Avalanche Forecast

Issued: Mar 25th, 2016 9:12AM

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

bcorrigan, Avalanche Canada

Northwest Coastal.

New snow with light SW winds will continue to build wind slabs on the lee sides of ridges at treeline and above. Cornices continue to grow, pay special attention to cornices and their run outs.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

The Northwest Coast should see a steady progression of relatively weak frontal systems through the weekend. TODAY: Freezing level around 1200 m, 1 to 5 cm of snow, light to moderate south winds. SATURDAY: Freezing level around 1300 m, possible 2 to 15 cm of snow, winds forecast to be moderate from the southeast. SUNDAY: Freezing level dropping to 600 m overnight, then climbing to 1200 m during the day, possibility of light convective flurries, light winds forecast from the south west. MONDAY: Cloudy with clearing skies, freezing level dropping to 600 m overnight, then beginning a rise to 2000 m by Tuesday. For more detailed mountain weather information visit avalanche.ca/weather

Avalanche Summary

Reports from yesterday tell of moist snow, loose-wet avalanches up to size 1.5 on solar aspects, and in the north of the region, a natural size 2 avalanche was observed on north facing terrain at 2100 m. It is believed to have been the new storm snow running on March 23rd surface hoar. The slab was 25 cm deep and started on a 40 slope.

Snowpack Summary

In the last 48 hours 5 to 10 cm of snow has fallen accompanied by moderate to strong southerly winds. At treeline and in the alpine small wind slabs are expected to have formed. These wind slabs overlie a variety of surfaces which include a hard crust on solar aspects above 1300 m, moist or refrozen snow on all aspects below 1300 m, and settled wind slabs in exposed high elevation terrain. A layer of surface hoar or melt-freeze crust buried on March 3 is down 50-80 cm and has been on the radar of professionals in the mountains north of Stewart. A more widespread crust/facet layer buried in early February can now be found down over a metre. Both of these deeper layers have become less likely to trigger, but have the potential for large avalanches especially with a large trigger such as a cornice fall. I'd be increasingly cautious during periods of warming and intense solar radiation.

Problems

Wind Slabs

Recent storm snow accompanied by moderate to strong SW winds have formed wind slabs on lee slopes at treeline and above.

Be cautious as you transition into wind affected terrain. >Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Avoid cross loaded slopes at or above treeline.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornices are becoming big and heavy, take great care around these beasts !

Extra caution needed around cornices with current conditions.>Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

This slab may be hard to trigger, but a large shock like a cornice could produce a very large, destructive avalanche

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar. >Conditions have improved, but be mindful that persistent instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 26th, 2016 2:00PM