Mammoth Rock, Mammoth Basin (1/9/17) - Skinned up from the end of Old Mammoth Road to above Mammoth Rock around 9250 ft and back down the same way. Passed two seperate debris fields. Debris piled up around a foot above snow against the uphill side of trees, some blocks up to 1 ft by 1 ft visible under new snow. Both were under steep cliff bands west of the Rock. One started around 9,000ft the other around 9,400ft, both crowns were obscured by new snow. There were settlement cracks around many trees throughout the approach. Cracking around skis was common, no shooting cracks. Isolated collapsing when I moved into a wind loaded area. Two hand shear tests, both failed easily 25 and 30 cm down. Seemed to be a thin layer of larger crystals where the failure occured. In both locations I found 10 cm of fist hard new snow on the surface, 5 cm 1F wet snow under that, and 35 cm fist hard snow below that.
Avalanche Observation, Tele Bowls, Mammoth Basin (1/9/17) –
Slope: 35degrees, Trigger type: Natural
Aspect: North, Weak Layer: Other - explain below
Avalanche Width: 500ft., Terrain: Below Treeline
Elevation: 8,700ft., Bed Surface: Other - explain below
Avalanche Length: 1,000ft., Number of similar avalanches: 2
More detailed information about the avalanche: R4-D3.5 (large relative to path, could damage a railway car, destroy a car, a wood frame house). Looks to have gone naturally during heavy rain event last night/yesterday. Wet slab. 2.5ft+ crown, wrapping around upper parts of both entire bowls. Northerly facing bowls, starting zones in the low 30s for the most part. Failed and ran on top of upper October rain crust (~15cm above ground). Underneath this rain crust was mix of frozen basal ice and 2-2.5mm facets. Entire snowpack to ground, save for top few inches of new dry snow, was quite moist. 12'+ debris piles in bottom portion of bowls. Some small trees were taken out, along with some 10" diameter dead ones. Of note, avalanches ran in forested areas adjacent to open bowls in the lower 1/2.
*Skiing and riding has now gone to crap in the bowls, between firm shallow bedsurface with icy spots to frozen chunder avy debris (hard to walk thru, let alone navigate a ski or board).
Punta Bardini/Old Growth, Mammoth Basin (1/9/17) - Route: Propane tanks up Old growth to summit, back down, thru Tele bowls. Both Tele Bowls ripped out huge during heavy rain/storm event yesterday or last night. Snow pack was wet underneath top few inches of new snow from this morning to the ground below ~8900'. Above this, snow pack was moist to ground up past at least 9,300'. 5cm thick rain crust at surface from last night/yesterday at the summit ~10,100', where new snow has blown off and not stuck. Pit dug to ground at 9,300', northerly aspect. See attached profile. Of note, snow was moist to the ground, and almost entirely isothermal (0 deg throughout except for a portion in middle with was -0.5- -1.0deg C, and very surface). Stability tests (CT and ECT) did not show any concerning results (rough fractures with moderate to hard force, no propagation in ECTs). No woomphing, cracking, or other signs of instability (remember, Punta Bardini is mostly fairly sheltered and relatively low elevation). Skiing/riding conditions very good above 8,900'! (3-5" nice fresh powder on top of supportive moist snow). Below 8,900', rain crust seemed to be more distinct and breakable, requiring a little more light-footed-ness. Below 8,500', even less new soft surface snow, and more punchy rain crust.
Mammoth Mountain Ski Patrol, Mammoth Basin (1/8/17) - Widespread avalanches triggered by explosives and ski cuts throughout mountain at all elevations. 12" crowns around Lincoln Mtn (10,000'), propagating across entire ridglines. Up to 36" crowns on main lodge side - upper cliffs (9,600'), lower cliffs. Debris from gun shots on upper mountain from Scotty’s and Paranoids running far down the mountain with debris piles 6ft deep in bristlecone and running within 10ft of the patrol avalanche closure near Terry's run. Monday Morning (1/9): 1-1.5" think rain crust on surface in the Bear, with several inches of dense snow on top at 9am. Thick dense snow underlying rain crust. Slopes at 9,800' 7-8" new dense snow on top of 2-3" moist slush layer. Lincoln Mtn: 1-2' crowns top of Avy 1 & 2 (new blown in snow sliding on top of bullet proof ice crust from yesterday / last night's rain layer freezing). Several patrollers hitting ice layer, loosing edges and going for scary slides.
Sierra Front, Tom’s Place to June Lakes (1/8/17) - Avalanche Type: Wet Slab, Loose Wet/Point-Release, Storm Slab
Slope: 35degrees, Trigger type: Natural
Aspect: Northeast, Weak Layer: Storm Snow
Terrain: Below Treeline, Elevation: 9 000ft.
Bed Surface: Unknown
More detailed information about visible avalanches:
Quick road tour this afternoon while there was a break in the weather. Noted wide spread natural activity from Convict Lake to June Lakes.
- Rock Creek to McGee - still not cleared.
- Convict Lake - Avalanche activity visible from the lake on both sides of the valley (Mt. Laurel, Mt. Morrison), unknown start, ran short of the lake elevation.
- Solitude - debris visible in Banana Chute, start unknown.
- Punta Bardini - start unknown, debris to the young growth in the runout. D2-
- Mammoth Bowl - debris visible in the upper bowl, crown partially obscured, visible 1-2' x 200'. D2
- Dempsey's Don't - debris visible in the top end, unknown runout. D2
- Mammoth Rock - Loose/Wet x 2 ~ 8,700 and below, possibly running to ground. Numerous small Loose/Wet running short distances. D1
- Carson Pk. and visible terrain north - extensive debris visible in Devils' Slide. Debris from central face in runout D2. Two debris fields D2 running just south of Silver Lake.
- Sierra Front - numerous Loose/Wet starting at ~ 8,700' +/- from Mammoth Rock south to McGee Creek. D1 - D1+. Most active areas where there was little snow prior and recently loaded by the latest series of storms. As you move east of the crest rain up to 8,000', wet snow up to 9,000', heavy dense snow fall above, 10,000'. One to three feet new snow along 395 from Mammoth to June Lake.