Avalanche Forecast

Issued: Feb 16th, 2018 4:00PM

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

landon shepherd, Parks Canada

Jasper.

Persistent midpack weaknesses are more pronounced in the northern portion of the forecast zone, with human triggering more likely than the Icefields area.

Summary

Weather Forecast

Flurries are expected overnight but with little accumulation resulting as a cold arctic front starts to sweep SW from the icy NE. Clearing expected Sunday and into next week with sunshine and cold nights.

Snowpack Summary

Available snow has been redistributed by strong, variable direction winds. In sheltered Treeline locations, the weak midpack layers are reactive down 50cm. Where snow remains in the Alpine, new wind slabs are reactive to triggering from additional load or solar, and wind-stiffened snow at Treeline is transmitting collapses large distances.

Avalanche Summary

Isolated windslab avalanches were observed today in the Icefields area and loose dry avalanches to size 2 were observed in the Tonquin valley. East, South, and North aspects have formed windslabs and large cornices that have failed in the last 48 hrs in the north portion of the forecast zone.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Variable direction, strong upper elevation winds are continuing to create fresh windslabs and stiffen the snow surface well into Treeline locations.

Variable winds have created pockets of wind slab on all aspects.The best powder will be found in sheltered locations at or below treeline.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Persistent Slabs

Whumpfing and cracking are signs of this layer's reactivity. Expect collapses to propagate larger distances with a wind-stiffened snow surface.

Watch for whumpfing, hollow sounds, and shooting cracks.Watch for surface cracking and stiffer surface layers of snow.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

Persistent slabs remain a problem. Areas exposed to large triggers such as cornices or smaller avalanches / sloughing from above are most likely to trigger this midpack weakness.

Pay attention to overhead hazards like cornices which could easily trigger deep slabs.Be wary of slopes that did not previously avalanche

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Feb 17th, 2018 4:00PM