Avalanche: Hatcher Pass

Location: Twin Lakes

Date:
Observer:
Claire Bicknell
Route & General Observations

Toured up to the Twin Lakes Valley to search for wind slabs, and test the stability of faceted snow on top of the Feb 26th crust. The southerly aspects at 1900’ had a thick sun crust, and the elevations past 2500’ were covered in impressive sastrugi.

Contact, Location & General Observations
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Forecaster Comments

Small natural wind slabs could have been 2-3 days old.

Avalanche Details
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Trigger NaturalRemote Trigger Unknown
Avalanche Type Hard SlabAspect West
Elevation 3400ftSlope Angleunknown
Crown DepthunknownWidthunknown
Vertical Rununknown  
Avalanche Details

Several small wind slabs from past 24-48 hrs had naturally released in the gully coming up the valley, along with another small wind slab on the west facing slope near the mouth of the valley ~3400’.

Red Flags
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Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

Several large whumphs observed while traveling near a wind loaded feature.
One crack observed at ~2600’

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

More wind effect than expected gives evidence for extreme winds overnight. Marmot station may have under reported wind speeds.
Calm to light winds during the day
Few clouds for the duration of the tour

Snow surface

Sun crust on southerly aspects.
Wind crust, and sustrugi on all observed aspects in the alpine

Snowpack

HS 230cm @2500’ SSW 13° Slope
ECTP30 47cm down- Failed by surface wind slab falling on facet sun crust.

HS 260CM @3300’ SW
ECTN
The Feb 26th melt freeze crust was observed but facets were not observed above the crust.

Photos & Video
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First pit marking crust ECT failed on @47cm down  

Tiny diurnal facets above the sun crust  

Debris from gully and nearby slope  

More debris down gully  

Older debris under rollover  

Location
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