Avalanche: Hatcher Pass

Location: Marmot

Date:

November 30, 2021 8:08pm

Observer:

Barker Kayes Forecaster

Route & General Observations

We toured up Marmot to see what winds from past 24hrs have done. We found small reactive wind slabs, 4 to 12″ thick, on SW thru NW aspects at upper elevation.

Avalanche Details

If this is an avalanche observation, click yes below and fill in the form as best as you can. If people were involved, please provide details.

Trigger	Skier	Remote Trigger	No
Avalanche Type	Hard Slab	Aspect	West Northwest
Elevation	4200ft	Slope Angle	32deg
Crown Depth	4in	Width	30ft
Vertical Run	40ft

Avalanche Details

We triggered two small wind slabs while stepping from ridge line on to the west face of Marmot. Both of these avalanches failed on bed-surfaces that were 4F to Pencil hard. The combination of new wind slab and firm bed surface is isolated and hard to find.

Red Flags

Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.

Obvious signs of instability

Recent Avalanches?	Yes
Collapsing (Whumphing)?	No
Cracking (Shooting cracks)?	Yes

Observer Comments

Recent winds and lots of snow available for transport.
Any place along the ridge where snow was 1F or harder would produce shooting cracks up to 30ft away.

Weather & Snow Characteristics

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

Weather

The weather felt warm compared to the recent sub zero temperatures.
19degF at 10am at 4500'
The sky was overcast to obscured through out the day. While touring we had trace amounts of snow fall.
Winds East 8mph, gusting 12 mph during our tour.

Of particular note: During 11/29-30 Marmot recorded winds SE to E to ENE to E to NE 10mph, gusting 15-20mph for over 30 hours. The wind slabs we observed today looked like the wind must have blown/gusted stronger and longer than recorded on the Marmot Wx Station to form these 1F wind slabs.

Snow surface

Snow surface and the total height of snowpack were variable while we toured. For most of the tour the snow pack was 40-50cm (15-20in) deep. At ridge tops the snowpack was less than an inch deep in places, with rocks and grass easily visible. On leeward aspects the snowpack was up to 185cm (6 ft) deep in isolated locations. Surfaces conditions vary by aspect and elevation. For most of our tour we observed soft, fist hard faceted snow at the surface. As we approached ridge-lines the snowpack became wind effected and was 1F hard in places. New wind slabs were isolated to ridges, just below ridges, on SW to NW aspects at upper elevation.

Snowpack

We dug a quick pit after we noticed shooting cracks and a small avalanche along the ridge line. 1F wind slabs failed on old sugary facets that were 1mm in size. We observed that avalanches were occurring in areas where a firm bed surface was present.

Photos & Video

Please upload photos below. Maximum of 5 megabytes per image. Click here for help on resizing images. If you are having trouble uploading please email images separately to staff.