Avalanche Forecast
Issued: Feb 17th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Storm Slabs.
dsaly,
Avalanche Canada
Dig down and investigate the bond between the recent storm snow and old surface snow before committing to big terrain. Be mindful of reactive wind slabs as you move around ridge features and wind-loaded terrain.
Summary
Confidence
Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.
Weather Forecast
MONDAY NIGHT: Partly cloudy. Alpine low temperature -12 C. Northwest wind 20-30 km/hr.
TUESDAY: Mix of sun and cloud. Alpine high temperature -3 C. North-northwest wind 15-25 km/hr
WEDNESDAY: Sunny. Alpine high temperature -2 C. Northwest wind 15-35 km/hr.
THURSDAY: Mostly sunny. Alpine high temperature -7 C. Southwest wind 10-15 km/hr.
Avalanche Summary
This past weekend a reactive storm slab developed from 20-40 cm fresh snow, with higher snowfall amounts favoring the eastern part of the forecast region.Â
On Saturday, storm and wind slab avalanches size 1-1.5 were triggered by skiers, along with loose dry sluffing in steep terrain. In sheltered terrain, avalanches failed on a reactive layer of surface hoar buried by the storm snow. Overnight Saturday and into Sunday, the reactive storm slab produced a size 1-2 natural avalanche cycle.Â
Through Sunday, skier traffic and explosives continued to trigger size 1-2 avalanches. Storm slab avalanches were reported at treeline and below, with many reports on northeast to northwest aspects; a layer of surface hoar 20-40 cm is the likely culprit. At treeline and above, naturally failing and skier triggered wind slab avalanches were observed on south and east aspects.Â
Snowpack Summary
20-40 cm new snow over the weekend covered a variety of surfaces: hard wind slabs around ridgetops and northerly alpine features, soft slabs and 10-15 cm of lower density snow in sheltered terrain, a thin sun crust on solar aspects, and scoured features in exposed terrain. A reactive layer of surface hoar has been the weak layer in many recent storm slab avalanches around treeline and below. In the alpine west-southwesterly winds have developed reactive windslabs with the touchiest deposits in lee-ward and cross-loaded terrain. Â
A thick rain crust to mountain top sits 10-40 cm of below the surface in the east of the region and 40-100 cm in the west. Reports suggest the bond is improving, and the midpack below the crust is wll settled. Weak facet/crust layers near the base of the snowpack have not been an active avalanche problem recently.Â
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
Problems
Wind Slabs
West-southwesterly wind has redistributed the recent storm snow. Use caution around steep ridge features and immediate lee and cross-loaded terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
20-40 cm snowfall over the weekend has developed as a slab. In more sheltered terrain this slab overlies a reactive layer of surface hoar which could make it touchier than expected, especially in the trees. Solar input could make this slab more reactive, don't lower your guard as the sun comes out.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Feb 18th, 2020 5:00PM
