Avalanche Forecast

Issued: Mar 27th, 2018 5:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Cornices.

cgarritty, Avalanche Canada

Lizard-Flathead.

Watch for bouts of sunshine to destabilize the new snow. Natural cornice falls triggering slabs have been a regular occurrence recently.

Summary

Confidence

High -

Weather Forecast

Wednesday: A mix of sun and cloud. Moderate west winds. Freezing level to 1500 metres with alpine high temperatures around -4.Thursday: A mix of sun and cloud. Light west winds. Freezing level to 1600 metres with alpine high temperatures around -3.Friday: Mainly cloudy with isolated flurries and a trace of new snow.Moderate to strong west winds. Freezing level to 1300 metres with alpine high temperatures around -3.

Avalanche Summary

Three more natural cornice releases were observed triggering size 2 storm slabs in the Fernie area on Monday.Reports from Sunday included numerous observations of recent large (size 2-2.5) natural storm slab releases in the Fernie area. Another round of explosives control yielded similar results, with slab depths generally from 30-70 cm. All but southwest aspects showed activity above 1800 metres and northeast aspects were the most active. Two natural cornice releases were also observed triggering slabs on the slopes they landed on.Cornice control on Saturday work gave numerous size 1-2 avalanches on north through southeast ridgelines. above 1900m. The cornice failures produced mostly loose dry avalanches from the slopes below with a few smaller slabs only releasing in the storm snow. On Friday, numerous natural storm slab avalanches were reported from north aspects above 1700 m.

Snowpack Summary

Up to 50 cm of recent storm snow has been showing a poor bond to the old snow surfaces it has buried, including a melt-freeze crust on sunny aspects and all aspects below 1600 m as well as surface hoar on north aspects above 1600 m. Wind slabs are building on most aspects due to the changing winds and overhanging cornices exist along ridgelines. Natural cornice falls triggering large avalanches has been a trend for the past few days.Deeper in the snowpack, the mid-December and late-November weak layers are composed of crusts and sugary facets, which are down 150-300 cm. These layers are currently considered dormant.

Problems

Wind Slabs

Strong southwest winds have redistributed our storm snow into reactive wind slabs in wind-affected areas at all elevations. Slabs may also be reactive in steeper, sheltered areas where the recent snow sits on crust or surface hoar.

Use extra caution on slopes if snow becomes moist or wet with sun exposure.Use ridges or ribs to avoid pockets of wind loaded snow.Wind slabs may be more reactive where they sit on a buried crust or surface hoar interface

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Cornices

Large looming cornices exist across ridgelines. Cornices are unpredictable and demand respect. They're more likely to fail during wind events or when the sun comes out. Natural cornice falls have recently been observed triggering slab avalanches.

Give cornices a wide berth when travelling on or below ridges.Pay attention to overhead hazards like cornices which could trigger slabs on slopes below.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Mar 28th, 2018 2:00PM