Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
December 9, 2022
Submitted:
December 9, 2022
Observer:
NWAC Forecaster - Andy Harrington
Zone or Region:
West South
Location:
Paradise

Signs of Unstable Snow

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

Media/Attachments

This small test slope was wind-loaded and cracked, showing signs of failing.
Close up of the buried surface hoar grains at Mt Rainier. Note the large feathery appearance. 
All large column snowpack test failed and propagated on the lower surface hoar layer Friday (12/9).  [ECTP24]
Snow profile highlighting buried surface hoar at Paradise on Mt Rainier. As similar structure was found on all aspects. 
Shovel shear test highlighting the buried surface hoar layers
Shovel tilt test resulted in a clean break on a surface hoar layer.

Advanced Information

Weather Summary

New/Recent Snowfall:
~10" HN and probably another 1-2" fell during my time out

The day started with mostly cloudy skies and even a few sun breaks before transitioning to windy and snowy. Mostly S1

No new avalanches were observed, but I was able to get some cracking and blocks of snow to fail on a wind-loaded convexity.

Snowpack Observations

I spent most of the day digging and found buried surface hoar on all aspects in the Paradise vicinity. There were two layers of concern (12/4 and 12/8) that consistently showed up in almost any test you could throw at them. Shovel shear, shovel tilt, compression tests, and extended column tests (ECT) all produced results. The 12/4 propagated to the end of the column in every ECT I performed, regardless of aspect. The 12/8 would consistently fail but not propagate the width of the block, except in my northerly facing pit. I was consistently finding the 12/8 around 10 inches below the surface and the 12/4 around 20 inches below the surface. Despite being easy to find and the concerning test results, I did not see a single avalanche, shooting crack, or whumpf during my time out. Visibility was limited and I mainly stayed in the meadows around Alta Vista, however.

Other observations of note were settlement cones around trees and some snow transport during gustier periods of the day.

WordPress Lightbox