Throughout the Uinta Mountains, there is a slab 2-5 feet thick resting on a persistent weak layer (PWL) of facets about a foot above the ground. This PWL exists on most slopes except ones facing due south and southwest.

This PWL has adjusted to the weight and stress of new snow that fell last week, and the likelihood of triggering an avalanche has gone down. However the snowpack layering remains the same, and the consequences of an avalanche remain deadly. The most likely slopes to avalanche are ones with the added weight of wind drifted snow. The most likely trigger points are (1) where the snowpack is generally thinner, (2) near the edges of drifts, or (3) in thin spots near rocks.

Areas with deeper snow make it harder for a skier or rider to impact facets near the bottom of the snowpack. In the large avalanche Craig describes in the video above, several explosives were deployed on that slope with no effect. That avalanche didn't happen until an explosive went off in just the right spot. This means we can ride a slope and it may not avalanche until someone rides over a thin spot.

Below is an image of the snowpack in the Mill Creek area just east of Bear River from Tuesday. Notice the weak snow near the ground highlighted by Ted's snow saw.

Strong northwest winds blew on Tuesday followed by strong northeast winds yesterday morning. This morning strong winds are blowing from the west and southwest.

These winds have formed slabs of wind drifted snow on many different aspects mostly at upper elevations above treeline. These wind slabs can produce an avalanche on their own. These wind slabs also add weight and stress to weak, faceted snow near the ground.

Today and especially tomorrow, drifts and wind slabs that formed this week will be covered in new snow and harder to see.