Avalanche Forecast

Issued: Mar 16th, 2014 11:05AM

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

ghelgeson, Avalanche Canada

South Columbia.

Summary

Confidence

Fair

Weather Forecast

Synopsis: Snowfall should taper late Sunday as the flow dries, cools & shifts to the NW. Some weak ridging builds in for Monday and Tuesday. The models show a timid system set to arrive late Tuesday night.Sunday Night: Freezing Level: 1400m lowering to 700m; Precipitation: 3:7mm - 5:15cm (locally heavy convective snowfall possible); Treeline Wind: Light, SW | Moderate NW at ridgetopMonday: Freezing Level: 900m - 1300m; Precipitation: 1:3mm - 1:5cm; Treeline Wind: Light, NW | Moderate NW at ridgetopTuesday: Freezing Level: 500m rising to 1500m; Precipitation: Nil; Wind: Light, SWWednesday: Freezing Level: 1100m - 1600m; Precipitation: 2:4mm - 2:10cm; Treeline Wind: Light, SW | Moderate SW at ridgetop

Avalanche Summary

Avalanche activity on Saturday was limited to loose dry sluffs and small very soft slabs running on the Mar 13th crust. On Friday there was also a report of a size two avalanche that was triggered accidently on a North facing slope at treeline on the early March surface hoar/crust combo. On Thursday explosive control produced avalanches to size 3 on both SE & NE facing slopes in upper treeline and alpine elevations. A skier remote triggered a size 3 avalanche from 100m away on a NE facing slope at 2200m. The avalanche was triggered from low angle terrain and resulted in a very large avalanche with a crown up to 150cm in depth. Last Saturday's avalanche fatality occurred in the Keefer Lake area northeast of Cherryville. The avalanche, which occurred in a cut block at about 1700m, involved 3 sledders who were in a party of 6. Two of the men were able to inflate their airbags and were partially buried. The deceased was reportedly not able to inflate his airbag, and was buried approximately 5m below the surface.While not in this region, it's worth taking a look at last weekends incident from the Cariboos.

Snowpack Summary

The storm came in warm and produced 10 - 35 cm of snow that is now resting on the old surface which consists of mix of 3 - 6mm surface hoar and crust. Last weeks storm snow has settled into a 50 - 100 cm slab that rests on the early March interface consisting of small grained surface hoar in sheltered areas and a sun crust on solar aspects.Ridgetop cornices remain large and unsupported.The February 10th surface hoar/facet/crust combo is 80cm - 250cm below the snow surface and widespread throughout the region. Surface avalanches in motion and cornice fall still have the potential to initiate an avalanche on this deeply buried weak layer. Remote triggering on this layer is ongoing. The mid and lower snowpack are strong and well consolidated.

Problems

Storm Slabs

The storm came in warm which should allow the 10 - 35 cm of new snow to settle and bond to the Mid March crust/surface hoar interface over the next few days. Watch for wind slab development immediately lee of ridge crest.

Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious of sluffing.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The early March suncrust/surface hoar combo should not be underestimated. While there's a lot of uncertainty and complexity surrounding this layer, it's important to note that human triggering is most likely at treeline.

Watch for terrain traps where avalanche debris can accumulate into deep deposits.>Given all the uncertainty surrounding this slab, I advise against stepping out into terrain with any kind of consequence.>The trees are not the safe-haven they normally are at this time. Terrain at treeline is primed for human triggered avalanches. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 5

Deep Persistent Slabs

The early February Persistent Weak Layer is still active and has produced some stunning avalanches recently. Very large avalanches may result from a surface avalanche in motion, a cornice fall or a rider finding the sweet spot.

Avoid rock out croppings, large convexities and anywhere the snowpack is thin and/or variable.>Be aware of the potential for large, deep avalanches due to the presence of deeply buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 17th, 2014 2:00PM