Avalanche Forecast

Issued: Apr 28th, 2013 4:30PM

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

a.l. horton, Parks Canada

Jasper.

The stormy weather will continue on Monday. The avalanche danger will be highest on windloaded alpine slopes.

Summary

Weather Forecast

Another low will move through Sunday night bring more snow and moderate to strong Westerlies, leavingÂ cool unstable airÂ in its wake.Â A slow warming trend is expected to begin by mid-week, could it finally be spring?

Snowpack Summary

25-30 cm of moist storm snow is sitting on an isothermal snowpack at treeline.Â Storm slabs 30-50 cm thick are on sitting on the April 25th melt freeze crust in the alpine.Â Isothermal conditions below treeline that may have a weak melt freeze crust develop overnight.

Avalanche Summary

No avalanches observed on a patrol from Jasper to Saskatchewan Crossing with fair visibility

Confidence

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

Problems

Storm Slabs

25 cm of storm snow has fallen with another 15-20 expected. Strong Westerly winds have moved this snow onto lee aspects and suspect that thick slabs have developed on the old melt freeze crust. Bonding of these slabs to the crust is uncertain.

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 - Very Likely

Expected Size

1 - 3

Cornices

Plenty of fresh snow and strong Westerly winds will continue to build cornices and 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, South West.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Apr 29th, 2013 4:00PM