Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 3
Triggering avalanches 1-3' deep on steep slopes facing west through north and east at all elevations is possible, failing on a persistent weak layer (PWL) that formed during the January/February drought. These avalanches may be triggered remotely - from a distance or from below. Avalanches failing on this PWL continue to be reported, with the most recent reported avalanche occurrence from Saturday in Cardiff Fork on a northeast aspect at 9,000':
This has been an especially tricky avalanche problem and many people who have been caught, carried, and buried in these avalanches have significant backcountry experience. Many of these avalanches are being triggered at the mid elevations (8,000' - 9,500') and often in slight openings in otherwise dense trees. The snowpack is unlikely to give you the usual clues of collapsing or cracking and instead will fail on an unsuspecting rider when they are well down onto the slope, perhaps the 3rd, 5th, or 10th rider on the slope. The graphic below (from Drew Hardesty) highlights the reported avalanche activity on the PWL over the past month:
The only strategy for dealing with this tricky and dangerous avalanche problem is to avoid steep slopes facing west to north and east at all elevations.
