Parks Canada jonas hoke, Parks Canada

Jasper National Park Avalanche Forecast

Apr 27th, 2019 4:00PM

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

A strong upslope storm has delivered heavy snowfall to the East and built windslabs in unusual places.

Summary

Weather Forecast

The low pressure center that drove Saturdays upslope moves into the prairies allowing cool air from the North East to establish itself over our area.

Sunday: Clear periods in the AM, with increasing cloud and flurries in the PM. Treeline temperature: Low -11 C, High -6 C. Ridge wind light northeast (gusting moderate). Freezing level: 1500 metres.

Snowpack Summary

A strong upslope has delivered over 30cm of snow in the front ranges, and up to 20cm in the Icefields region. This new snow is being reverse loaded by NE winds and will overly several crusts/facet layers in the upper snowpack. Windslabs can be expected on most aspects in the alpine. A faceted layer midpack on shady alpine aspects remains a concern.

Avalanche Summary

Poor visibility today, expect an avalanche cycle is ongoing with heavy loading from new snow and wind.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 2.5

Strong winds and heavy snowfall (heaviest in the front ranges) has built fresh slabs on most aspects.  Be particularly cautious on planar slopes where the new snow overlies a crust.

  • Keep an eye out for reverse loading created by N-NE winds.
  • Use caution in lee areas. Recent wind loading has created wind slabs.

Aspects:

All aspects.

Elevations:

All elevations.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

1.5 - 3

Loading from new snow has likely increased the sensitivity of this layer.

  • Watch for signs of instability such as recent avalanche activity, and whumpfing/cracking underfoot.
  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects:

North, North East, East, North West.

Elevations:

Alpine.

Valid until: Apr 28th, 2019 4:00PM