Avalanche: Chugach State Park

Location: North Bowl, South Fork ER

Date:
Observer:
Route & General Observations

APU Snow Science class toured to Hunter Pass and North Bowl to make observations about the Valentine Week’s storms impact on the Front Range. This was quite a popular spot today with Seward highway & Hatcher Pass avalanche closures.

Avalanche Details
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Trigger NaturalRemote Trigger Unknown
Avalanche Type Hard SlabAspect Unknown
ElevationunknownSlope Angle 35deg
Crown Depth3ftWidth 200ft
Vertical Run 800ft  
Avalanche Details

Several natural avalanches had run on both sides of the valley within the last 24 (-48?) hours. Most impressive ones were on two
E facing gullies of Rendezvous ridge that had run all the way to the treeline. Also notable wind slab release on NW ridge up Harp Mountain (R1-D1.5) that ran quite far down the bowl.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

Skies obscured most of the day, broken by ~2pm.
Temps below freezing the whole day.
Winds variable, but mostly light w gust of moderate from south.
Precip: very light snow on and off with one bout of graupel. Not much accumulation during the day.

Snow surface

We were pleasantly suprised by the colder snow surface than we were expecting.
~5-10cm of soft new snow on the surface depending on location.
Above and near treeline varied surface conditions included glare raincrust, soft windpacked snow and 20cm high sastrugi.

Snowpack

We were expecting more reactive new/old snow interface, especially with wind slab, and were curious about lower snowpack persistent layers, but our test results showed fair stability. We dug four pits at Hunter Pass (N aspect, 2750', 22-25deg slope) and none of the test results were super reactive. HS varied 110-125 with one pit dug on super loaded spot w HS 235 cm. There was 40cm slab, but the weak layer (10cm of facets ~80cm down) was not failing nor propagating.

Photos & Video
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