Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Enji Cooper
Observation Date:
December 27, 2020
Submitted:
December 28, 2020
Zone or Region:
West South
Activity:
XC Skiing/Snowshoeing
Location:
Mt. St. Helens - Worm Flows Route

Observed Avalanches

Did you observe any avalanches? 
Yes
Avalanche Type:
Wet Loose
Size:
Size 1: Relatively harmless to people
Elevation:
Near treeline/above treeline
Aspect:
SE
Comments:
Observed wet loose avalanches on multiple aspects (E, W) on south climbing route (between 4.2k' and 4.6k') along several gullies bordering the ridge in the morning (before 10:00 PDT). All debris was small (D0.5~D1), but hinted at minor instability low early in the morning.
Photo:

Signs of Unstable Snow

Did you see shooting cracks? 
Yes, Isolated
Did you experience collapsing or whumpfing? 
No

Observations

Please see observations above.

I didn't dig a snow pit or do any hand shear tests as the ridges we were traveling on were "low risk" due to how wind scoured they were.

Wandering off the ridge (booting it, both with and without crampons) resulted in more deep snowpack though (barely over 1'), which forced me back to less deep snowpack for stability and safety reasons.

Several folks attempted to glissade down sections between 5k'~7k' and were met with non-ideal glissade conditions due to temperature/firmness of snowpack.

Media

Around 6k', looking ESE in the morning (12:00 PDT)
Around 5.7k', looking ESE in the afternoon (16:00 PDT)
Wind fetch/rime ice being blown off ridge around 5.7k' (16:08 PDT)

Advanced Observations

Observed Avalanche Problem #1: 
Wet Loose
Comments: 
D0.5 as noted above.
Observed Avalanche Problem #2: 
Wind Slab
Comments: 
Between 4.6k' and 6.5k', I observed drier conditions resembling wind fetch. My partner and I were kicking down small carbs (3cm~5cm diameter) with snowshoes and crampons.

Up higher (around 6.7k'~7.7k'), I observed isolated wind slab conditions along the ridge, thus I purposely stuck to lower coverage/elevation slopes with my crampons to mitigate potential risk from triggering a slab. That being said, several skiers rode the ridge (both from the summit and below the summit) without triggering any avalanches (just kicking down carbs).

Afternoon/evening winds were around 20+mph, blowing rime ice S down the crater from the mountain.

I suspect that much of the risk on Mt. St. Helens is in the gullies and less disturbed snowpack on opposing ridges.
Observed Avalanche Problem #3: 
Cornice
Comments: 
Cornices were starting to form on opposing ridges to climber's route in the morning. The overhangs appeared to be approximately 3".
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