Avalanche Forecast

Issued: Apr 27th, 2013 4:00PM

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

a.l. horton, Parks Canada

Jasper.

Unsettled stormy weather will continue through the weekend. Travelers in avalanche terrain will need to have good skills to assess the changing conditions.

Summary

Weather Forecast

A continuous series of low pressure systems are expected to move through the area until Monday.Â With each passing front, expect strong westerly winds, light to moderate precipitation and noticeable rising and falling of the freezing level from the surface to 2200 m.Â More stable conditions are expected by Tuesday.Â

Snowpack Summary

Cool overnight temperatures may create a week melt freeze crust at treeline and below treeline that will likely loose strength by mid-day Sunday.Â Strong NW winds have been building windslab with the 15 to 20 cm of new snow on SE aspects in the alpine.

Avalanche Summary

Poor visibility prevented alpine avalanche observations on Saturday.Â Several wet slab avalanches to size 1.5 were observed below treeline on steep rocky terrain.Â These avalanches were triggered by light to moderate rain on a warm snowpack.

Confidence

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

Problems

Wind Slabs

Strong to extreme NW winds 15 to 20 cm of new snow have created windslabs on lee slopes. South facing slopes should be approached cautiously where buried sun crusts may provide the perfect failure plane.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

A strong overnight freeze is not likely and warm temperatures Sunday afternoon will reactive the chance of loose wet avalanche occurring on steep terrain features.

Start and finish early before the surface crusts melt.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Fresh snow and strong North Westerly winds will increase the likelihood of cornice failure. Deep releases from a wet snowpack may run far into the valley bottom.

Extra caution needed around cornices with current conditions.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Apr 28th, 2013 4:00PM