Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
You may be able to trigger a wind slab 6-12" thick today. 3-6" of recent snowfall, coupled with shifting westerly winds, and small amounts of snow available for transport will create sensitive conditions. Wind slabs will be thickest and most sensitive above 7000', on east-facing terrain, especially near ridgetops. Winds have shifted from SW to W to NW and may shift to N later today. Local terrain features may alter prevailing wind directions. Watch out for wind slabs on terrain across the compass. Pay attention to obvious signs of wind loading such as drifting or pillows. Look for signs of instability within the new snow such as shooting cracks from your skis, sled, or board. If you're observing signs of instability, it's time to switch to a different aspect or back off slopes steeper than 30 degrees.
Additional Discussion:
New snow is falling on a variety of weak snow, such as surface hoar and crust/facet combinations. The location and size of the wind slab problem have been expanded to encompass uncertainty around newly buried weak snow. Wind slabs will be thickest above 7000' in wind prone areas. However, recently buried surface hoar would be most reactive in wind sheltered terrain (think those protected pockets on steep, treed slopes below 7500'). The crust/facet combination buried 10-12" down is elevation dependent. Areas where this weak layer combination could be most dangerous is below 8000', across all aspects. With new snow falling on weak layers, pay attention to collapsing within the snowpack (i.e. audible whumpfing sounds). Before committing to steep slopes, dig into the upper snowpack to see how the new snow is bonding to previous snow and if buried weak layers are present.