Mammoth Rock Bowl, Sherwin Trees: Warming

Mammoth Rock Bowl, Sherwin Trees
Submission Info
Saturday, March 31, 2018 - 2:45pm
Red Flags: 
Rapid warming
Mammoth Rock Bowl, Sherwin Trees 37° 36' 40.428" N, 118° 59' 31.956" W
Snowpit Observations
More detailed information about the snowpack: 

Observer: d lewis
Loc: Mammoth Rock Bowl
Lat/Lon:37.6112, -118.9922
Elevation: 9600 f
Aspect: NE Angle: 33°
Signs of Instability: Pin Wheels
Sky Cover: BKN
Precipitation: No Precipitation
Wind Speed: Calm Beaufort
Current Temp:5 to 10°C Trend:➚
Snow Stability: Good
Stability on similar slopes: Good
Avalanche Danger: Moderate 4 Stability Tests: CT28 Q2 130cm CT22 Q2 35cm CT27 Q2 0cm CT26 Q2 35cm

Comments: Toured up the Mammoth Rock trailhead to monitor the warming of the lower and mid elevation in the Mammoth Rock/Bowl portion of the Sherwins. Mammoth Rck. Trlhd. (Elv. ~8300’) ~2’ base. Snow became isothermal, unsupportive, and very punchy by mid afternoon up to  ~9000’ on NW-N-NE aspects. Above ~9000’, top 4 to 10 cm, poly crystals on NW-NE aspects. Below, rounding grains, moist.  Ambient air temperatures + 13C (~56F) mid PM at ~8300’, +6C (~43F) at 9600’. My mid afternoon the snow below ~8800’ on NW-N-NE aspects is mostly unsupportive. Above, ski penetration ~10cm (~4”) and generally supportive, becoming less so on NW aspects. The recent warming has effected to top 10 to 40 cm (depending on elevation). Lower elevations have cycled through several melt/freeze cycles with sufficient melt water and is transitioning toward a spring snowpack of mostly poly crystals with a melt freeze crust at the surface. Mid elevations on NW-N-NE aspects the top ~20 cm (~8”) is transitioning to a spring snowpack with cold(ish) snow below. Saw a few rollerballs originating from steep rock outcroppings but no new Loose Wet releases noted. However, in mid to lower elevation, steep complex terrain, ski triggered releases likely in the PM hours. With the recent emergence of spring, creeks are beginning to flow and snow bridges are beginning to recede or fail making water crossing more difficult.    

Weather Observations
Blowing Snow: 
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Thin mid-level clouds (alto stratus?) through the day. Light westerly winds at the trailhead, calm once you ascended above ~ 8400'. 

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