Avalanche Forecast
Issued: Mar 11th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
MBender,
Avalanche Canada
Storm and wind slabs at upper elevations are the main concerns as Tuesday's new snow gets a chance to settle. Look out for the wind to switch direction to the north as cold Arctic air descends into the region.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
WEDNESDAY Night: Cloudy with clear periods and isolated flurries. Moderate to strong northwest wind. Alpine temperature around -13.Â
THURSDAY: Cloudy with sunny periods. Light to moderate north wind. Alpine temperature around -11.
FRIDAY: Mix of sun and cloud. Light to moderate northeast wind. Alpine temperature around -20.
SATURDAY: Mainly sunny. Moderate to strong northeast wind. Alpine temperature around -21.
Avalanche Summary
There was a report of rider triggered size 2 avalanche in the Pine Pass area on Saturday at tree line on a northeast aspect. The fracture was approximately 50-70 cm deep. There was also a report of a snowmobile triggered avalanche in the Mackenzie area on the same day. There are not a lot details regarding these two events, but they were possibly triggered in wind loaded areas. Additionally the fracture depths correspond to the approximate depth of a weak layer of surface hoar that was buried near the beginning of February. This surface hoar may have become more reactive due to the snow stiffening above with wind loading.
Snowpack Summary
20-40 cm of new snow fell in the region between Monday evening and Tuesday night. This has added to 10-20 cm of new snow from last week. Moderate west winds have redistributed the new snow into lee terrain at upper elevations. This all sits on either old wind affected snow, rain crust below 1200 m or sun crusts on south and west facing slopes.
The lower snowpack is strong and well-bonded in many parts of the region. However, given the large extent of the region it remains important to understand snowpack conditions in your local riding area.Â
The Pine Pass and MacKenzie areas have a weak layer of surface hoar roughly 100 cm below the surface that was a problem around treeline elevations in mid-February, but appears have gained strength since then.
The eastern slopes of the Rockies have many shallow rocky slopes that could harbour weak basal facets.
Cornices have grown large and should be given wide berth, especially if you're travelling on ridge lines.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Wind slabs are most reactive during their formation.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Problems
Storm Slabs
20-40 cm new snow from Tuesday fell with with moderate to strong west and southwest winds. Expect wind slabs to develop in the lee of terrain features. In the Pine Pass and Mackenzie areas, storm and wind slabs are possibly adding additional load to a weak layer of surface hoar buried 50-80 cm that may be found at the treeline elevation band.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 12th, 2020 4:00PM
