Sea to Sky Avalanche Forecast
Feb 23rd, 2012 9:46AM
Fair - Intensity of incoming weather is uncertain
An approaching low pressure system will bring moderate-heavy precipitation to the coastal regions beginning Thursday night through to Saturday. Friday: Snow amounts 20-30cm. Ridgetop winds 50km/hr gusting 80km/hr, easing from the SW in the afternoon. Treeline temperatures near -5. Freezing levels 700m. Saturday: Snow amounts near 5cm. Ridgetop winds light -moderate from the NW. Freezing levels at valley bottom. Sunday: Light flurries during the day. Ridgetop winds light from the NW. Freezing levels valley bottom.
Several size 2 skier triggered avalanches occurred on Northerly aspects above 1900m. One of these include a skier remote from 20m away, the propagation was surprisingly wider then expected. Wind slabs continue to build on Northerly aspects, they sit on weak facetted surfaces, and lower density snow. With new snow and strong winds I suspect wind slabs will continue to form, and storm snow instabilities to exist into Saturday.A Special Avalanche Warning has been issued for the South Coast Inland, and Interior regions. Keep yourself informed by reading the daily updated Avalanche Bulletins, the Special Warnings, and knowing the conditions in your "local" mountains.
New snow and wind have formed wind slabs at higher elevations on NW-NE slopes. These wind slabs sit on a variety of old snow surfaces. These old surfaces are now 30-45cm down and include crusts that exist on all aspects at lower elevations and on steep solar aspects higher up. Facets (sugary snow crystals) and spotty surface hoar (feathery snow crystals) may also exist in combination with crusts, so there may be slab reactivity at lower elevations. With more storm snow and wind in the forecast the new load may have a poor bond to the underlying buried surfaces. The mid and lower snowpack are strong and well settled. The average treeline snowpack depth is about 240cm.
Strong winds and new snow have created wind slabs in the alpine, and exposed areas at treeline or below. Wind slabs are likely sensitive to rider triggers.
Aspects:North, North East, East, South East.
Storm slabs will continue to form at all elevations with forecast snow. They may be particulary reactive where they exist in combination with buried crusts, facetted snow, and/ or in sheltered areas where buried surface hoar.
Valid until: Feb 24th, 2012 8:00AM