Banff Yoho & Kootenay National Park Avalanche Forecast

Issued: Apr 15th, 2021 4:44PM

Thu Apr 15th Current Conditions
Alpine Below Threshold Treeline Below Threshold Below Treeline Below Threshold
Fri Apr 16th 2 Day Outlook
Alpine Below Threshold Treeline Below Threshold Below Treeline Below Threshold
Sat Apr 17th 3 Day Outlook
Alpine Below Threshold Treeline Below Threshold Below Treeline Below Threshold

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

The crux of the big warmup approaches. We expect a good overnight freeze for Friday, but no freeze for Saturday morning. Be clear of all avalanche terrain by noon and do something else if the snow is not frozen. Saturday might be too warm and slushy.

Summary

Weather Forecast

The clear skies and warm, sunny weather will continue until Sunday, getting slightly warmer each day. Freezing levels are forecast to reach 3000 m on Friday and a poor freeze is expected on Friday overnight. Saturday could be "the day" for avalanches. The next few days is the biggest warmup to 3000 m so far this year.

Snowpack Summary

Hard surface crusts in the morning, then wet snow in the afternoon. High elevation north aspects will still hold dry snow. Another solid overnight freeze is expected for Friday morning, then deteriorating rapidly as the day warms up. There are several persistent layers n the mid to lower snowpack will wake up over the next 48 hr.

Avalanche Summary

Many loose snow avalanches up to size 2 were observed from the valley bottom on Thursday, running long distances in gullies. We had no observations after 2:00 pm, and expect the peak of avalanche activity to be later in the afternoon, so these observations are likely incomplete.

Confidence

Problems

Loose Wet

An icon showing Loose Wet

Likelihood

Very Likely

Expected Size

1 - 2.5

Expect widespread wet loose avalanches in all gullies on Friday and Saturday. Don't expose yourself to any gully features once the day begins to warm up.

  • Daytime warming will weaken surface layers, plan your day around being back to the trailhead early.

Aspects:

East, South East, South, South West, West.

Elevations:

All elevations.

Cornices

An icon showing Cornices

Likelihood

Very Likely

Expected Size

1.5 - 3

Cornices are huge and are failing consistently, sometimes triggering deeper layers in the snowpack. With the intense solar input forecasted, they may start to fail early in the day.

  • Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.
  • Give cornices a wide berth when traveling on ridges.

Aspects:

North, North East, East, South East, North West.

Elevations:

Alpine.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3

Be wary of large slab avalanches on Friday and Saturday as the heat penetrates deep into the snowpack and wakes up some old persistent weak layers. Do not expose yourself to any avalanche terrain after noon.

  • Pockets of persistent slabs linger on alpine lee features.
  • Pay attention to overhead hazards like cornices which could trigger persistent slabs.

Aspects:

All aspects.

Elevations:

Alpine.

Valid until: Apr 16th, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.