http://www.pc.gc.ca/apps/links/goto_e.asp?destination=http://data.avalanche.ca/Images/SPAW%20Feb%207%202019.pdfCold related injuries are a real possibility today. Pay special attention to new wind slab development on southerly aspects in the alpine, and buried surface hoar below treeline.
Weather Forecast
Cold temperatures will persist into the foreseeable future. Sunny today with no signs of precipitation. The alpine temperature will climb to -20, although it is presently -26 at 2000m. Ridge winds from the E, 20 km/h. There is a real risk of cold related injuries such as frostbite.
Snowpack Summary
Strong to extreme north winds created wind slabs and loaded pockets on lee features. Wind slabs sit atop a crust on steep solar aspects in the alpine. Cold temperatures are promoting near surface faceting. The storm snow has settled to ~50cm. The Jan 31 and Jan 17 interfaces (surface hoar and sun crust) are down ~50cm and ~70cm at tree line.
Avalanche Summary
No new avalanches were observed yesterday.
Confidence
Wind effect is extremely variable
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.