Avalanche Forecast

Issued: Feb 16th, 2018 4:28PM

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

jmcbride, Avalanche Canada

Northwest Inland.

Wind and recent storm snow have created slabs at upper elevations. Reactivity of these may increase if the sun starts to pack a punch on solar aspects.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY: Mix of sun and cloud. Ridge wind moderate to strong, northeast. Temperature -16. Freezing level valley bottom.SUNDAY: Mostly sunny. Ridge wind, moderate, northeast. Temperature -15. Freezing level valley bottom.MONDAY: Mostly sunny. Ridge wind moderate, northwest. Temperature -10. Freezing level valley bottom.

Avalanche Summary

There have been no new reports of avalanches since Wednesday when widespread natural avalanche activity up to size 2 was reported on wind-loaded, leeward slopes as well as loose snow releases on steep solar aspects in the afternoon.Last weekend when we received reports of continued natural wind slab activity near Smithers. See this MIN report from Sunday.Also from last weekend, several natural avalanches up to size 3 were reported (particularly on northeast facing slopes at higher elevations) as the winds picked up and slab avalanches ran surprisingly far. See this MIN post for more information. See here for a stunning photo of a large avalanche. This included a skier triggered size 2 persistent slab avalanche on a south facing sparsely treed (deciduous) slope just north of Hankin. See here for the MIN report.

Snowpack Summary

Winds (mostly northwesterly) have scoured wind-exposed slopes and created wind slabs up to 50 cm thick on leeward slopes at tree line and above. In areas sheltered from the wind, you'll find 30-50 cm of settled storm snow. A crust and/or weak feathery surface hoar layer buried in mid-January now lies about 100 cm below the surface. The crust exists well into the alpine and the surface hoar can be found in sheltered areas in the lower alpine and tree line elevations. Snowpack tests produced hard, sudden results on weak, sugary snow crystals associated with this crust in the Smithers area, indicating that this is still a layer of concern to watch for.Another two crust / surface hoar layers that were buried in December are now 100-150 cm below the surface. These layers have produced sudden results in recent snowpack tests and may still be sensitive to triggering from shallow snowpack areas.See here for a good summary of recent snowpack test results near Smithers.

Problems

Wind Slabs

Winds have formed wind slabs in exposed areas at tree line and above. Expect these slabs to be reactive to human triggering and keep in mind that a release may also step-down to a deeper layer buried in the snowpack.

Avoid lee and cross-loaded terrain near ridge crests or convex rolls.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Persistent Slabs

Weak layers buried 100-150 cm below the surface have been reactive in snowpack tests and have also produced a few large avalanches recently. These layers may also remain sensitive to human triggering in shallow snowpack areas.

Avoid shallow or thick to thin snowpack areas where triggering a deeper layer is more likely.Avoid lingering in runout zones, avalanches triggered from above may run long distances.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Feb 17th, 2018 2:00PM