Avalanche Forecast

Issued: Apr 19th, 2014 9:30AM

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.

jlammers, Avalanche Canada

Kootenay Boundary.

Check out this Forecasters Blog post for more info on how to manage risk during the spring. Here's a quote: "resist the urge to rely on danger ratings alone". Conditions change rapidly at this time of year and you need to stay tuned in locally.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Sunday: Mix of sun and cloud / Light to moderate southwest winds / Freezing level at 1700 mMonday: Overcast skies / Moderate south winds / Freezing level at 2600 mTuesday: Moderate snowfall / Moderate southwest winds / Freezing level dropping throughout the day to about 1900 m

Avalanche Summary

Recent observations have been limited, although on Friday we received reports of several size 1 wind slabs within the recent storm snow with at least 1 stepping down to a recently buried melt-freeze crust.Last Sunday there was a report of a size 2.5 natural deep persistent slab in the Rossland Range in response to strong solar radiation and warm temperatures. This avalanche released on a steep southeast aspect at around 2100 m and likely failed on the mid February weak layer. It's a good reminder of the potential for large deep avalanches under certain conditions.

Snowpack Summary

Some areas may have received between 40 and 50 cm of snow in the last 3 days, with a snow line somewhere around 1500-1600 m. Below the recent snow you'll likely find a melt-freeze crust in many areas. Moderate to strong westerly winds have shifted the recent accumulations into wind slabs in higher elevation lee terrain. Reports from the field indicate a weak bond exists within the storm snow, although I expect moderate temperatures over the weekend will help to settle and strengthen the new snow. The late January/early February persistent weak layer is deeply buried but could still wake up during periods of heavy precipitation (especially rain) or significant warming and solar radiation. Cornices are large in some areas and should be given a wide berth.

Problems

Wind Slabs

Recent storm accumulations have been shifted by moderate to strong winds into wind slabs in the lee of ridge crests and terrain breaks. Human triggering may still occur in steep, unsupported terrain.

Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Warm temperatures and sun will promote pushy loose wet avalanche activity. Watch for increased reactivity in the afternoon on steep, sun-exposed terrain.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

This problem is unlikely but should remain on the radar. We could see this wake up again this weekend with forecast warming and strong solar radiation.

Use caution on big alpine slopes, especially around thin areas that may propagate to deeper instabilities.>Be aware of the potential for large, deep avalanches due to the presence of buried persistent weak layers.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Apr 20th, 2014 2:00PM