Regions
South Coast Inland.
Natural avalanche activity has tapered but wind slabs continue to be reactive to human triggering. Pay attention to overhead hazards like cornices, especially when the sun is out.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Friday
Weather Forecast
New snow amounts on Friday will vary through the region. The Coquihalla (southern areas) could see 5-15 cm of new snow, while the Duffy (northern areas) may only receive 3-8 cm of new snow. Thursday: Mostly sunny with alpine temperatures near -7 and freezing levels 500 m. Ridgetop winds moderate from the North.Friday: Overcast with new snow amounts 5-15 cm. Alpine temperatures near -5 and ridgetop wind strong from the southwest. Saturday: Mix of sun and cloud in the North and overcast in the South. Snow amounts 5-10 cm with less in the North. Alpine temperatures near -5 with freezing levels 600 m. Light to moderate winds from the West.
Avalanche Summary
On Tuesday, reports of several natural loose dry avalanches up to size 1 from steep south facing rocky terrain. Wind slabs are becoming more stubborn to human triggers but remain the primary avalanche concern for the region. Respect overhead hazards like cornices, especially if Thursday is sunny. A large trigger (like cornice fall) could initiate a large slab avalanche from the slope below.
Snowpack Summary
Extensive wind effect exists at treeline and above. In exposed terrain, strong north and east winds have scoured windward slopes and loaded lee slopes. You can still find low density snow from last Saturday's storm stashed in sheltered trees at treeline and below. The cold temperatures are promoting settlement and surface facetting in the recent storm snow. In southern parts of the region, the new snow (40-50 cm) sits above a widespread crust with well settled snow below the crust. In northern parts of the region up to 30 cm of recent storm snow exists. Avalanche professionals are still monitoring the mid-January crust and are avoiding shallow rocky slopes where triggering this layer is most likely. This layer is now 80-150 cm deep, but a heavy trigger (cornice?) or the next major storm (warming and loading) could potentially wake up this layer.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.