Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
December 28, 2021
Submitted:
December 28, 2021
Observer:
NWAC Forecaster - Andrew Kiefer
Zone or Region:
Mt Hood
Location:
Pea Gravel Ridge (4600-6200ft, All Aspects)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

On December 23, a very large natural avalanche (D4) released from high on the Newton Clark Glacier depositing debris down to 5400ft in Clark Canyon.
Obvious wind loading on Pea Gravel Ridge. The west-facing windward aspect is scoured with exposed rock, and the east-facing leeward aspect is fat and loaded. A few inches of new low-density snow masks previous wind deposits in many other areas making them not so obvious to identify.
Storm snow since 12/21 is settling, gaining strength, and well bonded to the solstice crust.
The storm snow since 12/21 is settling and stabilizing in wind-sheltered areas. There were no notable results in snowpack tests at this pit site in Newton Creek (E, 5200ft). Storm snow was right-side-up and well bonded to the solstice crust.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Temperature:
15-20°F
Wind:
Light , W
New/Recent Snowfall:
4-6in past 24hrs, 76in (6ft+) since 12/21,

High temps hit the low 20's F and winds were calm to light out of the west. Skies were mostly obscured with a few partial clearings giving way to brief views of the upper mountain. Periods of light snowfall with 1-2in of new snow between 9am-3pm.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Dec 23, 2021
() 		Mt Hood, Newton Clark Headwall
E ft 		D4 HS-Hard Slab O-Old Snow N-Natural
On December 23, a very large natural avalanche (D4) released from high on the Newton Clark Glacier depositing debris down to 5400ft in Clark Canyon.
Mt Hood Meadows Ski Patrol
Mt Hood Meadows Ski Patrol
Mt Hood Meadows Ski Patrol
Report
Mt Hood, Newton Clark Headwall

Debris from a very large natural avalanche (D4) that ran on 12/23 filled Clark Canyon down to 5400ft. The debris was 30-40ft deep in places. The crown of the avalanche was not observed.

Snowpack Observations

76in (6ft+) of storm snow since 12/21 has settled to 48in, and is right-side-up (F-4F-1F-P) and well bonded to the solstice crust (P). The height of snow was 100in in a test profile in Newton Canyon (5200ft, NE), and there were no concerning results in tests - fractures did not propagate and were resistant planar or irregular.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Dry Loose
Isolated
Specific
Widespread
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
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