Avalanche Forecast
Issued: Mar 15th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Loose Wet.
MBender,
Avalanche Canada
Expect an upward swing in temperatures as the freezing level rises on Monday. This shift in temperature may result in an increased likelihood of triggering persistent slab avalanches. Be especially cautious underneath steep sun exposed slopes and around rock outcrops.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
SUNDAY NIGHT: Mainly clear, light northeast wind, alpine temperature -8 C.
MONDAY: Clear skies, light northeast wind, alpine temperature -1 C, freezing level 1900 m.
TUESDAY: Mix of sun and cloud, light northeast wind, alpine temperature -2 C, freezing level 1700 m.
WEDNESDAY: Mix of sun and cloud, light northeast wind, alpine temperature -3 C, freezing level 1500 m.
Avalanche Summary
Many wind slab avalanches were triggered on Saturday and Sunday. They were most often on southerly aspects and at treeline and alpine elevations. They were rated as small (size 1.5).
Widespread avalanche activity is starting to quiet down on the surface hoar layer described in the Snowpack Summary. Over the past two weeks, small to large (size 1 to 2) avalanches have released on this surface hoar layer. They have most often released between 1800 and 2300 m on northwest to east aspects.
Snowpack Summary
The upper snowpack is relatively complex. Strong northeast wind has formed wind slabs in south to southwest terrain features near ridges. A few different layers of surface hoar and melt-freeze crust exist, which have recently acted as sliding layers. One such layer buried about a week ago may be found about 20 to 40 cm deep. The most widespread layer was buried late February and is now 60 to 80 cm deep. This layer is most commonly found in open trees (e.g. in this MIN) or sheltered terrain around the upper part of below treeline, treeline, and lower alpine elevations. This layer may only remain a concern in the north and east parts of the region.
The remainder of the snowpack is strong and well-settled.
Terrain and Travel
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Extra caution for areas experiencing rapidly warming temperatures for the first time.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Wind slabs were recently formed from strong northeast wind. This wind direction is atypical, so you may find wind slabs in terrain features that don't typically have them. This snow will further load deeper layers, meaning there is potential for step-down avalanche activity.
Aspects: North, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Around 60 to 80 cm of snow overlies a weak layer of surface hoar. This layer has been most problematic on northwest to northeast aspects between 1600 m and 2300 m, but it may exist on all aspects and at all elevations. Assess the layer prior to committing to avalanche terrain or adopt a conservative mindset to avoid the problem.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Wet
The snowpack will undergo a rapid change as the freezing level rises and clear skies prevail. For Sunday, loose wet avalanche activity is most likely during the heat of the day on sun-exposed slopes. Cornices will also weaken with the warming trend.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 16th, 2020 5:00PM
