Avalanche Forecast
Issued: Apr 12th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
mconlan,
Avalanche Canada
Strong wind and new snow are likely keeping wind slabs reactive. Seek sheltered terrain for the best riding conditions.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
MONDAY NIGHT: Cloudy with snowfall, accumulation 2 to 5 cm, 50 km/h southwest wind, alpine temperature -5 C.
TUESDAY: Cloudy with snowfall, accumulation 2 to 5 cm, 50 km/h southwest wind, alpine temperature -4 C, freezing level rising to 1000 m.
WEDNESDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 60 km/h south wind, alpine temperature -2 C, freezing level 1200 m.
THURSDAY: Partly cloudy, 20 km/h southeast wind, alpine temperature 0 C, freezing level 1500 m.
Avalanche Summary
On Friday, the field team observed natural wind slabs from a steep, alpine south facing gulley features around White Pass. They were also able to remotely triggered multiple size 1 to 2 wind slabs, with the furthest avalanche releasing 350m away! The reactive wind slabs ran on a 2 cm thick melt-freeze crust down 30 to 70 cm. On Saturday, the field team continued to investigate these slabs, found them to be reactive (see here), and suspected they would be so for a few more days.
Snowpack Summary
Around 15 cm of snow from Friday was redistributed by strong northeast wind in exposed terrain, forming touchy wind slabs everywhere except in sheltered terrain. The wind effect is particularly widespread along the highway corridor at White Pass but may be less so as you push into the side valleys from the highway. The slabs overly a hard melt-freeze crust on sun-exposed slopes up to 1300 m. New snow on Monday through Wednesday will be accompanied by strong southwest wind, likely keeping wind slabs reactive above the rain-snow line.
The White Pass area has a deep snowpack without any deeper layers of concern. The Tutshi Lake / Paddy Peak area should be assessed on a slope by slope basis, as some lingering snowpack weaknesses may still exist on isolated slopes. The Wheaton's shallower snowpack is dominated by hard wind slabs overlying sugary facets and depth hoar. It's an untrustworthy snowpack structure that requires conservative terrain selection and diligent travel habits.Â
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
New snow and strong wind will likely continue to make wind slabs reactive to riders in exposed terrain. Use caution in steep, wind-affected terrain and look for signs of instability prior to committing yourself. Wind slabs may be particularly touchy on sun-exposed slopes up to 1300 m, where they overly a hard melt-freeze crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 14th, 2021 4:00PM
