Avalanche Forecast

Issued: Apr 23rd, 2018 4:01PM

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

jsmith, Avalanche Canada

Northwest Coastal.

Sunshine and rising temperatures will elevate the avalanche danger throughout the week. Be aware of changing conditions throughout the day and avoid overhead hazards.This is our final daily forecast for the season which will expire on April 25th.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

TUESDAY: Mix of sun and cloud. Light to moderate west wind. Alpine temperature +4. Freezing level 1500 m. WEDNESDAY: Sunny. Light west wind. Alpine temperature +9. Freezing level rapidly rising to 3200 m. THURSDAY: Sunny. Light southwest wind. Alpine temperature +12. Freezing level 3000 m.

Avalanche Summary

Several very large deep persistent slab avalanches(size 3-4) which were triggered by cornice failures and several natural wind slabs up to size 2.5 were reported near Bear Pass on Saturday. Avalanche reports have been limited due to very few information sources this time of year. If you have been out, please post your observations on the Mountain Information Network. (MIN)

Snowpack Summary

Cornices are large and when they fail there is the potential to trigger large avalanches on deeply buried weak layers. Lingering wind slabs may be reactive to human triggers on leeward slopes below ridgetops.In the south of the region, two layers of surface hoar are buried approximately 70-100 cm deep and most prominent on north to east aspects. Further north, these layers are around 40 cm deep. Below these March layers the mid-pack is generally well-settled and strong. In the far north of the region there are weak sugary facets near the bottom of the snowpack.

Problems

Loose Wet

Sunshine and warming temperatures will increase the loose wet avalanche activity throughout the week.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Watch for signs that the snow is heating up such as pin-wheeling or the surface snow becoming moist.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 - Very Likely

Expected Size

1 - 2

Cornices

Sunshine and warming temperatures will increase the likelihood of cornice failures.

Falling cornices may trigger persistent weak layers deeper in the snowpack.Cornices become weak with daytime heating. Give them a wide berth both from above and below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3.5

Valid until: Apr 24th, 2018 2:00PM