Avalanche Forecast

Issued: Apr 6th, 2016 8:00AM

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

chris gooliaff, Parks Canada

Glacier.

35cm of storm snow with strong southerly winds are building storm slabs in the alpine. Winter is here for another 24 hours.

Summary

Weather Forecast

Mainly cloudy today with isolated flurries, especially west of Rogers Pass. Freezing level will hover around 2000m with moderate to strong winds from the SW. Tonight will see a general clearing trend with freezing levels staying near 1900m. Tomorrow will see a heat wave roll through, with sunshine and freezing levels rising to 3700m.

Snowpack Summary

The west side of the Pass received up to 20cm last night, bringing the 2 day total to 35cm. East of the Pass received much less. Storm slabs are building with the mod/strong southerly winds in lee areas, more prevalent above 2400m where the snow is cooler. New snow is insulating a warm, moist snowpack, and multiple crusts exist in the upper metre.

Avalanche Summary

Very little activity was noted yesterday. Isolated avalanches to size 2.5 were observed from very steep, N-facing start zones on Mt Macdonald and Ross Peak, travelling as far as the top of the avalanche fan. A field team at the Illecillewaet Glacier toe noted 15-20cm of dry surface snow with over 50cm of weak, moist snow below.

Confidence

Problems

Storm Slabs

Strong southerly winds continue to redistribute the new snow into lee features, especially in the high alpine where temp's are a little cooler. At higher elevations, these slabs will be touchier than lower down.

Be cautious as you transition into wind affected terrain.Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Lower elevation tests show an isothermal snowpack. The new snow is acting like insulation and is preventing a solid overnight refreeze. If loose slides are triggered, they have the potential to entrain a lot of mass and be destructive.

Be alert to conditions that change with elevation.Use extra caution on solar slopes or if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Persistent Slabs

Step-down avalanche potential exists with the many crusts buried in the upper metre, especially on solar aspects. It will take a heavy load to trigger them, like a cornice fall or another avalanche. Expect large avalanches if they move!

Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Apr 7th, 2016 8:00AM