Expect poor snow quality due to massive amounts of recent rainfall.
Weather Forecast
After a warm and rainy storm, we will see a return to winter. For today, SW moderate winds gusting to 50km/h, 4cm of snow and freezing levels below 1300m. Expect cooler temperatures and scattered flurries heading into the weekend. A frontal system arrives early Sunday morning with warming temperatures and up to 35cm of snow.
Snowpack Summary
65mm of rain has fallen at Rogers Pass over the last 3 days. The added moisture has dramatically changed the snow quality from early season powder to a saturated upper snowpack capped by a thin surface crust. In the alpine, extreme southerly winds have created a wind slab problem on lee features. October 31 crust is buried 100cm at treeline.
Avalanche Summary
A widespread nature avalanche cycle occurred yesterday with the ongoing rainfall and strong winds. Several large size 3.0 wet slab avalanches were observed in the highway corridor. Artillery avalanche control produced large avalanches in the east end of Rogers Pass. A size 3.0 natural avalanche was observed on the Thorington route of Mt Jupiter.
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.