Avalanche Forecast

Issued: Mar 14th, 2014 11:19AM

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

ghelgeson, Avalanche Canada

Cariboos.

You don't often see three problems in a forecast, but we don't often deal with a snowpack this complex. Professionals are running a tight and conservative ship right now, I recommend that you do the same.

Summary

Confidence

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

Weather Forecast

Synopsis: Sunny skies are great and all, but were transitioning back into winter this weekend. Saturday offers cloud cover, but we shouldn't see much precip until late in the day when it begins to snow and blow out of the SW. Snow should continue through the night and into Sunday before tapering off in the wee hours of Monday morning. At that time the flow switches to the NW and we should see some ridging build in early next week.(If you see this format X - (Y) - Z Then X - Z shows the probable range with Y being my best guess.)Saturday: Freezing Level: 1000m - (1300m) - 1700m; Precip: 2:4mm - 2:5cm (mainly late in the day); Wind: Moderate, S | Extreme SW at ridgetop.Saturday Night: Freezing Level: 900m - (1200m) - 1700m; Precip: 8:15mm - 10:25cm; Treeline Wind: Strong, SW | Extreme SW at ridgetop.Sunday: Freezing Level: 1300m - 1500m; Precip: 3:4mm - 5:10cm; Treeline Wind: Strong, SW | Extreme SW at ridgetop.Monday: Freezing Level: 900m - 1000m; Precip: Trace; Treeline Wind: Strong, NW

Avalanche Summary

No new avalanches to report from Thursday, but adjacent regions reported on going natural and rider triggered large avalanches.On Wednesday riders remote triggered avalanches to size 2 on steep NE facing slopes at treeline. One natural size 3 on a relatively steep NE facing bowl feature was also observed, likely failing on the February 10th PWL.The group involved in a very close call with a size 3.5 avalanche in the Ozalenka Valley south of McBride submitted a great incident report. Check it out here.

Snowpack Summary

The surface is currently a mix of 3/6mm surface hoar and crust. Last weeks storm snow has settled into a 50cm - 80cm slab that rests on the early March interface consisting of small grained surface hoar in sheltered areas and a sun crust on solar aspects. In upper elevation wind exposed terrain the new snow has been pushed into deep wind slabs by moderate SW winds.The last week featured an average daytime freezing level around 1500m which resulted in a daily melt freeze cycle that left many features wet and sloppy by the afternoon. This setup resulted in some serious incidents recently.Ridgetop cornices remain large and unsupported.The February 10th surface hoar/facet/crust combo is 90cm - 160cm 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

Persistent Slabs

50 - 100 cm of settled old storm snow has coalesced into a slab that is sitting on the March 02 suncrust / surface hoar combo.

The snowpack still needs time to adjust to the recent warm temps and rain. Keep it reined in.>Given all the uncertainty surrounding this slab, I advise against stepping out into terrain with any kind of consequence.>Terrain at and below treeline is capable of producing large destructive avalanches. The trees are not the safe-haven they normally are at this time.>Watch for terrain traps where debris could accumulate into very deep deposits.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

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

Storm Slabs

When it starts snowing late in the day, the new snow will come to rest on a surface hoar/crust combo. This interface will likely be quite reactive throughout the storm.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Account for a potentially reactive storm slab in your travel plans. You don't want to get surprised by changing conditions late in the day.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 15th, 2014 2:00PM