Wind slabs developed through mid week thanks to strong SW winds and ample snow available for it to transport onto leeward slopes. The few observations we have received show that while the wind remained strong through yesterday, less and less loose snow has been blowing. Wind slabs can take days to stabilize and there may be a few still sensitive enough to trigger if you venture into extreme terrain above treeline. Look for the most recently deposited drifts just under cornices and near the tops of steep chutes and gullies.
While the chance of triggering the persistent weak layers buried by the storm last week is increasingly unlikely, deep slab avalanches are hard to predict and have high consequences. The last reported collapse of the buried weak layers was on the 6th, but snowpack tests have continued to indicate that failure in these sugary snow grains is not impossible. A group of riders hitting just the wrong place, a large cornice drop or avalanche running down and overloading the underlying snowpack, landing a big jump, these are the types of triggers that could still affect these deeper weaknesses. The resulting avalanche could be quite large. It’s a low probability-high consequence situation. The best way to know what these layers are doing on the slopes where you want to play is to dig down and check on them. They will probably be down around 3 to 4 feet deep on northerly slopes. Areas that already had some snow prior to 3/1, and areas where that snow was deep enough to cover over brush and small trees that would otherwise anchor the slab in place are the most suspect.
The chance of snow showers will increase throughout today with light winds. An inch of new snow is unlikely to create new avalanche problems today, but more overnight may continue to keep the scales tipped slightly in favor of instability through this evening and tomorrow. Mostly cloudy skies may have allowed more snow to melt at lower elevations last night, but will most likely keep solar radiation from wreaking too much havoc today. Some rollerball activity is possible, but loose wet avalanches are pretty unlikely.
