A touchy weak layer, forecast snow and strong winds will likely produce dangerous avalanche conditions.
Summary
Confidence
Fair - Intensity of incoming weather is uncertain on Friday
Weather Forecast
Thursday: A ridge of high pressure brings dryer, cooling conditions. Alpine temperatures near -6. Ridgetop winds 30km/hr from the NW. Friday: Snow amounts 10-20cms during the day. Ridgetop winds moderate from the SW. Treeline temperatures near -7. Saturday: Snow ending early in the morning, with continued light flurries. Possible sunny periods in the afternoon. Freezing levels should remain at valley bottom through the forecast period.
Avalanche Summary
Recently submitted near Smithers, on Mt. Evelyn's South face was a size 3 slab that was skier triggered. This was on a SE aspect@ 1800m. The report indicates a wind loaded slope. For more details visit the link below. On Tuesday a size 2.5 and a size 2 natural slab avalanches were reported. These occurred in the western part of the region, on E-S aspects @ 1700, 1400m. The 2.5 ran 900m in distance. I'd be very cautious right now. With more snow and wind forecast, I suspect the mid-February buried surface hoar layers will become reactive creating dangerous avalanche conditions. Please visit this link to view full details of an avalanche report submitted today. http://www.avalanche.ca/cac/library/incident-report-database/view/360158b8-5627-4c4b-8726-c25bde927f18
Snowpack Summary
About 25 cm of snow that fell over the past week sit on a variety of old surfaces. These surfaces include: melt-freeze crusts that exist on all aspects at lower elevations and on south-facing slopes higher up and well-settled powder on shaded aspects in the alpine. Weak surface hoar crystals (size 3-4mm) are sandwiched between the old surfaces and the newer snow and have recently shown easy compression test results. The distribution of the surface hoar seems to be up to treeline on all aspects and on sheltered features in the alpine. This upper snow pack structure will be the big thing to watch as the overlying slab develops. I expect to see gradually increasing reactivity in the surface hoar interface with incremental loading and higher winds forecast for this week. Check out our Forecaster's Blog for some insight on incremental loading and the "Tipping Point" The mid and lower snowpack are generally well settled and strong.
swerner,
Avalanche Canada
