Avalanche Forecast

Issued: Feb 28th, 2017 6:56PM

The alpine rating is considerable, 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.

Updated at 9 AM!! Another 40 cm of storm snow overnight. Reactive storm slabs and loose dry avalanches are widespread up to size 2. Increased winds may drive the alpine into HIGH danger.

Summary

Confidence

High -

Weather Forecast

Wednesday: Snow accumulations 5-10 cm with moderate-strong SW winds. Alpine temperatures high of -4.Wednesday night-Thursday: Snow 5-10 cm with strong SW winds. Alpine high of -3 and freezing levels 1100 m. Friday: Snow amounts near 10 cm and moderate ridgetop winds from the SW. Freezing levels rising to 1400 m.

Avalanche Summary

Overnight, new storm snow and winds are causing widespread natural slab avalanches in the Lizard Range.Last week saw several notable deep persistent avalanches including explosive control near Fernie, this avalanche was size 2.5 on a north aspect at 2000 metres, and is believed to have released on the mid-December facets. Last Tuesday a natural avalanche size 3.5 occurred on Mt Hosmer on an East aspect at 2100 metres that appears to have released on, or stepped down to the weak deep persistent layer near the ground. Last Wednesday a size 3.0 avalanche was reported on "Big Steep Mother" bowl on a northeast aspect at 2100 metres. This avalanche appears to have been started by a cornice fall that released a storm slab that then "stepped down" to deeply buried weak facets.

Snowpack Summary

Another 40 cm overnight!! Since Saturday a total of 93 cm of cold, light density storm snow has fallen with little wind effect. This new snow has buried a plethora of old snow surfaces including surface hoar, old wind slab and a sun crust on solar aspects. This new snow also sits on a thick rain crust below 1900 m and a generally well settled snowpack. Isolated basal weaknesses may still exist in shallow snowpack areas. Smaller avalanches may have the potential to step down to those weaker layers waking up the deep persistent slab problem. These weak areas appear to be on north-northeast aspects in the alpine.

Problems

Storm Slabs

Another 40 cm of storm snow overnight building reactive slabs and loose dry avalanches. Looming cornices exist and failures could initiate slabs from the slope below.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

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.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Mar 1st, 2017 2:00PM