Avalanche Forecast
Issued: Apr 21st, 2019 3:44PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Loose Wet.
dsaly,
Avalanche Canada
Flurries and wind will build thin, reactive deposits through the day and may hide recently formed wind slabs, use caution around cornices and lee terrain. Loose wet avalanches remain a concern, travel early and avoid moist/wet slopes.
Summary
Confidence
Moderate -
Weather Forecast
SUNDAY NIGHT: Cloudy with flurries, trace to 5 cm, moderate south-southwest wind, alpine temperature -2 C, freezing level 1500 m.
MONDAY: Wet flurries and alpine snow, 5-15 cm snow, moderate southwest wind, alpine temperature 0 C, freezing level 2100 m.
TUESDAY: Cloudy with isolated flurries up to 8 cm by morning, light to moderate west-southwest wind, alpine temperature +1 C, freezing level 1800 m.
WEDNESDAY: Mix of sun and clouds, light southwest wind, alpine temperature +2 C, freezing level 2000 m.
Avalanche Summary
On Saturday morning around the Whistler Backcountry, a natural wet loose avalanche cycle to size 2 was observed on all aspects from 1900-2200m. Wet slab avalanches to size 3 were observed on loaded northerly features in the alpine. Natural cornices failures to size 2 were also observed and explosives triggered cornices size 2-2.5. Further south in the region, cornices failing naturally triggered large (up to size 3) slab avalanches on the slopes below.
On Friday morning, explosives triggered two wet loose size 2 avalanches and several size 2 cornices, in some cases cornices triggered wet slab avalanches to size 2 on the slopes below. One natural storm slab avalanche was observed on a north aspect, the likely trigger a natural cornice failure on the slope.
On Thursday night and into Friday, a loose wet avalanche and cornice cycle occurred in the region during the storm, producing small to large avalanches (size 1 and 2). Most of the avalanches occurred in the alpine as well as treeline.
Snowpack Summary
Recent snow and rain, coupled with warm temperatures and rising freezing levels produced a natural avalanche cycle over the weekend. A crust has developed on most slopes except for high alpine polar aspects where up to 10 cm loose, dry snow is holding on. Cornices and wind slabs have developed with recent strong south winds. The snowpack below treeline is saturated and rapidly melting.
Spring is upon us and the snowpack can change drastically in a short time with solar or temperature input. This MIN report here provides a good summary of aspect and elevation-dependent conditions around the Whistler Backcountry on Saturday.
Problems
Wind Slabs
New snow through Monday may hide recently formed wind slabs in lee terrain near ridges above 2000m. As new snow accumulates with increasing winds, reactive deposits are expected to build through Monday.
- New cornices will be weak and could trigger wind slabs on slopes below.
- Be careful with wind-loaded pockets, especially near ridge crests.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
The likelihood of loose wet avalanches will depend on accumulating precipitation and a warming snowpack.
- Minimize overhead exposure and avoid steep slopes during periods of strong sun.
- Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 22nd, 2019 2:00PM
