Avalanche Forecast Lizard Range and Flathead

Date Issued: Valid Until:

Avalanche Canada ghelgeson, Avalanche Canada

Avalanche Forecast

Mon Apr. 15th ยท 5:05PM

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low
Loose Wet Loose Wet
Storm Slabs Storm Slabs

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low
Winter is going out with a bang after producing 30 cm of storm snow Saturday night. Rising temperatures and the strong April sun are expected to produce a turbo charged loose wet avalanche cycle on Tuesday.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

A rather slack and warm pattern is setting up with the big story being the steadily rising freezing level. It doesn't look like we'll get any significant precipitation this week. MONDAY NIGHT: Freezing level around 500 m, light variable wind, no new snow expected. TUESDAY: Scattered cloud cover clearing to just a few clouds in the late afternoon, freezing level rising to around 2100 m, light variable wind, no significant snowfall expected. WEDNESDAY: Broken cloud cover, freezing level rising to around 2200 m, moderate to strong west wind, no significant snowfall expected. THURSDAY: Scattered cloud cover, freezing level rising to around 2800 m, moderate to strong west wind, no significant precipitation expected.

Avalanche Summary

On Sunday skier triggered avalanches were widespread on north through east facing slopes in the alpine and down into treeline too.A natural avalanche cycle occurred Saturday night, the highlights were storm slabs up to size 2 on northeast facing alpine terrain around 1700 m. A natural cornice failure was observed from a north facing ridgeline which subsequently triggered a size 2.5 storm slab involving the new snow. Control work produced storm slabs to size 2. We received a great MIN report of a small storm slab from Saturday morning, and this was well before the storm really kicked into gear.

Snowpack Summary

The Fernie Factor really kicked in late Saturday into early Sunday. The region picked up about 30 cm of snow (and 53 mm of water). Check out this great MIN report from Sunday. This snow sits above a widespread supportive crust. Steep, north facing, alpine terrain may still hold a cold, dry, snowpack where fresh storm slabs are thought to be widespread. Steep north facing terrain is also harboring a deeply buried layer of facets. Although unlikely, human triggering of persistent slabs on this layer may still be possible, especially in rocky alpine terrain with a shallow or highly variable depth snowpack. It looks like it is going to warm up this week and all the new snow will likely produce a widespread and powerful loose wet cycle. During the heat of the day, especially under direct sun, the snow surface will become moist or wet almost everywhere (except for high elevation north) and loose wet avalanches could run far.Below treeline the snowpack has melted or is isothermal.

Problems

Loose Wet

Loose Wet

Sunny breaks combined with fresh storm snow will likely turbo charge loose wet avalanche activity. The likelihood of loose avalanches increases as temperatures warm throughout the day and/or if the sun comes out for an extended period of time.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Loose avalanches may start small but they can grow large and destructive in these conditions.A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.

Aspects: East, South East, South, South West, West.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2
Storm Slabs

Storm Slabs

About 30 cm of storm snow rests on a widespread crust. The "crust free" exception may be high elevation north facing alpine terrain. Storm slabs likely remain sensitive to human triggering, especially in wind loaded terrain.

Recent new snow may be hiding windslabs that were easily visible before the snow fell.Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Possible

Expected Size

1 - 2