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Professional Observation

Basic Information

Observation Details

Observation Date:
February 4, 2020
Submitted:
February 4, 2020
Observer:
SAC - Savage, Stefan
Zone or Region:
Galena Summit and Eastern Mtns
Location:
glassing Hailey to Stanley

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced
Highway observations glassing terrain with binoculars. Cracking and collapsing information does not apply.

Bottom Line

The NE wind event caused extensive wind loading - and damage! - in the mountains from Croy Canyon/Hailey to the northern Sawtooths. Wind effects were most pronounced in the Boulder Mtns and southern Sawtooths. We observed significant natural avalanche activity in the Boulder Mtns. All activity was on generally west-facing slopes (thin snowpacks) and appeared to predominantly fail on persistent weak layers (likely facets/depth hoar) in the lower half of the snowpack, all in wind loaded areas. We did not see activity except in the Boulder Mtns, but we weren't able to see as much recently wind-loaded terrain (NW-W-SW-S) aspects in other mountain ranges. We could not see much in upper and middle elevations in the Pioneers, but we received reports of significant avalanches that occurred yesterday on west aspects in the Pioneer Mtns near Grays Peak.

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
single digits F
Wind:
Light , N

Increasing high clouds in Sawtooths by 1 PM. Variable N winds, gusty in favored locations.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Past 24 hours Eagle Creek Headwaters
SW 9600 		D2 U N-Natural Slide was over 500' wide, spanning W-SW-S aspects, failed in wind-loaded area well below ridgeline. It appeared to fail on a weak layer near the middle of the snowpack.
Feb 3rd natural avalanche in the headwaters of Eagle Creek: SW aspect, crown is more than 500' wide.
1 Past 24 hours Easley Peak area - east of the peak
W 10200 		D1.5 N-Natural Slide failed in wind-loaded area well below ridgeline. Blown in, likely happened early yesterday.
Feb 3rd natural avalanche near Easley Peak in the Boulder Mtns: W aspect near 10,200'.
1 Past 24 hours Gladiator Creek - towards Senate Ck
SW 10100 		D2 N-Natural Slide noted in public observation today. Narrow slide (about 50'), failed at ridgeline on deeper layers in snowpack. W/SW aspect. First spotted yesterday afternoon.
Feb 3rd natural avalanche above Gladiator Ck, Boulder Mtns. This slide failed on a W-SW facing slope near 10,000' in elevation.
1 Past 24 hours Cherry Creek - off Spring Ck/Cherry Ck ridge
W 9900 		D2 N-Natural Slide was 150-200' wide, failed on persistent layers in the lower half of the snowpack.
Natural avalanche on Feb 3rd in the Cherry Ck drainage, Boulder Mtns. This slide was 150-200' wide, failed on persistent layers in the lower half of the snowpack, and released on a W aspect near 9900'.
1 Past 48 hours Williams Peak - Sawtooths
S near summit 		D1.5 N-Natural Hard to tell whether a wind slab or loose snow avalanche, size D1.5-2. Occurred on S-SE aspects in wind-loaded terrain within 300' vertical of the summit. Unsure on timing, but it appeared to be recent. None
2 Today Williams Peak area - Meadow Creek bowl
SE 8500 		D1 L I-New/Old Interface N-Natural Small sun-induced loose snow slides on E-SE aspects in rocky, wind-loaded, alpine terrain in Meadow Creek Bowl. None

Terrain Use

Driving obs, no terrain open or closed.

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