Active wind transport on McDonald Peak in the southern Sawtooth Mtns Tuesday afternoon. Note the shiny crusts on the SE aspect on the left of the photo.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Temperature:
teens F at pass level
Wind:
Strong , NW
New/Recent Snowfall:
4-8cm around Galena Summit, but wind made it hard to tell

Cloud cover: CLR in WRV through Boulders, PC in Smoky Mts and around Galena Summit, MC/OVC western Smokys and southern Sawtooths, obscured and snowing northern Sawtooths and northern White Clouds.
Strong NW winds moving snow in Sawtooths, mostly out of snow available for transport with current wind speeds and direction from Smiley Creek south.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Feb 23, 2021
(+/- 1 day) 		Westernhome Gulch
S 9650ft 		D2 U-Unknown O-Old Snow 2ft N-Natural
These 2 large slab avalanches released naturally during the strong NW wind event Monday or Tuesday in the Westernhome Gulch drainage (9650', S-SE).
Report
1 Feb 23, 2021
(+/- 1 day) 		Westernhome Gluch
SE 9650ft 		D2 U-Unknown O-Old Snow 3ft N-Natural
These 2 large slab avalanches released naturally during the strong NW wind event Monday or Tuesday in the Westernhome Gulch drainage (9650', S-SE).
Report
Westernhome Gulch
Westernhome Gluch

The Westernhome Gulch slides looked fresh, and the starting zones were likely loaded by this wind event. The crown depth, shape, and location indicate they probably failed on the 1/27 crust+FC layer that's been producing activity recently.

Snowpack Observations

No snowpack observations.

Avalanche Problems

The Westernhome Gulch slides fit the recent pattern of wind-affected, south-facing starting zones failing 2-4 ft deep, not surprising given the strong NW wind event over the past 24 hrs.
Upper elevations: I saw lots of wind-affected snow, dunes, and ripples but not much in the way of obvious fresh wind slabs. Guessing the wind blew too strong to form widespread slabs.
Middle elevations: All the tracks from this weekend around Galena Summit were blown in/erased/"ghosted" by the wind event and snow. Many middle elevation slopes were loaded by the wind event, although there appeared to be very few if any fresh middle elevation wind slabs.
Upper/middle elevation transition: Slopes over 35* in this elevation band would be the scariest place to be in my mind right now. We have well-developed weak layers and a healthy dose of wind-transported snow in the past 24 hrs, especially on SW-S-SE aspects where most of the recent activity occurred and the wind loading is most obvious.

Terrain Use

Driving and glassing to look at wind effects over a large area, so no terrain choices were made.