Avalanche Forecast

Issued: Jan 3rd, 2015 3:00PM

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

Peter, Avalanche Canada

Northwest Coastal.

Winds will be the issue in the short term. Seek sheltered terrain and be aware of what is above you.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A strong Pacific frontal system will impact the Coast beginning on Sunday morning. Expect locally heavy snowfall (15-25 cm) and strong outflow winds as the moist Pacific airmass battles with the Arctic front. Ridge winds should also increase to very strong from the S-SE. Monday could be a bit drier before another frontal system arrives late in the day or overnight. This pulse should drop another 20-30 cm through Tuesday with moderate SW ridge winds. The freezing level remains at valley bottom and outflow winds should be a factor each day.

Avalanche Summary

Avalanche activity was limited to isolated thin human-triggered wind slabs and loose dry sluffs on Friday. Expect fresh wind and storm slabs to develop over the next few days. These slabs could release naturally, especially in leeward terrain, or from human triggering.

Snowpack Summary

On Saturday temperatures plummeted and outflow winds cranked up again - likely created new wind slabs in exposed southwest to northwest facing terrain. Recent snowfall amounts seem to vary from 10 cm up to around 30 cm. This new snow sits on a variety of old surfaces including surface hoar, a crust, or older wind slabs. The surface hoar, down 25-35 cm, may be more prevalent in northern sections like Bear Pass and Ninginsaw Pass. The mid December crust can be found down around 40 to 80 cm and is sandwiched with facets and surface hoar. The mid November crust down 70 to 175 is gaining strength but is still reactive in test profiles. The deeper snowpack weaknesses could 'wake up' with heavy loading from new snow and wind.

Problems

Wind Slabs

Strong NE-SE outflow winds may create dense or hard wind slabs in exposed lee terrain at all elevations. Combine the the strong winds with cold new snow and we could see deep deposits in some areas.

Avoid travelling in areas where outflow winds may be reverse or cross-loading slopes.>Choose well supported terrain without convexities.>Minimize exposure to avalanche terrain during periods of heavy loading from new snow, wind.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Loading by new snow and wind could be enough to trigger deeper persistent weaknesses in the snowpack.

Use caution around convexities, ridge crests, rock outcroppings and anywhere else with a thin or variable snowpack.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 6

Valid until: Jan 4th, 2015 2:00PM