Avalanche Forecast
Issued: Apr 21st, 2019 3:58PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Wind Slabs.
dsaly,
Avalanche Canada
Travel early, a warming snowpack will increase the chance for loose wet avalanches through the day. Wind slabs may lurk in the alpine.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
SUNDAY NIGHT: Mostly clear, moderate southwest wind, alpine temperature -1 C, freezing level 1900 m.
MONDAY: Cloudy with flurries up to 8 cm, moderate southwest wind with gusts to 60 km/h, alpine temperature +2 C, freezing level 2400 m.
TUESDAY: Cloudy with flurries up to 5 cm, moderate west wind, alpine temperature 0 C, freezing level 2300 m.
WEDNESDAY: Mix of sun and clouds, light to moderate west wind wind, alpine temperature -1 C, freezing level 2400 m.
Avalanche Summary
On Saturday morning evidence of large natural wind slab avalanche cycle was observed on all aspects above 1500 m; natural avalanches continued throughout the day, two large (2.5-3) natural wind slab avalanches were observed around 3 pm on south aspects. Storm and wind slab avalanches to size 3 were triggered with explosives on all aspects in the alpine (above 2300 m). Impressive results were recorded including sympathetic avalanches to size 2.5; one shot triggered 6 large avalanches as far as 600 m away.
On Friday, a natural wet slab avalanche cycle to size 3 was reported on all aspects from 2200-2700 in the western part of the forecast region. Toward the east, natural wet loose avalanches size 1.5-2.5 were seen on north-northeast aspects at 1900 m.
Snowpack Summary
Sun and temperatures pushed freezing levels upwards of 2400 m on Sunday with limited freeze/crust recovery expected overnight. In high alpine terrain sheltered from the sun, up to 20 cm loose snow may prevail, likely being impacted by southwesterly winds. Below 2400 m a temperature crust has developed, the strength of which will depend on overnight recovery and the speed at which the snowpack warms during the day.
Weak and sugary faceted grains may remain at the bottom of the snowpack in the alpine, producing a low likelihood but high consequence scenario. Steep, rocky areas with a shallow snowpack are the most likely places to trigger this layer. Below 1200 m the brown pow is showing, bike season is fast approaching.
Problems
Loose Wet
The likelihood of loose wet avalanche activity will increase during periods of intense sun, particularly where it moistens previously dry snow at higher elevations.
- Minimize overhead exposure and avoid steep slopes during periods of strong sun.
- Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.
- Use extra caution on slopes if the snow is moist or wet.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Over the weekend, large (up to size 3) storm/wind slab avalanches were observed in the alpine. In areas that accumulated larger snowfall amounts over the weekend, these slabs may still be reactive to human triggers.
- Use small, representative slopes without consequence to test the bond of the recent snow.
- Expect conditions to change rapidly with aspect and elevation.
- Be careful with wind-loaded pockets, especially near ridge crests.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 22nd, 2019 2:00PM
