Rock Creek

Submission Info
Wednesday, April 12, 2017 - 12:00pm
Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Rapid warming
37° 26' 26.8584" N, 118° 43' 38.1864" W
Snowpit Observations
More detailed information about the snowpack: 

Route- Skinned up through the East Fork Campground from the parking are on Rock Creek Rd., up the Tamarack moraine on the E side of the canyon and S along the moraine to the top of northern most shoulder of Mt. Morgan S. Skied NE, N, and W aspects back down to the road and back to the car.

1000 at 9000' in a meadow just up canyon from the campground, NW aspect- Foot pen = 5cm, Sky =  clear, Wind = light from the W, Tair = 9 C, Tsurf = 0 C, T-20 = -2 C, surface snow was a 4cm melt-freeze crust. Moderate blowing snow visible on the E ridge of Mt. Morgan S. Roller balls from the past few days observed on low elevation E aspects.

1040 at 9865' on the top of the Tamarack moraine, NW aspect- Foot pen = 30cm, Sky = clear, Wind = light from the W, Tair = 8.5 C, Tsurf = 0 C, T-20 = -4 C, surface snow was still melt-freeze, becoming moist. No sign of new snow from the quick shot of precip yesterday. Moderate blowing snow continuous on Morgan, also some areas of blowing snow on Mt. Starr and Mt. Dade. Roller balls from the past few days visible on ENE aspects below 11000' on the most northerly point of Morgan.

1200 at 11400' on top of the northern most shoulder of Mt. Morgan S, N aspect- Foot pen = 10cm, Sky = clear, Wind = moderate and continuous from the SW with strong gusts, Tair = 4 C, Tsurf = -2 C, T-20 = -3 C, surface snow was small wind blown rounds just barely becoming moist. Some localized wind transported, rolling snow. Looking at the Sierra crest around Rock Creek, only Mt. Morgan's E ridge had continuous wind transport (see video).

Skiing down, snow quickly became wet spring afternoon snow below about 11000'. Triggered many large (3' diameter) roller balls on steep E aspects at about that elevation (see photo). Snow on all aspects was wet and sticky below about 10200'. On the highway from Mammoth in the morning, and back in the afternoon, observed many D1-D2 loose wet avalanches and roller balls from the past few days on E-NE and NW-W aspects at middle and lower elevations, some even starting above 10500'. Hard to tell on the way back if any were new form today. Blowing snow observed on Valentine Peak, Pyramid Peak, Nameless Peak, and the N ridge of Bloody.

Impressions- We are dealing with two different snowpacks and two different problems right now depending mostly on elevation and exposure to wind and sun. Elevations below about 11000' are typical spring melt-freeze with lots of loose, cohesion-less snow melting by noon and elevating the danger of loose wet avalanches. Above about 11000', on specific peaks that have broad plateaus on the windward side (large "fetches") where soft cold snow is still available for transport, wind slabs are still building today. It's not everywhere in the alpine, only on certain peaks with the right combination of topography and snow conditions.

Snowpack photos: 
Triggering Large Roller Balls on Steep Slopes
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Air temperature: 
Wind Speed: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 
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