Wind Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 1–2
Extreme west winds will become more northwesterly Sunday night into Monday. With 6-12" of fresh snow to move around, it's not a question of if but whether where wind slabs will form. NW winds are known to cause unusual loading patterns. The strength of the winds may have formed them further downslope than you'd normally expect including on open slopes below treeline. This will be a tricky day to travel in and around wind-affected avalanche terrain. Avoid open slopes steeper than 35 degrees where you find freshly drifted and wind-stiffened snow. Give cornices a wide berth as you travel along ridgelines and be aware of the overhead hazard if traveling on slopes below large cornices. A cornice fall could trigger a slab avalanche on the slope below.
In wind-sheltered terrain below treeline, you may trigger a storm slab on convex rollovers and very steep unsupported slopes where you find 6" or more of new snow. On the west side of the mountain where more snow is expected, storm totals may be closer to a foot of snow. Use can use small test slopes to gauge how the new snow has bonded to the old snow surface (likely the 3/28 melt-freeze crust).
Example from Mt Hood earlier this month. Winter returned Sunday night. Watch for shooting cracks in wind-stiffened snow. You may trigger a wind slab on nearby slopes.