Avalanche Forecast

Wind slab avalanches size 1-2 were observed prior to the weekend on north to east facing slopes in the alpine. Some of them are suspected to have been triggered by cornice falls.

Recent snowpack test results and signs of instability like shooting cracks reported in recent MINs also suggest instability in wind slabs.

Variable snow conditions exist at upper elevations due to extensive wind affect by sustained moderate west to northwest winds. Soft snow can still be found in sheltered areas like in trees, gullies and bowls.

A widespread near-surface crust has been described in nearly every MIN report this week (thank you!). It sits on the surface in scoured, windward features; an average of 10 cm deep in sheltered areas; and up to 30 cm deep in wind-loaded areas. Some faceting has been observed above the crust which has created a weak layer for overlying wind slabs to fail.

The snow below is a mix of dense wind affected snow layers at higher elevations. At lower elevations you may find another thin melt freeze crust 50+ cm deep. The lower snowpack is likely dense and well bonded from warm temperatures, rainfall and subsequent refreezing.

Saturday night

Flurries bringing a few cm of new snow. Moderate to strong northwest wind. Alpine temperature -10 to -15 C.

Sunday

3-8 cm of new snow. Moderate to strong northwest wind, switching northeast later in the day. Temperatures warming through the day, possibly reaching 0 C by evening.

A "backdoor warm front" pattern associated with a series of atypically tracking low pressure centers moving west-to-east is casting great uncertainty on the weather forecast beyond the weekend. The following outlook is from the 12Z RDPS model run but large variations from one run to the next give us low confidence. Generally, this pattern will likely bring strong easterly to northeasterly wind, warm air and the possibility of mixed precipitation.

Monday

A mix of sun and cloud. Moderate to strong easterly wind. Alpine temperatures dipping back below zero to around -5 C.

Tuesday

Increasing cloud with a possibility of mixed flurries. Strong northeast wind. Alpine temperature around 0 C.

More details can be found in the Mountain Weather Forecast.

• Seek out sheltered terrain where new snow hasn't been wind-affected.
• Expect slab conditions to change drastically as you move into wind exposed terrain.
• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Approach lee and cross-loaded slopes with caution.
• Wind slabs may be poorly bonded to the underlying crust.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
• The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
• Avoid steep slopes when air temperatures are warm, it is raining, or solar radiation is strong.