Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
April 1, 2023
Submitted:
April 1, 2023
Observer:
NWAC Forecaster - Katie Warren
Zone or Region:
East Central
Location:
Thorp Creek (2300-5100ft; Primarily W and N aspects)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Small storm slab, 4" deep, that ran on the old snow surface. 4400ft on a steep road cut bank. Likely triggered by a tree bomb.
Shooting crack on a steep wind-loaded test slope.
Natural small storm slab that ran on a steep slope into a creek drainage. 4200ft
Where I left the snowmobile at 4000ft there was around 8" of new snow over a moist melt freeze crust.
At higher elevations in more exposed terrain, easy hand shears showed the slightly stiffer wind slab over softer storm snow.
Wind drifts around trees near the ridge.
The sun played its own April Fool's Joke on me, peeking out of the clouds only to quickly disappear again.
Wind textured surfaces along the ridge.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Moderate , NW
New/Recent Snowfall:
20-30cm HST

It was a classicly unsettled spring storm day. Periods of gusty winds and moderate snow, along with brief periods of full sun. There were small new cornices, wind-drifted snow, and plenty of ongoing wind transport throughout the day.

Two very small storm slabs ran naturally overnight. SS-R1-D1-I
Both were on steep (40+°) slopes and had minimal propagation.

Snowpack Observations

At the trailhead, there was just around 5cm of new wet snow, and until around 3000ft, some bare patches of the road just held the minimal new snow totals. Above 3000ft, snow totals increased significantly, and I found 20cm of storm snow over a 3cm moist melt-freeze crust at 4000ft.

I climbed low-angle slopes to a ridge at 5000ft. New snow seemed to have a favorable bond to the old snow surface. Although there was evidence of small natural avalanches, hand sheers and test slopes in sheltered terrain produced no notable signs of instability. Winds were actively drifting snow along the ridge, and fresh wind slabs were widespread. On lee slopes below the ridge, wind slabs would crack with a solid jump but were not particularly sensitive.

In the afternoon snow was becoming heavier below 4000ft and, I did get a small wet loose avalanche to slide on a steep road cutbank.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy