Storm Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1.5–2.5
While less intense than yesterday, the storm will continue today with more snow and wind. Unstable slabs of storm snow could exist on many slopes, and human-triggered avalanches will be likely. These could fail on weaknesses formed during the storm like lighter layers of storm snow or graupel. Avalanches large enough to bury or injure people could occur in both wind-loaded or wind-protected areas across all aspects. In areas where wind-blown snow has filled in the downwind side of ridges, gullies, and open slopes, locally deeper and stiffer slabs of storm snow will exist, and the resulting avalanches could be larger. Large and fragile cornices will also lurk above many of these slopes. In areas sheltered from the wind, the storm slabs may be less deep and softer but still dangerous.
The ingredients for avalanches have come together in many places: new slabs of storm snow resting on potentially weak layers. Parties reported triggering avalanches on steep tree-covered slopes on the West Shore and in the Mt Rose backcountry yesterday. Natural avalanches also likely occurred in the last 24 hours. Some slopes may only need a trigger, like a person on the slope, to set them off today.
Recent avalanches, test slope failures, snow surface cracking, and unstable test results can indicate that unstable storm slabs exist. Today, you can enjoy the new snow and reduce your exposure to avalanche problems by recreating on lower-angle, non-avalanche terrain without overhead hazards like other steep slopes or looming cornices. Blowing snow and poor visibility will make knowing exactly where you are and what's above you harder today, so include wider safety margins or buffer zones in your travel plans.
(3/31/2025)
Avalanche on Galena Peak West (Mt. Rose backcountry). Likely triggered by skiers descending. Crown begins one-third way down the chute, then steps down and propagates across rock features across the lower apron. The crown continued out of the frame to the left along the rocks through steep, treed slopes. Approx. crown width ~ 500ft., total length ~ 300ft.