Avalanche Forecast

Issued: Feb 23rd, 2017 3:55PM

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

triley, Avalanche Canada

Lizard-Flathead.

Recent storm slabs may take another day to settle and bond to the old surface. Avoid slopes below cornices.

Summary

Confidence

High -

Weather Forecast

Tonight: Overcast with a chance of flurries, light southwest winds, and -15 in the alpine. Friday: Broken skies with periods of flurries, light westerly winds, and alpine temperature -15. Saturday: Mix of sun and cloud with moderate southwest winds and alpine temperatures -10. Sunday: Overcast with 3-5 cm of snow, light east winds and alpine temperatures -10.

Avalanche Summary

No new avalanches reported. There was a report on Tuesday of a natural avalanche size 3.5 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 of sugary facets near the ground. On Wednesday we had a report of a size 3.0 avalanche on "Big Steep Mother" bowl on a northeast aspect at 2100 metres in the alpine in the Lizard range. 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

There is now 50-60 cm of storm snow that is expected to settle into a storm slab. This slab sits above a thick rain crust below 1900 m and a generally well settled snowpack. Isolated basal weaknesses may still exist in shallow snowpack areas. These weak areas appear to be on north-northeast aspects in the alpine. If the winds shift direction over the next few days, watch for new wind loading on south-west aspects.

Problems

Storm Slabs

Deep storm slabs (50-60cm) may take some time to settle and bond to the old surface. This problem may linger in areas with a hard rain crust below the storm snow.

Minimize exposure during periods of heavy loading from new snow, wind.Use caution in lee areas. New snowfall mixed with wind loading will create slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Fresh cornice growth may be large and fragile. Cornice falls may release storm slabs, or step down to deeply buried weak layers resulting in large avalanches.

Extra caution needed around cornices with current conditions.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

There have been two natural deep persistent slab releases in the past few days in the Lizard range. Both of these avalanches were on northeast aspects in the alpine, and released to size 3.0 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

Expected Size

2 - 4

Valid until: Feb 24th, 2017 2:00PM