Avalanche Forecast
Issued: Apr 17th, 2019 4:40PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
cgarritty,
Avalanche Canada
The storm is set to finish with a bout of intense southwest winds, which are expected to move much of our new snow into reactive slabs. Expect the greatest new snow amounts - and avalanche danger - at high elevations in the southwest of the region.
Summary
Confidence
Moderate -
Weather Forecast
Wednesday night: Cloudy with continuing scattered flurries with a trace to 5 cm of new snow. Strong to extreme southwest winds.
Thursday: A mix of sun and cloud. Moderate to strong southwest winds easing over the day. Alpine high temperatures around -6 with freezing levels to 1400 metres.
Friday: Cloudy with sunny periods and isolated flurries with a trace of new snow. Light to moderate west winds. Alpine high temperatures around -7 with freezing levels to 1200 metres.
Saturday: Mainly sunny. Light south winds. Alpine high temperatures around -4 with freezing levels to 1600 metres.
Avalanche Summary
No new avalanches have been reported in the region, however up to 27mm of new precipitation has been observed in the southwest of the region. Avalanche danger will be greatest where new snow accumulations are deepest.
Reports from Monday included an observation of our recent snow reacting easily to skier traffic on south aspects, producing loose wet avalanches to size 1.5, particularly in areas with a thinner cover of new snow.
On Sunday natural wind slabs to size 1.5 were observed on northeast facing slopes between 1400 and 1800 m. A natural cornice failure produced a size 2.5 wind slab when it impacted the underlying slope.
On Saturday loose wet sluffing from gulley walls was reported below treeline. Avalanches were also heard, but not seen running from big unskiable terrain.
If you're out we'd love it if you would submit what you're seeing to the Mountain Information Network.
Snowpack Summary
Another 2-5 cm on new snow is expected to accumulate Wednesday night, bringing variable new snow totals to an expected 10-30 cm, which is focused to the west of the region. The new snow has buried a melt freeze crust recently formed at treeline and below as well as on slopes that saw sun exposure after Saturday's storm. It will add to a wind-redistributed 10-30 cm of dry snow (from the weekend) on high elevation north facing slopes.
As we enter into mid-April we're dealing with a classic warm snowpack. At and below treeline the snowpack is becoming isothermal. We're tracking the April 4th crust which is down 15 to 30 cm below the surface on high elevation north facing slopes. Surface hoar and facets have been observed on this crust and it has recently produced sudden planar results in snowpack tests.
Problems
Wind Slabs
Strong winds are expected to strip our new snow from windward (south to west) slopes and build fresh slabs on lee (north to east) slopes. This problem is likely to increase with elevation and toward the southwest of the region.
- A bed surface of crust may prevent new snow from bonding well on south through west aspects.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Look for signs of instability like whumphing, shooting cracks, and recent avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 18th, 2019 2:00PM
