Avalanche Forecast

Issued: Mar 24th, 2013 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Deep Persistent Slabs and Cornices.

garth lemke, Parks Canada

Jasper.

Good overnight freeze is occurring; however, the sun packs a punch. The danger will increase in the afternoons at all elevations particularly on South aspects, gullies, and sun affected bowls. Gauge the amount of overnight freeze to start your day.

Summary

Weather Forecast

Monday to Wednesday will be clear skies, strong diurnal temperature fluctuation, and light W to NW winds. Freezing level is incrementally increasing each day this week. Monday it will be 1700m, Tuesday 1800m, and clouds on Tuesday evening may prevent a good overnight freeze starting the day off warm for Wednesday.

Snowpack Summary

A variable thick slab exists in alpine and treeline locations on a variety of aspects. It is over a strong midpack except in shallow locations where you could trigger basal facets or depth hoar weakness at the ground. At treeline in south facing terrain, their is a suncrust 80 cm deep. Strong diurnal temperature fluctuations have helped stability.

Avalanche Summary

No Sunday patrol. Nothing new noted on Saturday's Icefield's patrol with good visibility. A size 3 noted on Friday off Indian ridge main peak up Whistler creek scrubbing to ground, cornice fall trigger, and ran far. Thursday in Shangrila a size 3 was triggered by cornice fall in the afternoon heat, scrubbed to ground, 2m crown, and ran full path.

Confidence

Freezing levels are uncertain

Problems

Deep Persistent Slabs

The March 13 90cm of snow has melded with the snowpack making for a deep persistent slab. North and South winds make it present on a variety of aspects overlying weak basal facets. Cornice failures can trigger this in a big way.

Choose the deepest and strongest snowpack areas on your run.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Cornices

Cornices will become increasingly prone to failure as the days get warmer. They are a hazard in themselves plus their failure is a large trigger which may initiate large avalanches potentially running full path. Watch what's overhead.

Pay attention to overhead hazards like cornices.Extra caution needed around cornices with current conditions.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Mar 25th, 2013 4:00PM