Avalanche Forecast

Issued: Mar 7th, 2014 8:24AM

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

Avalanche Canada jcoulter, Avalanche Canada

Check out the South Rockies Blog and Forecaster Blog for more information on current snowpack and avalanche conditions.

Summary

Confidence

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

Weather Forecast

The ridge of high pressure shifts inland by Friday night pushing out the last of the patchy moisture. Generally dry conditions with some sunny breaks expected for Saturday morning, but clouds and increased winds will return by the evening as the large pacific frontal system approaches. Moderate to heavy precipitation is expected overnight on Saturday and Sunday morning, with a chance of freezing levels dropping slightly sometime on Sunday with the passage of a cold front.Overnight Friday: Trace of new snow, cloudy, moderate south west winds, with freezing levels between 1200-1400m.Sat: Trace of new snow for the day, increasing west winds (gusting to strong) by late afternoon. Heavy snow/rain expected overnight on Sat with freezing levels 1800-1900m.Sun: Morning snow/rain, heavy at times, easing during the day, moderate (gusting to strong) south west winds, freezing levels 1900-2100m, but possibly dropping later in the day.Mon: Trace of precipitation possible, light winds, freezing levels 1700m

Avalanche Summary

Avalanches in clearcuts, road banks, lower angle terrain and non obvious avalanche paths continue to surprise backcountry enthusiasts throughout the region so consider them carefully in your travel plans.Two recent avalanches on east aspects, size 2.5-3 were noted by the field team in the Crowsnest pass today.In the Harvey Pass area there was a widespread natural cycle on Thursday with some avalanches up to size 3. Most avalanches are failing at the storm snow interface, but some are initiating or stepping down to the February 10th persistent weak layer, even in surprisingly low angle and gladed terrain.There was a report of a large avalanche in Thursday's cycle hitting the grooming about 4km before the Rolling Hills cabin near Fernie.On Thursday the South Rockies team reported a size 2.5 avalanche out of a north facing chute near Grave Lake that left 6 meters of debris on a logging road, blocking their return to the trucks.

Snowpack Summary

Some areas of the South Rockies (Elk Valley South and Flathead) received Thurday's precipitation as significant rain event below 1500m-1700m. In areas above 1600m there is approximately 40-70cm of new storm snow sitting on top of the March 2 interface consisting of surface hoar, facets or a crust depending on your aspect and elevation . Moderate to strong SW winds combined with the new snow have created windslabs in lee features and have likely contributed to cornice growth at upper elevations.The mid pack still contains a layer of facets and/or surface hoar that is now down between 70-180cm depending on your location in the South Rockies. It is still showing good fracture character on snowpack tests, suggesting that it may be possible for storm slabs to step down to this persistent weak ness.  Check the South Rockies Blog for the latest snowpack discussion.

Problems

Storm Slabs

An icon showing Storm Slabs
A large load from recent snow and rain has settled into a slab and is sitting on a weak layer buried in early March. SW winds have created windslabs in lee areas and contributed to cornice growth.
Caution required around loaded road banks, cutblocks and other non obvious avalanche terrain>Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Wet Slabs

An icon showing Wet Slabs
Loose wet slides are also possible in areas where rain soaked snow has lost its cohesion.
Avoid steep unsupported terrain below treeline especially if the snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Storm slabs in motion have the potential to step down and trigger a persistent weak layer that is now buried between 100-170cm deep.
Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>Use conservative route selection, resist venturing out into complex terrain even if you observe no obvious signs of unstable snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Mar 8th, 2014 2:00PM