Avalanche Forecast

Issued: Feb 26th, 2017 4:13PM

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

ghelgeson, Avalanche Canada

Lizard-Flathead.

While wind sheltered features should offer great riding, be very cautious if you poke out into wind exposed terrain. Fresh sensitive wind slabs are expected to form as winds pick up over the next few days.

Summary

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

Light snowfall, cool temperatures and moderate westerly winds are expected for the first half of the workweek. There is potential for a significant warm up on Thursday. Stay tuned for details.MONDAY: Scattered cloud cover, freezing level at valley bottom, light to moderate west/southwest wind, isolated snow flurries, 1 to 5 cm possible. TUESDAY: Scattered cloud cover, freezing level at valley bottom, light to moderate west wind, 2 to 10 cm of snow possible.WEDNESDAY: Scattered cloud cover, freezing level at valley bottom, strong to extreme west winds, isolated snow flurries, 1 to 5 cm possible.Visit avalanche.ca/weather for a more detailed mountain weather forecast.

Avalanche Summary

On Saturday control work produced a few wind slabs from size 1.5 to size 2 in north facing terrain. Cornice avalanches to size 1.5 were also triggered by control work on north through northeast facing terrain. On Friday explosive control near Fernie resulted in a deep persistent avalanche; this avalanche was size 2.5 on a north aspect at 2000 metres, and is believed to have released on the mid-December facets. There was a report from last 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. Last 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

20 to 40 cm of cold, light density storm snow fell Saturday night. At this time, observations show very little wind activity. However, it won't take much more than a breeze to form wind slabs in exposed terrain over the next few days. This recent storm snow rests on an older wind/storm slab formed last week that is approximately 50 to 60 cm in depth which may still be sensitive to human triggering. This older 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.

Problems

Storm Slabs

20 to 40 cm of recent light density storm snow rests on top of an old storm/wind slab 50 to 60 cm in depth that may still be sensitive to human triggering, especially in steep terrain. Once the wind picks up, touchy wind slabs will be easily formed.

Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.Be very cautious as you transition from sheltered to wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

There have been two natural deep persistent slab releases in the past week 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 27th, 2017 2:00PM