Avalanche Forecast

Issued: Apr 9th, 2012 10:21AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Loose Wet, Cornices and Persistent Slabs.

swerner, Avalanche Canada

South Rockies.

Freezing levels are expected to rise to 3000 m for the next two days. Treeline temperatures steady near +6 accompanied by intense solar radiation and limited re-freeze. Expect danger ratings to remain elevated through the forecast period.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Thursday

Weather Forecast

The beautiful weather we've been seeing over the past few days will start to change as a dominating upper ridge begins to break down, and turn to a warm Southerly flow. A series of systems caught in this flow will affect the region through to Friday. Tuesday: Continued sunny, cloudless skies with light ridgetop winds from the SW. Freezing levels could reach 3000 m. A temperature inversion may redevelop bringing warmer alpine temperatures through the night. Treeline temperatures steady near +5 C. Wednesday: A mix of sun and cloud with possible afternoon rain showers. Treeline temperatures near +10, with freezing levels 3000 m. Thursday: Possible 20 mm of precipitation (mix rain and snow) through the day, with freezing levels falling to 1500 m. Ridgetop winds moderate from the West.

Avalanche Summary

No recent avalanche activity has been reported. On Friday in the Fernie area a skier triggered a size 1.5 avalanche with a 20 cm crown on an E facing slope at 2000 m Friday. Some loose snow activity on a SE facing slope was also reported, but, there is surprisingly little avalanche activity in the region currently.

Snowpack Summary

Spring like weather, and conditions have promoted settlement and bonding of last week's storm snow over the April 4th melt/freeze crust, producing little avalanche activity. Below this a cohesive slab 60-120 cm (depending on the drainage) sits on the March 27th interface. Our field team was out in the region Saturday; they were able to find the March 27th interface down around 90cm but test profiles did not produce any results on this layer. Large cornices loom over many lee slopes. Glide cracks are a concern, be sure to give them a wide berth as they are very sensitive and could fail at any moment.

Problems

Loose Wet

Strong sun and rising freezing levels are forecast for Tuesday/Wed. Watch for loose wet avalanches; especially on Southerly slopes. There may be potential for deeper slab avalanches on slopes that bake all day under the strong spring sun.

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

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

1 - 5

Cornices

Large cornices have formed. Cornices receiving direct sun will eventually grow weak, with potential for cornice fall to initiate deep persistent slab avalanches on underlying slopes. Pay attention to what's happening above you.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

3 - 7

Persistent Slabs

The odd deep slab could still be out there, I'm still suspect of steeper unsupported slopes & places where the snowpack goes from thick to thin, especially near ridge crest and around rock outcroppings.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Apr 10th, 2012 9:00AM