Avalanche Forecast
Issued: Mar 4th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Wind Slabs and Persistent Slabs.
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Avalanche Canada
Warm temperatures and sunshine will elevate avalanche conditions across the region. Conditions in the northern end of the region (e.g. Quartz Creek and Dogtooth Range) are most concerning given recent avalanche activity. Stick to low angle shaded terrain.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
Temperatures gradually cool as the ridge of high pressure breaks down.
THURSDAY NIGHT: Clear skies, moderate southwest wind, a weak temperature inversion may develop overnight with alpine temperatures in the -2 to 0 C range and cooler in the valleys.
FRIDAY: Mostly sunny with some afternoon clouds, moderate south wind, freezing level around 2100 m with treeline temperatures near 0 C.
SATURDAY: Cloudy with scattered flurries and up to 5 cm of new snow, light southwest wind, freezing level climbs to 1700 m with treeline temperatures around -3 C.
SUNDAY: Mix of sun and cloud with isolated flurries, light wind, freezing level around 1300 m with treeline temperatures near -5 C.
Avalanche Summary
Preliminary reports from Thursday suggest there were some wet loose avalanches on sun-exposed slopes. On Friday the primary concern is natural avalanches on steep sun-exposed slopes. These will most likely present as wet loose avalanches, but larger wind and persistent slab avalanches are also possible. Read the latest Forecaster Blog for concerns about the warming.
Over the past week there have been several notable reports of large human triggered persistent slab avalanches in the Dogtooth Range and Quartz Creek area. This includes a remotely triggered size 2 avalanche on Tuesday on a northwest slope at 2100 m that failed on a 40 cm deep weak layer (MIN report), a size 3 human-triggered avalanche on Feb 27 on a east-facing alpine slope (MIN report), a size 2 avalanche on Feb 27 on a south-facing slope (MIN report), and a few remotely triggered size 2 avalanches on Feb 24 (MIN report).
Snowpack Summary
Rising freezing levels and sunshine will be melting, and potentially destabilizing, snow surfaces the next few days. Higher elevations have been impacted by recent wind from the southwest, likely leaving wind slabs lurking on shaded north and east slopes.
Persistent weak layers have been most active in the northern end of the Purcells where a buried layer of surface hoar that formed in late January is 40-80 cm deep and an older surface hoar layer is 60-120 cm deep at treeline. These layers may exist as a combination of facets and crusts at other elevations. Recent observations suggest these layers have been less problematic as you move further south.
Steep rocky areas where the snowpack is thin likely has addition weak layers near the base of the snowpack.
Terrain and Travel
- Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
- Choose gentle slopes without steep terrain above.
- Caution around convexities or sharp changes in terrain.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Loose Wet
Wet loose avalanches may release naturally on steep sun-exposed slopes.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Reactive wind slabs likely exist in steep open terrain at alpine and treeline elevations, especially on north and east aspects.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Persistent slab avalanches are most likely in the northern Purcells where there has been recent avalanche activity on a 40-80 cm deep layer of surface hoar, facets, and/or crusts (see Avalanche Summary).
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 5th, 2021 4:00PM
