Avalanche Forecast

Issued: Mar 11th, 2013 4:38PM

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

conrad janzen, Parks Canada

Waterton Lakes.

10cm of new snow today and good skiing on N aspects! With the forecast snow, warm temps and strong SW winds the avalanche hazard will rise rapidly over the next two days. Stick to conservative terrain, and watch for overhead hazard!

Summary

Weather Forecast

Tuesday - Winds shifting to Strong out of the SW, freezing levels rising to 1800m and up to 25mm of precipitation! Wednesday - Strong SW winds, warm overnight with freezing levels up to 2000m and an additional 5mm of precipitation. Thursday - Strong SW winds, warm overnight with freezing levels to 2300m and an additional 5mm of precipitation

Snowpack Summary

10cm of new snow overlies sun crust on solar aspects, and thin wind slabs in isolated areas near ridge crests. Surface snow sluffs easily in steep terrain up to size 1. In thinner snow pack areas facets are present in the lower snowpack and may be a concern with rapid loading or warm temperatures.

Avalanche Summary

Surface snow sluffing out of steep terrain today up to size 1.5. The last several days have seen numerous loose wet avalanches on steep solar aspects up to size 2, and loose dry avalanches on steep N aspects up to size 2. With sun and warm temperatures a couple of cornices have triggered slabs out of extreme terrain in the last week.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Wind Slabs

With warm temperatures, new snow and strong SW winds we expect to see wind slab and cornice development at tree line and above over the next few days. These will be on a variety of crusts and storm snow interfaces and susceptible to skier triggering

Be cautious as you transition into wind affected terrain.Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Storm Slabs

With the forecast precipitation amounts, warm temperatures and strong SW winds you can expect natural and skier triggered storm slabs over the next few days on all aspects. Lower elevations may also see moist or wet snow avalanches!

Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Dry

With more snow the potential for loose dry avalanches in steep terrain will increase. Manage your sluffs carefully especially in confined terrain. With warming temperatures these may quickly turn into more serious storm slabs.

On steep slopes, pull over periodically or cut into a new line to manage sluffing.Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 14th, 2013 4:00PM