Avalanche Forecast

Issued: Apr 4th, 2016 8:01AM

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

ian gale, Parks Canada

Glacier.

Rain this morning will destabilize the already weak snowpack. Avoid avalanche paths and steep openings below treeline where the snowpack is mushy & has lost its structure

Summary

Weather Forecast

Rain will start this morning, turning to snow this afternoon as freezing level drops. Possible snow amounts to 8cm with an Alpine high of 3 deg & southwest ridge wind @ 20kph gusting 45. Freezing level will spike to 2200m this AM then drop to 1300m tonight. Temps stay cool for the next couple of days however they go back up to 3600m by Thursday

Snowpack Summary

Warm temps and 3mm of rain yesterday have created an isothermal and moist snowpack. Thin surface crusts forming overnight are weak and break down quickly. Multiple crusts in the top meter of the snowpack provide sliding surfaces. Dry snow exists on steep N aspects in the high Alpine.

Avalanche Summary

Sunday there was a natural avalanche cycle in the park triggered by poor overnight freeze, daytime highs of +11, 3mm of rain and strong solar. Destructive wet avalanches were observed to size 3, the most notable were glide crack releases & low elevation slabs. Saturday night a south facing avalanche path on Cougar Mtn ran sz 3 to the end of runout.

Confidence

Freezing levels are uncertain

Problems

Loose Wet

Prolonged above 0 temps and 3mm of rain yesterday prevented the moist surface snow from refreezing. A treeline profile yesterday showed all temps were above zero & this AM's rain could rapidly destabilize the already weak snowpack.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Cornices

Very warm temperatures may weaken large cornices that exist along many ridges. New snow and moderate ridgetop winds will also add fresh growth. Cornice size & extent can is difficult to asses and should be done cautiously giving a wide margin.

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, South, South West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Persistent Slabs

Warm temps could wake up deeply buried weak layers. Recent tests on these crusts indicate that they will likely take a heavy trigger like a cornice fall or another avalanche, but if triggered very large avalanches are possible.

Use extra caution on slopes if the snow is moist or wet.Choose well supported terrain without convexities.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Apr 5th, 2016 8:00AM