Avalanche Forecast
Issued: Apr 19th, 2019 4:48PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
cgarritty,
Avalanche Canada
New snow is expected to accumulate as rain transitions to snowfall over Friday night. As flurries persist, danger from new wind slabs will increase. Be sure to post your observations to the Mountain Information Network!
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Friday night: Cloudy with scattered showers transitioning to alpine flurries as freezing levels descend from 2700 to 1800 metres. Light to moderate southwest winds easing and shifting to northeast.
Saturday: A mix of sun and cloud with isolated alpine flurries. New snow totals of 5-10 cm. Light rain below about 1700 metres. Light east winds. Alpine high temperatures around -1 with freezing levels to 1900 metres.
Sunday: Mainly sunny. Light southeast winds shifting to southwest. Alpine high temperatures around +3 with freezing levels to 2500 metres, remaining elevated overnight.
Monday: A mix of sun and cloud with cloud increasing over the day. Light to moderate southwest winds increasing over the day. Alpine high temperatures around +5 with freezing levels to 2700 metres.
Avalanche Summary
No new avalanches have been reported in the region. Please submit your observations to the Mountain Information Network.
An observation from the Waterton Park area describes a very large (size 3) deep persistent slab having released with a cornice trigger at some time in the past week. This occurred on a wind loaded high (2500m) north aspect on Mt. Blackiston and initiated as a wind slab before 'stepping down' to weak faceted snow in the basal snowpack. This should be treated as a reminder of the potential for weak basal snowpack conditions persisting in high alpine terrain.
Snowpack Summary
Friday's rain is expected to create moist snow conditions on all aspects and elevations. By Saturday morning, cooling temperatures may allow for a trace to 5 cm of new snow to accumulate in the alpine before precipitation ends. The above mentioned rain is saturating approximately 10 to 20 cm of dense snow from the past weekend's storm. In most areas, this storm snow sits above a widespread supportive crust.
North facing alpine terrain may see more pronounced loose wet activity as rain saturates previous storm snow that until recently remained cold and dry. High elevation north facing terrain also harbours a deeply buried layer of facets. Although unlikely, human triggering of persistent slabs on this layer may still be possible in rocky alpine terrain with shallow or variable snowpack depth.
Below treeline the snowpack has melted or is isothermal.
Problems
Wind Slabs
Thin new wind slabs may form over Friday night and Saturday as rain transitions to snowfall at higher elevations. Any slabs that form should be ripe for human triggering.
- Use caution in lee areas where wind loading may create fresh wind slabs.
- Shifting wind direction could make it tricky to pinpoint the aspects where new slabs have formed.
- Be alert to conditions that change with elevation.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 20th, 2019 2:00PM
