Regions
Northwest Coastal.
Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
An approaching low pressure system will bring light-moderate precipitation to the NW regions Thursday night through to Saturday. Friday: Snow amounts 10-20cm through the day. Ridgetop winds 30km/hr from the SE. Treeline temperatures near -7. Freezing levels 200m. Saturday: Light snowfall amounts. Ridgetop winds light-moderate from the SE. Freezing levels remain at valley bottom. Sunday: A ridge of high pressure will bring dryer, cold conditions.
Avalanche Summary
Reports across the region of widespread size 1-2 natural avalanche activity. Majority of aspects being NE-N. Many of these are reported as wind slabs releasing on buried crusts that formed mid February. In the Eastern area of the region a size 2.5 natural avalanche occurred on February 21st. This occurred on an East aspect @1700m, running 900m in length. Wind slab activity up to size 2 on Southerly aspects have also been reported. On February 20th a natural size 2.5-3 was reported from Mt. Rainy. With forecast wind and snow for Friday, I suspect avalanche activity to increase.
Snowpack Summary
Generally, up to 35 cm of new snow sits over a strong melt freeze crust that exists below 1000m on all aspects, and over wind-pressed powder on shaded alpine features. Facets and spotty surface hoar have been found sandwiched between the newer snow and the old surfaces at treeline and below. This surface hoar seems to be more predominant in inland areas. Where it exists, this layer has started to become reactive under the new load and slab development. I suspect this will continue as the forecast snow and wind continues. The mid and lower snowpack is generally well settled and strong. Check out our Forecaster's Blog for some insight on incremental loading. A Special Avalanche Warning has been issued for the North Coast Inland, and Interior regions of BC. Some of these problems may exist in the eastern parts of your region, but reports suggest it's not a widespread problem. Keep yourself informed and up to date by reading the current avalanche bulletins, the special warning, and be aware of the snowpack conditions in your "local" mountains.
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.
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.