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Small Wind Slab Avalanche, Middle Peak, Castle Lake
We triggered a small avalanche on a test slope by cornice fall today. The result was a small wind slab avalanche. It was approximately 20 feet wide and 20 feet long. The bed surface was a thin icy crust. The crust was 12 inches deep in a pit we had dug earlier. Temperatures were warming up and snow surfaces were beginning to feel moist and heavy. The trees were dripping melting snow.
- Observation Location: Castle Lake
- Elevation: 6200 Feet
- Date: 20210215
- Time: 1130
- Observer: Ryan and Aaron
- Sky Conditions: Scattered (SCT) - Periods of fog and scattered clouds at various altitudes.
- Current Precipitation: NO
- Air Temperature: 39 °F
- Surface Penetration: Ski penetration (PS) = 6 in (15 cm), boot penetration (PF) = 12 in (30 cm)
- Total Snow Depth (HS): 80 in (205 cm)
- 24-hour New Snow Depth (HN24): 3 in (8 cm)
- 24-hour New Snow Water Equivalent (HN24W): 0.35in (8 mm)
- Wind Direction: SW
- Wind Speed:Light (L), 1-16 mi/hr, twigs in motion
- Column & Block Tests:
- Slope Angle & Aspect: 40º, NE - test slope. 30º NE- snow pit
- CT13 SC ↓ 12 in (32 cm)
- Avalanche: SS-AC-R1-D1
Snow shower continued until 9 a.m. Fog would move in and out with scattered clouds as we toured up to Middle Peak. Temperatures were rising. A high of 43.5 ºF was recorded at 1 p.m. at our Castle Lake weather station. Roller balls and pinwheels were forming on south aspects. It would have been a perfect day to build a snowman. Moist packable snow was everywhere.