The winds have been moderate to strong over the past few days. Combined with up to 20 inches of new snow now available for transport, these winds have formed and will continue to form slabs of wind-drifted snow on upper- and mid-elevation slopes. Slopes facing SE through N to NW are particularly susceptible. These slabs are most common near ridgelines and on mid-slope features such as gullies and convex rolls.

These smooth, rounded pillows of wind-drifted snow rest on the Dry January weak layer. Alone, they could catch and carry a rider, but when combined with the buried weak layers, they have the potential to trigger much larger avalanches.

Best Bet: Stick to sheltered, lower-angle terrain out of the wind. Watch for drifts, dunes, pillows, and wind-textured surfaces, as these indicate recent wind loading. If the snow beneath your feet sounds hollow, like styrofoam, this is a sign you may have found a slab.

The Dry January Layer (DJL) formed during our January dry spell can be found on upper- and mid-elevation W-N-E facing slopes. This morning, up to 20 inches of snow sits on the DJL in non-wind-loaded areas. This layer is likely responsible for much of the avalanche activity observed yesterday.

Large slabs now exist across much of the range, resting on the very weak DJL. This strong-over-weak structure is very likely to produce large, destructive avalanches that are big enough to bury and kill a person and potentially damage a vehicle. These slabs can propagate widely and may be triggered remotely from a distance. If you’re considering “safe” travel on a ridgeline, remember you could become a hazard to those below if you trigger or remotely trigger a slide on adjacent slopes, especially in busy terrain. Always be aware of who and what is above and below you. Safer riding conditions are found on slopes less than 30° with no overhead hazard.

Wind-loaded slopes mentioned above remain the most suspect.

An example of the poor snowpack structure in a meadow at 7400' off the Alpine Loop Road (E. Fullmer)

On wind-protected slopes and features in the areas that were favored by this storm, such as the Alpine Loop or Provo Canyon, lingering new snow instabilities are still possible today, generally appearing in two ways:

• Storm slabs: Denser new snow may slide on top of, or into, weak old snow. Be cautious of triggering these above terrain traps such as road cuts, creeks, or gullies. Cracking along the snow surface is a sign you’ve found a slab.
• Loose dry sluffs: Unconsolidated dry snow can run fast and far. Small sluffs can knock you off your feet, while larger ones could bury a person. They are most common on steeper slopes, especially where graupel has accumulated.