Avalanche Forecast

Issued: Mar 27th, 2017 4:29PM

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

Avalanche Canada mgrist, Avalanche Canada

Wind slabs will be building at higher elevations: Dial back your terrain use on Tuesday and assess conditions carefully.

Summary

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

We're looking at a series of small systems impacting the region throughout the forecast period. The winter weather train keeps rolling into town! TUESDAY: 5-15 cm Monday overnight into Tuesday afternoon, strong southwest wind, freezing levels 1300m. WEDNESDAY: Lingering flurries (5cm possible) moderate south wind, freezing levels 1200m, alpine temperatures around -4 C. THURSDAY: Snow in the afternoon (5cm). Moderate south wind, freezing level around 1200 m with alpine temperatures around -3 C.

Avalanche Summary

On Sunday a Size 2 natural wind slab (average depth 40cm) was reported on a northeast aspect near 1800m in the south of the region. On Saturday, several wind slabs to Size 1.5 were reported on (east) northeast aspects in the north of the region.On Friday, loose snow avalanches were reported at treeline in steep terrain in the south of the region.The incoming weather will add load to the persistent slab, and human triggering remains possible in steep or unsupported terrain. 

Snowpack Summary

Variable and unsettled weather has given 5-15cm of new snow in the past few days. Winds have been moderate to STRONG southerly, but most exposed surfaces are either heavily scoured or wind-pressed firm by now.Recent warming and sun have likely left a crust on solar aspects and below 1300 m (reportedly breakable crust below 1000m). Snow from the past week or so has settled into a 20-60 cm thick slab above an older crust interface. Reports suggest the bond to the crust is poor and has resulted in a reactive slab, in addition to weaknesses down 30-35cm within the storm snow itself (giving sudden planar results in snowpack tests).Weak sugary snow near the ground has been a dormant instability, but it may still be possible to trigger in steep rocky terrain.

Problems

Wind Slabs

An icon showing Wind Slabs
Moderate to strong south winds and some incoming snow will create more wind slabs on north through east aspects at upper elevations.
Use caution in lee areas. Recent wind loading have created wind slabs.Be careful with wind loaded pockets. Be aware of wide variation in snowpack depthBe aware of thin areas that may propogate to deeper instabilites.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
A 20-60 cm thick slab above a rain crust has been reactive to human triggers over the past week. Most activity has been in wind-affected terrain. Persistent slabs also have the potential to step down to deep basal weaknesses near the ground.
If triggered the persistent slabs may step down to deeper layers resulting in large avalanches.Avoid steep convexities or areas with a thin or variable snowpack.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Mar 28th, 2017 2:00PM