Avalanche Forecast Little Yoho

Date Issued: Valid Until:

Parks Canada william lawson, Parks Canada

Avalanche Forecast

Tue Apr. 30th ยท 4:00PM

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low
Persistent Slabs Persistent Slabs
Wind Slabs Wind Slabs

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low

Although we are well into spring, persistent problems continue to plague the snowpack. Tuesday we observed two large avalanches on this layer.

Weather Forecast

Daily convective buildup is forecasted for the remainder of the week. Morning will likely have more stable weather and as the day progresses expect to see small storm cells roll through bringing wind and precipe. We should see a warming trend into the weekend with valley temps reaching plus ten by Friday.

Snowpack Summary

Up to 40cm of snow fell over the weekend at higher elevations. Strong winds during the storm have redistributed much of new snow at higher elevations. Cooler temps have promoted faceting in the upper snowpack creating a persistent interface where the new snow overlays previous crusts. Be cautious in areas where newly form slab overlays a crust.

Avalanche Summary

Our field team today observed two large avalanches (size2/2.5) in the Observation Peak area. Both avalanches released from south west aspects in the alpine. The slabs where remotely triggered by skiers and initiated on the persistent problem. Although no other avalanches were observed today, the persistent problem was certainly active in this area.

Confidence

Problems

Persistent Slabs

Persistent Slabs

This instability continues to rear its ugly head in areas where a slab sits over previously formed crusts. Though not widespread, where this layer dose exist expect it to be reactive. Tuesday we observed to large avalanches fail on this layer.

  • Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely - Possible

Expected Size

1 - 2.5
Wind Slabs

Wind Slabs

Up to 40 cm from the weekends storm coupled with strong to moderate wind has formed 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.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Unlikely

Expected Size

1 - 2