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Parks Canada jesse milner, Parks Canada

Jasper National Park Avalanche Forecast

May 10th, 2019 5:21PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Loose Wet, Persistent Slabs and Cornices.

Expect there not to be an overnight freeze well into the alpine for the next couple days. Rock climbing, mountain biking and water sports are an excellent choice as well.

Summary

Weather Forecast

Warm and convective with no overnight freezes.

Saturday: Sunny with cloudy periods. Alpine temps: Low 5, High 13. Light west winds. Freezing levels 3600m.

Sunday: Mostly cloudy with 2800m freezing levels and possible showers starting in the afternoon.

Monday: Cloudy with possible showers with up to 4mm Low 2, High 9. Freezing levels 3000m.

Snowpack Summary

Snowpack is becoming isothermal into the alpine on shady aspects. The snowpack has transitioned rapidly from Winter to a summer like snowpack. Little to no overnight freezes are expected.

Avalanche Summary

Since the warming trend there has been an avalanche cycle. Numerous loose wet avalanches up to size 2 have been observed in the alpine and treeline. Near Jasper townsite in shallow snowpack areas several large (size 3) slab avalanches have been observed on North to Easterly aspects in the alpine and running into valley bottoms.

Confidence

Freezing levels are uncertain

Problems

Loose Wet

Summer like temps have created an avalanche cycle. With no overnight freezes and more sunny days forecasted this problem will continue for the next while.

  • If triggered loose wet sluffs may step down to deeper layers resulting in larger avalanches.

Aspects:

All aspects.

Elevations:

All elevations.

Likelihood

Very Likely - Likely

Expected Size

1 - 2

Persistent Slabs

Weak mid-pack facets and upper-snowpack are reactive, especially on shaded, wind-sheltered slopes. This is a Wet Slab problem on solar aspects, as water accumulates above strong crusts.

  • If off-trail travel is deep and punchy, avoid all avalanche terrain, including runouts.
  • Minimize exposure to big slopes, especially during the heat of the day.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Likelihood

Likely - Possible

Expected Size

1.5 - 3

Cornices

Occasional cornice falls are expected, increasing into the weekend. some of these may trigger large slab avalanches, running well down into lower elevations.

  • Minimize exposure to overhead hazard from cornices.
  • Stay well to the windward side of corniced ridges.

Aspects:

North, North East, East, North West.

Elevations:

Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: May 11th, 2019 4:00PM