Avalanche Forecast

Issued: Apr 19th, 2014 8:01AM

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

catherine brown, Parks Canada

Glacier.

If the sun stays out this afternoon and the solar inputs are high, avalanche hazard will rise. Use caution in these conditions on and below sun effected terrain.

Summary

Weather Forecast

A break in the precipitation is forecast today with freezing levels possibly rising to 1800 m this afternoon and alpine temps around +4. The snow will return tonight as freezing levels fall to 1200 m with accumulations around 5-10 cm and moderate SW winds. Flurries stop on Sunday with a warm (freezing levels above 2000 m) and wet Monday forecast.

Snowpack Summary

10-15cm of HST at treeline (deeper in lee alpine terrain) is poorly bonded to a crust below. Over the last few days BTL has received moist snow with rain below 1300m. -6 at treeline overnight would have formed in a good surface crust. The snowpack on solar aspects is warming to near isothermal levels. There are a series of crusts in the top meter.

Avalanche Summary

Little natural avalanche activity was observed yesterday. On Thursday a small natural avalanche cycle occurred mid-day. Avalanches size 2-2.5 with moist deposit were observed east of the Rogers Pass and in the Connaught drainage. One of those avalanches was a glide crack release from 1650 m on a south aspect.

Confidence

Freezing levels are uncertain

Problems

Wind Slabs

New snow and moderate S/SW winds have formed wind slabs in exposed terrain in the last few days. Use caution on these firm pockets of wind deposited snow.

Use caution in lee areas. Recent wind loading have created wind slabs.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Moist new snow, mixed with rain, will bond poorly to the weak crust and nearly isothermal snow below. Sunny breaks will weaken the snowpack. Wind loading may trigger avalanches, becoming loose wet.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Temperature swings and solar inputs have weakened cornices. If these large triggers fail, they could trigger a big, high consequence avalanche.

Cornices become weak with daytime heating, so travel early on exposed slopes.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Apr 20th, 2014 8:00AM