Avalanche activity - Matterhorn area

Horse Creek - Matterhorn area
Submission Info
Sunday, March 24, 2019 - 2:30pm
Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
38° 6' 27.7056" N, 119° 22' 28.92" W
Snowpit Observations
More detailed information about the snowpack: 

Toured up Horse Creek drainage out of Twin Lakes to take advantage of the sunshine and check on new wind slabs.  Left the car at 9:45 under blue skies, calm winds, but a light haze throughout the area.  The lower north facing treed slopes from 7200-8400' were quite firm with virtually no ski penetration late in the morning.  No signs of any new snow until ~8500', and then just barely a trace.  Winds also were moderate down canyon at this elevation, blowing snow and covering up the shallow skin track in places from skiers who made it out earlier than we did today this morning.  We came across our first sign of recent instability on an north easterly facing rib at ~9200' that developed a small cornice that failed and triggered a small windslab likely early this morning or last night (see attached photo - R1-D0.5).  We ran into a group heading out of horsecreek who had spent an unpleasant night camped at 10,000' who reported 50mph winds most of the night, and new snowfall the previous day (unclear how much).  They decided to abort their mission to explore higher grounds today due to concern over fresh wind slabs.  We ran into another party later who skied down the west couloir of the Matterhorn and triggered a R2-D1.5 wind slab near the top couloir, luckily without anyone being caught.  Click here for details of that report and photos.  We dug many handpits, and several test pits along the way to the basin below the matterhorn in areas of suspect wind deposit, which all failed inconsistently, some with moderate force on deeper layers, some with light force on very shallow surface layers, some roughly, some cleanly.  It was still hard to tell exactly how much new snow actually fell yesterday as just about everywhere was either wind stripped or deposited, but our best guess would be not more than a few inches at higher elevations.  We found several isolated areas of shooting crack going perhaps a foot or two, and skiing down below treeline at 9400', we triggered a small 3-5" wind slab that propogated about 20' on a steeper convex NW facing sidewall of a gully feature.  We also saw a handfull of recent wet-loose slides in the distance on ESE facing slopes above 10,000', all originating from rock bands (see attached photos).  The lower elevation north facing treed slopes that were very firm in the morning had slight surface softening by the late afternoon, but only superficial (likely due to the clouds developing in the afternoon leading to the warming). 

Snowpack photos: 
Wet point releases from rock bands on ESE facing slopes
Weather Observations
More detailed information about the weather: 

Morning started with blue skies, but light haze.  Calm winds at low elevations, but mid and upper elevations had moderate SW winds until early afternoon, then died off substantially.  Overcast skies developed later in the afternoon.  

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