Snow and wind will continue to build wind slabs in alpine lees and exposed treeline features. These slabs may be poorly bonded to the underlying crust. Watch for sluffing in steep terrain and loose, wet releases on sunny and low elevation slopes.
Summary
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
TONIGHT: Mostly cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate to strong, southwest. Alpine temperature near -5. Freezing level 1200 m.SUNDAY: Cloudy, flurries. Accumulation trace. Ridge wind light to moderate, southwest. Alpine temperature near -3. Freezing level 2000 m. MONDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate to strong, southeast. Alpine temperature near -4. Freezing level 1800 m.TUESDAY: Mostly cloudy, flurries. Accumulation 5-10. Ridge wind light to moderate, northwest. Alpine temperature near -5. Freezing level 1600 m.
Avalanche Summary
Friday several skier-triggered, size 1.5 wind slab releases were reported on north aspects at 2300 m. As well as a few solar-triggered storm slab releases (size 1.5) on steep, unsupported. west-facing features at 2200 m.Wednesday there was a report of an icefall-triggered size 1.5 wind slab (50 cm deep and 50 m wide) on a north aspect at 2400 m. On Tuesday a skier triggered a size 1 wind slab 20 cm in depth on an east facing feature at 2400 m. And on Monday wind loading produced natural wind slab avalanches to size 2 on north facing terrain around 2400 m. Solar radiation also produced natural storm slab and loose wet avalanches to size 2.5 on various aspects between 1700 and 2600 m. We received the following information second hand, and not all details may not be accurate. Last Sunday six riders were involved in an avalanche up Doctor Creek. One was stuck, the second went to help and also got stuck, a third rode up to help and triggered an avalanche that buried all three, "up to their faces." The riders credit airbag packs with saving their lives and although one sled was wrecked, was able to extricate themselves. The slope was reportedly north facing and failed as a wet slab.
Snowpack Summary
About 5-15 cm on new snow overlies a crust on all aspects to at least 2000 m (and possibly higher on south-facing slopes), while 20-30 cm can be found at higher elevations (and up to 50 cm in some areas in the northwest of the region). There are now a few different crusts within the top 50 cm of the snowpack, with only the mostly recently buried crust posing a concern in wind-loaded areas.There is some lingering concern around the mid-March Persistent Weak Layer (PWL) in the alpine where it is found 50 to 90 cm below the surface. This buried crust/surface hoar interface was widely reactive but has produced only isolated avalanche activity in last week. It is likely trending towards dormancy, but we need to keep it in the back of our minds as it is capable of producing large avalanches should it be triggered (think step-down from a surface avalanche or cornice collapse)Deeper persistent weak layers from December and January are considered dormant at this time.
jmcbride,
Avalanche Canada
