Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
February 20, 2022
Submitted:
February 20, 2022
Observer:
NWAC Forecaster - Lee Lazzara
Zone or Region:
West North
Location:
Mt. Herman (4200' > 5600' all aspects)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Heat triggered, very small loose snow avalanches on a south aspect of Mt Herman. With a higher and stronger sun in late winter, heat related instabilities are likely to occur shortly after the sun hit a slope. Photo: Lee Lazzara

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Wind:
Calm
New/Recent Snowfall:
30cm new over 2/19 crust - 40cm - some times as deep as 60cm - in wind loaded locations

Cloudy with sun breaks, felt warmer than Baker telemetry indicated. Sun is strong enough now to initiate heat related instabilities in new snow shortly after initial sun exposure.

A few small wind slabs high on the east aspect of Table likely triggered mid-storm on Friday (crowns, bed surface and debris all partially filled in). Small heat triggered loose snow avalanches and rollerballs, pinwheels observed on SE and S aspects NTL

Snowpack Observations

New snow is overall right side up F at the surface to 1F near 2/29 crust down 30cm in sheltered terrain. New snow appears well bonded to crust, minor sluffing in very steep terrain. No slab instabilities were noted with test slopes, hand pits, and other informal tests in wind sheltered terrain. Wind loaded slopes were observed to have more, but subtle, density breaks in new snow layers. Isolated but deep cracking in very steep terrain, generally SE-NE facing slopes just below ridgeline when transitioning from NTL to ATL. Large column test in a very wind loaded location (E @ 5600') produced ECTN's in new snow layers, CTM-SP down 62cm in slightly weaker snow below 2/19 crust. Tilt test, shears, produced easy results in new snow layers. No results around V-day crust.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
None Specified
WordPress Lightbox