Yukon Avalanche Forecast

Issued: Apr 14th, 2021 2:00PM

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

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

Expect a spike in avalanche activity on Friday with rapidly warming temperatures (read more in this Forecasters' Blog). Wind slabs may also remain reactive to human triggering.

Summary

Confidence

Moderate - Uncertainty is due to rapidly fluctuating freezing levels. Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

WEDNESDAY NIGHT: Partial clearing overnight, south wind 40-60 km/h easing to 30 km/h, treeline temperatures drop to -5 C. 

THURSDAY: Partly cloudy, 20 km/h south wind, freezing level climbing to 1500 m in the afternoon.

FRIDAY: Mix of sun and cloud, light south wind, freezing level climbing from 1500 to 2200 m.

SATURDAY: Mix of sun and cloud with some isolated flurries, light northeast wind, freezing level around 1500 m.

Avalanche Summary

With the incoming warming trend expect avalanche activity to transition from wind slab to wet loose activity. Weather forecasts suggest the greatest warming impacts will be on Friday. Keep in mind periods of rapid warming can increase the likelihood of large natural avalanches.

There were a few reports of small wet loose avalanches at low elevations on Tuesday and numerous reports of reactive wind slab avalanches between Friday and Monday (with multiple size 1-2 avalanches running on a 30-70 cm deep crust layer).

Snowpack Summary

Warming temperatures over the next few days will form moist surfaces at lower elevations and on sun-exposed slopes (if the clouds break up). 15-30 cm of wind-affected snow overlies a hard crust found up to 1300 m. The wind effect is particularly widespread along the highway corridor at White Pass but may be less so as you push into the side valleys.

While there have not been many weak layers of concern this season, there is some uncertainty about whether the big warm up on Friday will increase the reactivity of any deeper layers. This will more likely be an issue in shallow snowpack areas like the Wheaton compared to the thicker and stronger snowpack around White Pass.

Terrain and Travel

  • Extra caution for areas experiencing rapidly warming temperatures for the first time.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • Be aware of the potential for large avalanches due to the presence of a buried crust.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.

Problems

Loose Wet

An icon showing Loose Wet

Likelihood

Likely-Very Likely

Expected Size

1 - 2

Spiking freezing levels will destabilize surface snow and result in natural wet loose avalanches, especially on Friday.

Warming could also possibly initiate slab activity in shallow snowpack areas like the Wheaton Valley.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

Wind slabs above a crust layer have been reactive to human triggering over the past week. Looking forward they may still be possible to trigger in steep open terrain.

Aspects:

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

Elevations:

Alpine, Treeline.

Valid until: Apr 16th, 2021 2:00PM

Forecast Trend

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