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Avalanche Forecast

Archived

Mar 10th, 2024–Mar 11th, 2024

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Coquihalla, Manning, Skagit.

Flurries and gusty wind will maintain an elevated avalanche hazard. Choose simple terrain and avoid being under steep slopes and large avalanche paths.

Confidence

Moderate

Avalanche Summary

On Friday, a large (size 2) glide slab avalanche was observed near the Coquhalla summit. Note that we have had limited field reports in this region.

Snowpack Summary

Up to 30 cm of recent snow is settling quickly. A surface crust may have formed on south and west aspects and lower elevations, wind-affected surfaces are found in open and exposed areas.

Below recent snow, 60-100 cm settling snow covers a crust/facets or surface hor and is the failure plane responsible in many recent avalanches. Reports indicate that some areas have a second crust at a similar depth. In either case, these crusts continue to produce whumpfs and concerning snowpack test results at treeline.

Weather Summary

Sunday night

Scattered flurries, up to 10 cm snow. Southwest ridgetop wind 30-50 km/hr. Treeline temperature -4 °C. Freezing level dropping below 900 m.

Monday

Cloudy with isolated flurries, and up to 5 cm snow. South ridgetop wind 40 gusting to 70 km/hr. Treeline temperature -4 °C. Freezing level around 1200 m.

Tuesday

Cloudy with flurries, 5-15 cm wet snow. Southwest ridgetop wind gusting to 50 km/hr. Treeline temperature -3 °C. Freezing level around 1200 m.

Wednesday

Mostly cloudy. Southwest ridgetop wind 30-50 km/hr. Treeline temperature -6 °C. Freezing level dropping below 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Choose low-angled, sheltered terrain where new snow hasn't been wind-affected.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Closely monitor how the new snow is bonding to the crust.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.