Large Natural Avalanche, Mt Baldy

Location: Paradise Divide Area
Date of Observation: 11/05/2018
Name: Evan Ross, Eric Murrow

Subject: Large Natural Avalanche, Mt Baldy
Aspect: North East
Elevation: 10,200-11,600

Avalanches:

Observed one good natural slab that ran about 2,000 feet which likely failed during Sunday night, 11/4. The slab didn’t necessarily look that large, but the avalanche path holds a steep enough slope angle that allowed the debris to keep running and accumulating snow along the way. This avalanche probably started as a wind slab or cornice fall at ridgline around 12,600ft. Then those debris popped an estimated 200′ wide persistent slab just below a large cliff band that all continued on down for the rest of its journey.  This same piece of terrain produced a skier triggered slide on Saturday 11/3.  It released a bit to the lookers left and below the one pictured.  The observation for this avalanche can be found here.

Weather: Broken sky and generally protected from any wind.
Snowpack: Snowpack depth was sharky to 70cm on average, depending on elevation and on slopes exposed to previous wind events. The deepest and most suspect snowpack would have been on the true north facing slopes above 11,400ft. Winds associated with 11/4 had raked or pressed a lot of those more northerly slopes and loaded the more northeasterly slopes in this area. Observed new snow drifts up to 40cm, but the 11/4 storm probably brought in around 15-18cm’s HST at the upper elevations we were traveling in. The new snow felt slabby from the wind and sitting on junk that you could type another paragraph about.  Sandwiched in between the past few days snowfall and the faceted snow from the 10/9 and 10/11 snow events was a thin 1finger hard crust.  Outside of observing a good sized natural avalanche, we observed one large collapse that sent shooting cracks for 100-200′ on the deepest part of a slope, the shaded, most northerly facing, and further not stripped by recent winds… part of that slope. The slope angle at the cracks were at or above 40 degrees. The cracks didn’t appear to continue into the more northeasterly part of this slope.

Photos:

Eased into slope expecting a good collapse. Shooting cracks up the most shaded part of the slope along the left side of the picture and into the rocks above. Cracks didn’t appear to run out into the middle of the bowl. HS increased from ~40cm’s to ~90cm’s where we finally got the collapse.