Regions
Northwest Coastal.
What might 70 km/h winds and rising temperatures do to the current snowpack!?
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Sunday: Mainly cloudy with snow expected later in the day. The freezing level is around 1000 m but could pop up to 1500 m near the coast. Ridge winds are moderate to strong from the S-SE. Monday: Periods of rain or snow. The freezing level could rise to 1800 m late in the day. Winds remain strong from the S-SE. Tuesday: Heavy rain or snow. The freezing level peaks near 2000 m and winds could be extreme from the S-SE.
Avalanche Summary
A couple fresh natural windslab avalanches were reported from an area northeast of Stewart on Friday. These slides were observed on west facing slopes near treeline, and were an average of 20 cm deep. Similar activity is possible throughout the region.
Snowpack Summary
Conditions vary significantly throughout the region. The common theme is that the snowpack is generally shallow, quite facetted (sugary), and very wind affected. A dusting of new snow now covers a mix of surface hoar or faceted snow in sheltered areas, and wind slab or ice crusts in exposed terrain. Strong E-SE winds have created dense new wind slabs in open north or west-facing terrain. Old hard wind slabs may also be lurking underneath. The mid-November crust-facet layer is now 40-60 cm deep and continues to show easy to moderate shears in snowpack tests. Deeper in the snowpack, at 80 cm down there is another crust that is breaking down and becoming bonded to the surrounding snow.
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.