Forecast snowfall amounts for Thursday may vary greatly due to the convective nature of the weather system passing through.
Confidence
Low - Due to the number of field observations
Weather Forecast
THURSDAY: Cloudy with isolated flurries / Light-Moderate southwest wind / Alpine temperature -3 / Freezing level 1900mFRIDAY: Mix of sun and cloud / Light to moderate west wind / Alpine temperature -2 / Freezing level 2100mSATURDAY: Cloudy with sunny periods / Light south wind / Alpine temperature 0 / Freezing level 2400mNOTE: Convective flurries, which are common this time of year, can result in widely varying snowfall amounts. These spring squalls routinely drop 20+ cm of snow in one valley while the adjacent drainage remains dry. For this reason, the distribution of avalanche problems associated with new snow vary greatly within a region.
Avalanche Summary
Recent reports are very limited but include human triggered avalanches to size 1.5 on west and east aspects at tree line. These were isolated to recent storm snow accumulations 25cm deep. Exposure to large overhanging cornices remains a significant concern.
Snowpack Summary
Recent new snow tree line and above has been redistributed by west and south winds. Cornices remain large and continue to become more overhanging. The middle of the snowpack is generally well settled and continues to transition into a spring melt/freeze regime except for high elevation northerly aspects. Expect the entire thickness of the snowpack to be moist or wet at lower elevations. At upper elevations a deep persistent layer consisting of facets sitting on a crust that was buried back in November has been sporadically reactive to heavy loads i.e. a cornice fall or the weight of a smaller avalanche running.
Problems
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.
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.