Avalanche Forecast

Issued: Mar 1st, 2017 5:08PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Deep Persistent Slabs.

swerner, Avalanche Canada

Lizard-Flathead.

Up to a metre of storm snow has fallen since Saturday and the incoming warm front will bring rising temperatures and strong winds. The perfect recipe for a widespread avalanche cycle.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

A warm front of an organized low pressure system will track across the region bringing rising freezing levels, more snow and strong winds. Conditions will remain unsettled through the forecast period. Enhanced snow amounts may be greater than forecast for Saturday/ Sunday.Thursday: Cloudy with snow 5-15 cm. Ridgetop winds strong from the SW, alpine temperatures near -3 and freezing levels 1200 m.Friday: Periods of snow 5-20 cm. Ridgetop winds light gusting to 80 km/hr from the SW, alpine high of -3 and freezing levels 1300 m.Saturday: Snow 5-10 cm. Ridgetop winds generally light with strong gusts. Alpine temperatures high of -2 and freezing levels 1300 m.

Avalanche Summary

On Wednesday, the region saw widespread natural and explosive controlled avalanche activity up to size 2. These avalanches failed within the recent storm snow mostly from N-NE aspects above 1950 m. Natural Loose dry avalanches up to size 1.5 were also reported from all aspects and elevations.

Snowpack Summary

Another 36 cm overnight of low density storm snow with accumulations up to 93 cm since Saturday. Strong ridgetop winds are likely transporting the new snow onto leeward slopes, building thicker and stiffer slabs. This new snow continues to bury a plethora of old snow surfaces including surface hoar, old wind slab and a sun crust on solar aspects and it also sits above a thick rain crust below 1900 m. Isolated basal weaknesses may still exist in shallow snowpack areas. These weak areas appear to be on north-northeast aspects in the alpine.

Problems

Storm Slabs

Reactive storm slabs continue to build and are primed for rider triggering. Looming cornices exist and failures could initiate slabs on the slope below.

Avoid leeward slopes as thicker, reactive slabs will likely exist.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Deep Persistent Slabs

There have been two natural deep persistent slab releases in the past week. Both of these avalanches were on northeast aspects in the alpine, and released to size 3 or larger.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Be aware of the potential for large, deep avalanches.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Mar 2nd, 2017 2:00PM