North Rockies Avalanche Forecast

Issued: Nov 24th, 2021 4:00PM

Thu Nov 25th Current Conditions
Alpine Considerable Treeline Considerable Below Treeline Low
Fri Nov 26th 2 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Low
Sat Nov 27th 3 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Low

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Storm Slabs.

More snow is on the way! Watch for dangerous conditions at higher elevations where heavy snowfall accumulations are expected. Stick to low angle terrain on Thursday.

Summary

Confidence

Moderate - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather. Uncertainty is due to the limited number of field observations.

Weather Forecast

A frontal system crossing the region on Wednesday night will bring 10-35 cm of snow, strong wind, and mild temperatures.

WEDNESDAY NIGHT: Heavy snow with 5-20 cm (heaviest accumulations along the western side of the range), strong southwest wind with gusts to 100 km/h, freezing level climbing to 1300 m overnight.

THURSDAY: Snow continues with another 5-15 cm throughout the day, strong southwest wind with gusts to 100 km/h, freezing level reaches 1500 m.

FRIDAY: Unsettled weather between storms with flurries bringing roughly 5 cm of snow, strong southwest wind with gusts to 60 km/h, freezing level drops to valley bottom with treeline temperatures around -5 C.

SATURDAY: The next front approaches with 5-10 cm of snow possible by the evening, strong southwest wind, and freezing level climbing to 1500 m.

Avalanche Summary

Over the past week there have been several reports of unstable storm slabs. While these instabilities have likely settled, the incoming weather will produce new storm and wind slab problems. 

There have been no reports of avalanches on persistent weak layers this season, although reports are limited, and we strongly encourage people to share observations on the Mountain Information Network

Snowpack Summary

A frontal system will bring 10-35 cm of new snow to the region by Thursday evening. The heaviest accumulations will likely be around Pine Pass, the McGregor range, and around McBride. Rising freezing levels will result in rain at lower elevations and heavy snow at upper elevations. The eastern side of the Rockies will receive less snow, but strong wind will likely form wind slabs in steep leeward terrain.

Recent observations suggest treeline snow depths are around 80-140 cm with very little snow below 1400-1600 m. A series of storms over the past few weeks delivered about 40-80 cm of snow, which sits above an early season crust(s). Reports indicate the snow has generally bonded well to the early season crusts. Exceptions may be shallow alpine slopes along the eastern side of the Rockies towards Jasper.

Terrain and Travel

  • Dial back your terrain choices if you are seeing more than 20 cm of new snow.
  • Avoid freshly wind loaded terrain features.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Remember that the snowpack will be significantly different at higher elevations than lower down.

Problems

Storm Slabs

An icon showing Storm Slabs

Likelihood

Likely

Expected Size

1 - 2.5

New snow will create unstable slabs at upper elevations on Thursday. In areas that get more than 20 cm of fresh snow these will be widespread on all steep slopes, while in areas that receive less snow they will more likely be isolated to wind-loaded slopes.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Nov 25th, 2021 4:00PM

Forecast Trend

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