Freezing levels may rise higher than forecast. Where rain falls it will saturate the upper snowpack and cause loose wet and wet slab avalanches.
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Synopsis: A series of fronts is sliding down the BC coast. The warm front should pass over the South Coast on Saturday, followed by the cold front Sunday morning. Expect up to 30cm of snow at upper elevations before conditions dry out briefly on Monday.Tonight and Saturday: Heavy snow / Moderate to strong SW winds / Freezing levels 1500mSunday: Heavy snow / Moderate to strong SW winds / Freezing levels 1700mMonday: Flurries / Light W to NW winds / Freezing levels 1300m.
Avalanche Summary
A large natural cycle of loose wet avalanches up to size 3 was observed in the Coquihalla area Thursday.
Snowpack Summary
Coquihalla and south: Strong southerly winds have redistributed some of the new snow and formed thick wind slabs in exposed lee and cross-loaded terrain. Up to 100 cm of storm snow has fallen in the past few days. This new snow may feel upside down due to warming temperatures later in the storm, and it appears to be bonding poorly to the early March melt-freeze crust. The mid February weak layer of crusts and facets, now down over 200 cm deep, has been reported to be rounding and bonding.Duffey Lake and north: New dense wind slabs are likely in exposed NW-E facing terrain and cross-loaded features. The early March melt-freeze crust can be found down 40-60 cm everywhere except high north aspects. The mid Feb weak layer is generally now found down 70-120 cm. Recent snowpack tests continue to give popping shears where this layer is less than 100 cm deep. Deeply buried weak layers of facets and depth hoar remain a concern on high alpine slopes with thin or variable snow cover.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.