Avalanche Forecast

High - Uncertainty is due to the timing, track, & intensity of the incoming weather system. Uncertainty is due to whether buried persistent weak layers become active, triggering avalanches, with the arrival of the forecast weather.

A storm system off the BC coast will continue to pump moisture into the region on southwesterly winds.

SUNDAY Night: Around 10 cm more snow overnight with favoured areas getting 15 cm. Moderate southwest wind. Temps remaining warm with the zero degree elevation around 1000m, around -5 C at treeline.

MONDAY: Continued snow with another 15 to 25 cm expected Continued moderate southerly winds. Continued warm temperatures between 0 C and -5 C near treeline. 

TUESDAY: More snow, 10 to 15 cm. More moderate SW wind. More temperatures at treeline just a few degrees below zero.

WEDNESDAY: The weather pattern changes as the wind shifts toward the northwest, temperatures cool, and the air dries out.

On Friday & Saturday avalanche activity was primarily small dry loose avalanches (sluffs) or small storm slabs. Two reports from the Monashees NW of Revelstoke are illustrative: this MIN from the 30th and this MIN from the 29th.

Initial reports from Sunday are of Storm Slab avalanches running within and at the bottom of the new snow.

Combining previous reports (e.g. those linked above running on surface hoar) with forecast snow fall amounts suggest an active natural cycle with increasing fracture depth and avalanche size. With poor visibility and people riding near treeline my spotlight is aimed at those surface hoar layers where avalanches could be deeper, wider, and run further than expected.

We're in a period of continued snowfall. With 10 to 30 cm today the storm snow totals are approaching 40 to 60 cm and more is forecast. With another 20 to 40 on the ground by Monday night or Tuesday morning some areas could approach the 100cm milestone! Moderate to strong southerly winds will build windslabs. Temperatures are warming so the coldest (lightest, least cohesive) snow is at the bottom, warmer (cohesive, slabby) snow is above. 

The storm snow rests on the January drought layer: surface facets (sugary granules), surface hoar, wind hardened and sun crusts, etc.)

Observers continue to find a deeper preserved layer of surface hoar from earlier in January down 40-80 cm in sheltered, open slopes near treeline. Recent tests with sudden results suggests a need for continued assessment. Honestly, this storm is going to test the mid-January Surface Hoar layer (which I'm introducing as a new Avalanche problem). 

The mid and lower snowpack is generally strong. Prolonged periods with no avalanche activity and unreactive snowpack tests results show the November & December layers (crust & facets) are dormant. 

• Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
• Storm slab size and sensitivity to triggering will likely increase through the day.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.