South Columbia

Wind is the critical factor and reactive wind slabs on a variety of aspects may be lurking.

On Tuesday, a natural wind slab event was reported up to size 2 on a variety of aspects with one notable size 3 that ran on a SE slope at 1360 m. Switching winds from North to the West on Thursday will likely promote a reverse loading pattern increasing the likelihood of rider triggered wind slab activity on a variety of aspects.

Moderate - Wind effect is extremely variable

Arctic air continues to be entrenched in the South Columbia region. The pattern will start to shift Thursday to a zonal flow, allowing Pacific frontal systems to make way into the Interior early next week. Little change expected for the weekend.Thursday/ Friday/ Saturday: Mix of sun and cloud with a slight alpine inversion bringing temperatures near -15 and valley bottoms -20. Ridgetop winds light-moderate from the West.

Up to 30 cm of low density snow fell earlier this week. Moderate to strong southwest and then northerly winds have shifted these fresh accumulations into wind slabs in exposed terrain. Recent snow has covered old, thicker wind slabs from previous wind events. The mid-December facet/surface hoar persistent weakness can be found buried 70-120 cm deep and is generally considered dormant. However, we are still receiving occasional reports of sudden results in snowpack tests, suggesting that it has to potential to propagate into a large avalanche if triggered, particularly in shallow spots where this layer is closer to the snow surface. The lower snowpack is well bonded and features a thick rain crust near the ground.