Avalanche Forecast
Regions: South Columbia.
Rain/snow and strong winds may initiate a loose wet avalanche cycle at treeline and form fresh storm slabs reactive to human triggers in the alpine.
Confidence
Moderate - Freezing levels are uncertain
Weather Forecast
THURSDAY NIGHT: Rain (snow above roughly 2300 m.); 10-20 mm / Strong, southwesterly winds / Alpine low 3 C / Freezing level 2500 m.
FRIDAY: Rain (snow above roughly 2100 m.); 10-15 mm / Strong, southwesterly winds / Alpine high 3 C / Freezing level 2300 m.
SATURDAY: Sunny / Light, northwesterly winds / Alpine high 3 C / Freezing level 2100 m.
SUNDAY: Sunny / Light, northwesterly winds / Alpine high 5 C / Freezing level 2300 m.
Avalanche Summary
On Wednesday, explosive control work near Revelstoke produce numerous loose wet avalanches up to size 1.5. Avalanche activity is expected to increase on Friday with the forecast rain/alpine snow and strong winds.
On Tuesday, two naturally triggered size 1.5 storm slab avalanches 25 cm deep were reported on northwest aspects 2200-2400 m.
Several recent natural slab avalanches up to size 2 have been reported on north and east aspects in the alpine. The suspected weak layer was either a crust or small surface hoar that was down 25-50 cm.
Snowpack Summary
5-10 mm. rain (snow above roughly 1900 m.) on Thursday is adding to the 20-40 cm recent snow which overlies a crust everywhere except high elevation, north facing terrain where preserved surface hoar (weak, feathery crystals) may be present in isolated locations. A similar layer buried in early April is down 40-50 cm. Smaller storm slab avalanches may step down to one of these deeper weak layers.
Below treeline, snow is disappearing rapidly.
Avalanche Problems
Storm Slabs
Additional snow, wind, and warm temperatures on Thursday night may form fresh storm slabs reactive to human triggers in the alpine.
- Minimize overhead exposure during periods of heavy loading from rain/snow and wind.
- Pay attention to changing conditions with elevation/aspect.
- Use small slopes without consequence to test the bond of the recent snow.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Likely
Expected Size: 1 - 2.5
Loose Wet
Forecast rain to roughly 2100-2300 m. may initiate a loose wet avalanche cycle.
- Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.
- A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.
- Minimize overhead exposure during periods of heavy loading from rain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2