Regions
Northwest Inland.
Localized solar radiation, snow amounts and wind values may be higher than forecast. Use a conservative approach and watch for signs of instabilities like natural avalanche activity.
Confidence
Fair - Due to the number of field observations
Weather Forecast
Winter continues in the North as another intense storm moves onto the coast tonight resulting in very strong winds and light precipitation amounts. Very unstable air will result in unsettled conditions on Tuesday where localized light-moderate precipitation is possible ( 5-15 mm) accompanied by strong west winds and freezing levels near 1200 m. On Wednesday, precipitation amounts could see up to another 10 mm, freezing levels and winds consistent with Tuesday. There will be a lull in the weather pattern Thursday before things redevelop on Friday as another storm tracks across northern BC.
Avalanche Summary
No reports of natural avalanche activity yesterday. With continued precipitation, localized solar radiation and strong winds new storm slabs and winds slabs will likely be touchy on Tuesday. Natural and human triggered avalanches up to size 2 are expected.
Snowpack Summary
What new snow we have received has been blown into wind slabs on exposed lee slopes. The main concerns right now are wind slabs over a variety of surfaces that include crusts, facets and surface hoar that formed in in sheltered places during the last spell of clear cool weather. Large ripe cornices are also of concern and will be a problem with additional loading, especially when the sun and warm temperatures come back. The March 25th crust with facets appears to be inactive, but is worthkeeping on the radar with forecast snow and wind.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.