Avalanche Forecast

Issued: Mar 19th, 2023 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.

Avalanche Canada dsaly, Avalanche Canada

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Warm spring daytime temperatures are here - watch for surface snow turning wet and be wary of cornices and overhead hazards.

Summary

Confidence

Moderate

Avalanche Summary

Wet-loose avalanches to size 1.5, occurring on east to south aspects, likely solar-induced, were reported on Friday and Saturday.

On Wednesday, dry loose natural avalanches were seen from steep terrain up to size 1.5. A skier-controlled size 1 wind slab and several natural cornice failures up to size 2 were also reported. There are limited observations from the far northern end of the forecast region, however, a reactive layer of surface hoar buried under the recent storm snow was reported near the Homathko Icefield. On Wednesday, skiers found a reactive layer of surface hoar buried 65 cm deep below the recent storm snow, and observed natural avalanches to size 3.

On Tuesday, several skier-controlled slab avalanches (size 1.5) were reported on wind-loaded features at treeline and above. Dry loose sluffing was noted from steep northeast terrain up to size 1.5.

On Monday, several natural cornice falls were reported in the northern part of the region up to size 2.5.

On Sunday, a natural large size three, wind slab avalanche was observed. It started in a cross-loaded feature in the alpine and it may have stepped down to weaker buried layers.

Snowpack Summary

Daytime warming or wet flurries will promote moist snow surfaces, continuing to destabilize the upper snowpack. Cornices loom over ridgelines and may become weak during periods of solar radiation or warming.

A sun crust has formed on all aspects up to 1800 m and solar aspects into the alpine. On more northerly and sheltered slopes at upper treeline and higher, 20-40 cm recent snow covers an older sun crust on steep solar aspects, and older faceted snow in sheltered areas. Recent southwest wind pressed surfaces and formed slabs on lee slopes at exposed treeline and into the alpine.

The mid-snowpack is well consolidated. There is a widespread weak layer of large sugary facets at the bottom of the snowpack. Recent avalanche activity on this layer has been confined to northern parts of the region in the Chilcotins. This layer remains a concern in shallow snowpack areas.

Weather Summary

Sunday night

Starry sky with increasing clouds. Southeast wind 5-15 km/hr. Treeline low temperature -6 C. Freezing level dropping below 1100 m.

Monday

Light flurries through the day, trace to 5 mm. Southeast wind 10-20 km/hr. Treeline high temperature +1 C. Freezing level 1500 m.

Tuesday

Sunny and clearing skies. Light northeast wind. Treeline high temperature +2 C. Freezing level 1600 m.

Wednesday

Sunny and calm. Light southerly wind. Treeline high temperature +2 C. Freezing level 1600 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Wind Slabs

An icon showing Wind Slabs

On sheltered, polar aspects at higher elevations dry snow prevails. With forecast increased wind and light flurries, watch for reactive slabs where snow is redistributed.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Loose Wet

An icon showing Loose Wet

Strong solar radiation or warm temperatures may still produce moist surface snow and a wet-loose avalanche hazard. A weak pulse of wet flurries through Monday may prolong this hazard. As temperatures drop and a crust forms this problem will disappear. Cornices are large and recently fragile - give them space.

Aspects: South East, South, South West, West.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 1.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

A layer of weak facets sits near the base of the snowpack. This layer is most likely to be problematic in steep, wind-loaded terrain where the snowpack depth varies from thick to thin. Especially in the northern part of the region around the Chilcotins, Birkenhead, and Hurley.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3.5

Valid until: Mar 20th, 2023 4:00PM

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