February 19

Porter Fork-main Porter-east fork-main Porter

Elevations, slope angles and aspects

6200-9500', angles over 35°, north' east and west facing aspects.

Snow conditions

2" new over the 8-10" of recent snow. New snow was of a medium density.

Recent snow is right side up with good bonding. Some surface sluffing was observed on very steep slopes.

Lower elevations and off aspects have several thin crusts within the recent snow.

Wet activity(rollers) was observed at lower elevations.

Avalanche activity

Slowshoed up for a look at two slides in the east branch of main Porter Fork.

ne-slide

North east facing just west of the pass, 9400'

ne-crown

Slide was about 50' running several hundred vertical feet. 4-14" deep, slope angle, well over 35°.

profile

Northwest facing, mid slope fracture, 9000'.

Backside of Raymond "piece of pie". Angle over 35°.

seconds

Slide initiated in a steep little catch basin and spread across the open slope.

Fish eye view looking down.

fish-eye

Fracture was 150' or so wide, 2-12" deep, a little deeper on the flanks, running several hundred vertical feet, through trees.

Weather

Mostly cloudy skies, moderate temperatures, light wind from the northwest. Snow flurries, all day.

Snow pit

Crown profiles in several locations along the fractures of both slides.

Weak layer was surface hoar.

The northeast facing slide had an obvious up right surface hoar layer(see profile photo).

There was another weak layer down about 2-4", interface of different snowy periods.

Northwest facing wasn't so obvious, with hoars flattened.

Easy shears, Q1-Q2, all locations. Q2 rating given to shears lacking the "knock the wind outta ya" energy with failure.

Evaluation

Found the rare and elusive hoar frost to be not so in upper Porter Fork.

It's hiding under the recent snow in sheltered terrain, primarily below about 9500' and above 8000'.

Instability would be localized in mid elevation terrain, steep slopes, likely drifted, sheltered.

Easy shears suggest continued active instabilities from this layering.

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February 19 journal

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