630am update: Significant overnight snowfall has increased avalanche danger for Friday. Keep decision-making conservative in the wake of the storm.
A weak layer of facets above a crust persists in the snowpack in isolated areas. Storm slab avalanches may step down to this layer resulting in very large, destructive avalanches.
Storm slabs exist on all aspects but will be most reactive on lee northwest though northeast features.
On Thursday the field team reported seeing several size 1 and 2 slab avalanches in the Memekay Peak area. Recent small slabs (size 1-1.5) were also seen on north and east aspects at treeline in the Mt.Washington area.Natural avalanche activity is expected to continue with the stormy weather, and the potential for human triggering is considered very likely.
Storm totals will vary from 50 cm to over 1 m in the west by Friday afternoon. Storm snow continues to build over a widespread crust in most areas, except in the north where storm snow will fall on heavily wind-affected snow.
The mid and lower snowpack is generally moist and well consolidated. A layer of facets exists between two crusts in the mid snowpack, we are uncertain how this layer will react to the heavy load of new snow.
Below treeline areas have now received enough snow to produce avalanches. Watch for "early season" type hazards such as shallowly buried stumps, creeks, and rocks.
Thursday Night
Cloudy with 4 to 13 cm expected in south and western areas. 40 km/h southwest ridgetop wind. Treeline temperature -7°C. Freezing levels drop to 500 m.
Friday
Cloudy with 3 to 10 cm of snow. 30 to 40 km/h southerly ridgetop wind. Treeline temperature -6 °C. Freezing level 600 m.
Saturday
Cloudy with 2 to 10 cm of snow. 10 to 20 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 800 m.
Sunday
Cloudy with 5 to 10 cm of snow. 25 to 40 km/h southeast ridgetop wind. Treeline temperature -6 °C. Freezing level 700 m.
More details can be found in the Mountain Weather Forecast.
