Regions
Kootenay Boundary.
Fresh slabs overlie an old crust on most aspects, and buried surface hoar on north aspects in the alpine. Assess the bond between the new snow and the old surface before committing to bigger slopes.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
TONIGHT: Cloudy, flurries. Accumulation up to 5 cm. Ridge wind moderate, southwest. Alpine temperature near -10. Freezing level lowering to 500 m.SATURDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind light to moderate, southwest. Alpine temperature near -8. Freezing level 1200 m.SUNDAY: Increasing cloud in afternoon. Ridge light, southwest. Alpine temperature near -5. Freezing level 1500 m.MONDAY: Increasing cloud in afternoon. Ridge wind light, southwest. Alpine temperature near -5. Freezing level 1500 m.
Avalanche Summary
Reports from Thursday included activity in the recent storm snow including sloughing and small (size 1) storm slab releases from 10 - 20 cm thick above the most recent crust.Prior to Thursday storm there were no significant avalanche observations to report from earlier in the week.
Snowpack Summary
Around 10 - 15 cm of new snow has fallen with moderate southeast wind. This snow sits on a mixture of weak grains including a slippery crust that is present at all elevations on solar aspects and all aspects below 1900 m elevation. On northerly aspects at and above treeline the new storm snow is burying a mix of large surface hoar and surface facets.Two other weak layers are present in the upper snowpack. The mid March interface is down 20 to 30 cm and it resembles the old surface; crust on solar, surface hoar on high elevation north.The early March interface is 35 to 50 cm below the surface and is similar in composition to those listed above.A few other persistent weak layers are buried in the mid and lower snowpack, but they have gone dormant and are unlikely to resurface until we move into a period with consecutive above-freezing nights later in the spring.
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.