Tuckerman Ravine below Right Gully at 4600 feet elevation.

20240102 Obs

Today the forecasting team went into Tuckerman Ravine with the goal of assessing the sensitivity and distribution of the new wind slab. It was actively snowing with moderate winds. Visibility was obscured from blowing snow and temperatures were approximately mid teens. We noted various bed surfaces as we traveled. Some areas were wind scoured with a thin ice layer. Other areas had soft snow that skis and boots could penetrate and still other areas had stiff wind affected snow.

We dug a pit in a wind slab below Right Gully and found a fairly cohesive finger hard wind slab from snow in the past 24 hours. We were on a southeast facing aspect at 4600 feet elevation. The slab was 42 cm thick and resting on the stout ice crust from the January 10th storm. This interface seemed well bonded. Within the windslab, two distinct layers were found with a 4 finger hard interface. During shovel-shear tests the top 15 cm of the slab was failing on isolation at this interface. This reactivity was not what we expected, however, because of the strong winds and new snow, our location was not necessarily representative of other terrain.

Take-aways:

• An accurate assessment of distribution could not be made because of limited visibility.
• Significant snowfall rates while we were in the terrain and exiting along with light to moderate winds were actively loading east facing terrain.
• In our test pit and in hand-shear tests while traveling, the sensitivity of the wind slab problem ranged from sensitive to stubborn.