Avalanche Forecast
Issued: Feb 21st, 2013 9:05AM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Friday
Weather Forecast
Friday: Heavy snowfall / Strong to extreme southwest winds / Freezing level at 1000mSaturday: Light snowfall / Moderate northwest winds / Freezing level at 600mSunday: Light snowfall / Light southwest winds / Freezing level at 1000m
Avalanche Summary
Explosives control produced slab avalanches to size 2.5 in the region. The avalanches, which occurred in the alpine or at treeline elevation, were either older wind slabs or persistent slabs that failed on the February 12th interface.I expect a spike in natural avalanche activity with the weather forecast for Friday. Direct action storm slabs and deeper persistent slab avalanches are very likely with this system.
Snowpack Summary
Between 25 and 55cm of snow is sitting on the reactive surface hoar layer that was buried on February 12th. This interface has also shown reactivity on Southerly aspects where a sun crust formed during the period from February 8th-11th. Buried wind slabs may also exist below ridge crests at higher elevations; but have most likely gained some strength. There are older weak layers that are now buried down around 60-80 cms and also at about 110 cms. These layers have been unlikely to trigger by skiers, but they may still be sensitive to large loads like avalanches in motion or cornice fall.Loading from significant wind and snowfall forecast for Friday will very likely create potent storm slab instabilities as well as increased reactivity on the February 12th interface.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 22nd, 2013 2:00PM