Archived

Avalanche Forecast

Feb 26th, 2014–Feb 27th, 2014

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

Check out the new Forecaster Blog for an update on the “Touchy Weak Layer.”

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Thursday

Weather Forecast

Overnight and Thursday: Warm air continues to be trapped in the alpine overnight and during the day Thursday. Freezing levels dropping Thursday afternoon with light Northerly winds and high cloud. No precipitation.Friday: Freezing levels at valley bottoms and alpine temperatures trending colder under sunny skies. Gusty strong outflow winds at lower elevations and light Northerly winds in the alpine.Saturday: Cold clear and sunny. Strong Northeast winds with very strong outflow winds in the major valleys.

Avalanche Summary

Natural avalanches up to size 3.0 were reported from several areas of the region due to reverse loading from the outflow winds above the early February persistent weak layer. Forecast strong solar radiation and high freezing levels may cause moist or wet avalanches on Southerly aspects.

Snowpack Summary

Warm alpine temperatures and strong solar radiation have resulted in snowballing and moist or wet loose snow on steep Southerly aspects. Strong N-SE outflow winds have resulted in reverse loading and cross loading in exposed terrain at all elevations, and have scoured exposed windward slopes. The prominent mid February persistent weakness (surface hoar, facets, crust and/or wind pressed surfaces) is down 60-100 cm in the north and 120-160 cm in the south. Snowpack tests are now giving moderate to hard "pops or drops" shears on this weakness, and several whumpfs are still being reported. Basal facets and/or depth hoar remain a concern in shallow snowpack areas in the northern part of the region. Cornices are also large and may become weak if northerly winds start to undercut them.

Avalanche Problems

Persistent Slabs

The early February persistent weak layer continues to be sensitive to any additional load. Forecast solar radiation may trigger another round of natural activity on the buried weak layer.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 5

Wind Slabs

Northerly or Easterly outflow winds may reverse load slopes that have been previously stripped of storm snow. These new wind slabs may be triggered by forecast solar radiation.

Avoid freshly wind loaded features.>Avoid travelling in areas that have been reverse loaded by winds.>

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

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Loose Wet

Forecast solar radiation may release moist or wet snow from steep Southerly aspects. Wet snow in motion may step down to deeply buried weak layers.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

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

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3