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Parks Canada grant statham, Parks Canada

Banff Yoho & Kootenay National Park Avalanche Forecast

Apr 28th, 2019 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs, Loose Wet and Persistent Slabs.

Hard to believe we still have three main problems in the snowpack considering its the end of April. Heads up at higher elevations and keep your winter thinking cap on for a few more days this week.

Summary

Weather Forecast

Unsettled weather for the week ahead. Expect on again, off again snow showers with temperatures staying cool and the wind remaining out of the north.  These kinds of weather patterns can result in some locally deep accumulations, so pay close attention where you travel.

Snowpack Summary

Up to 40cm of snow fell by Sunday morning with more in eastern areas. Strong winds during the storm did some wind loading, but the storm ended calm and cold. While the new snow should settle rapidly, be suspicious of its bond to the old snow and any facets below. Supportive crusts exist below this new snow on solar aspects and at lower elevations.

Avalanche Summary

Some small storm slabs observed on Saturday. Skier controlled small storm slabs in alpine lee areas reported by the local ski areas during control work on Saturday. No new avalanche activity was observed or reported on Sunday.

Confidence

Problems

Storm Slabs

An icon showing Storm Slabs

Likelihood

Possible - Unlikely

Expected Size

1 - 2

40 cm of new snow from the storm and wind on Saturday is forming a slab over a variety of old wind slabs, crusts and facets in the alpine. The likelihood of avalanches is on the way down, but will  persist for a few more days.

  • Use caution in lee areas. Wind loading could create slabs.
  • The new snow will require several days to settle and stabilize.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely - Possible

Expected Size

1 - 1.5

Any short spells of sun will quickly moisten the surface snow and produce wet sluffs.

Aspects:

South East, South, South West, West.

Elevations:

Alpine, Treeline.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible - Unlikely

Expected Size

1 - 2

We have seen some evidence of lingering deeper instabilities in the alpine from various crust and facets layers in April. These have been triggered by cornice falls and wind slabs. Keep checking for these weaknesses in steep alpine features.

Aspects:

North, North East, East.

Elevations:

Alpine.

Valid until: Apr 29th, 2019 4:00PM