Avalanche Forecast

Issued: Jan 23rd, 2021 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada cmortenson, Avalanche Canada

Forecast 5-15 cm of new snow will improve riding conditions. However, be careful of reactive wind slabs in the immediate lee of windy ridge crests - especially if surface hoar is suspected. If new snow fall deposits exceed 20cm, carefully asses the bond of new snow.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

A weak front crossing the region brings clouds, moderate winds and light snow Saturday night into Sunday followed by clearing early in the week.

SATURDAY NIGHT: Cloudy with scattered snow flurries and 5 to 15 cm snow, moderate to strong southwest wind, treeline temperatures around -8 C. A mild alpine temperature inversion weakens overnight. 

SUNDAY: Cloudy with scattered flurries and 2-10 cm of snow, moderate northwest wind, treeline temperatures rising to around -4 C. Freezing level 700 m.  

MONDAY: Mix of sun and cloud, light wind, treeline temperatures around -8 C.

TUESDAY: Mix of sun and cloud, light to moderate southeast wind, treeline temperatures around -10 C.

Avalanche Summary

No significant avalanche activity has been reported since Tuesday. In the week leading up to Tuesday there were several widespread natural avalanche cycles with size 1-3 storm slabs in the south of the region (see some photos in MIN reports here and here) and some very large size 3-4 deep persistent slab avalanches in the north.

The snowpack is rapidly gaining strength and wind slabs along windy ridge crests are the primary concern now. Be on the look out for fresh wind slabs from Saturday night's southwest winds and fresh snow in addition to buried deeper wind slabs from last week's wind. If you are travelling to northern parts of the region (e.g. Stewart or Ningunsaw), then persistent slabs should be on your radar as well.

Snowpack Summary

Forecast snowfall amounts of 5-15 cm on Saturday night will be redistributed by moderate to strong southwest winds in immediate lee of wind affected ridge crests treeline and above. This new snow will bury surface hoar and soft faceted surfaces from recent clear period as well as older wind slabs and wind affect from previous strong west winds. A shallowly buried crust exists below 1000 m. A total of 100-150 cm of settled snow has fallen in January, which has helped strengthen early season weak layers. Deeper layers appear to have gone inactive in the southern part of the region. However in the northern part of the region (e.g. Bear Pass, Ningunsaw) there has still been regular avalanche activity on weak snow at the bottom of the snowpack.

Terrain and Travel

  • Wind slabs are most reactive during their formation.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Make observations and assess conditions continually as you travel.

Problems

Wind Slabs

An icon showing Wind Slabs

Forecast 5-15cm of snow with moderate to strong southwest winds may form reactive wind slabs in immediate lee of ridge crests at treeline and in the alpine. Newly formed wind slabs will be particularly reactive where they sit atop buried surface hoar. Buried hard wind slabs may also linger on steep alpine slopes and along immediate lee of ridge tops from last week's winds.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Jan 24th, 2021 4:00PM