Storm Slabs
N
NE
E
SE
S
SW
W
NW
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1–2
At elevations where precip falls as snow, storm slabs will be especially reactive where they sit over a layer of surface hoar crystals.
Avalanche forecast
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Dec 4 – 5, 2023Avalanche Canada
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Avalanche danger
Wed
Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
1 · Low
Highlights
Avalanche danger will increase Monday as heavy snow and rain add significant load to the meagre snowpack. Minimize your exposure to avalanche terrain.
Avalanche problems
Loose Wet
NNEESESSWWNW- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 1–2.5
Loose wet avalanches will become increasingly likely on Monday as heavy rain soaks the snowpack.
Confidence
Moderate
Avalanche Summary
We are expecting a natural avalanche cycle as the storm intensifies on Monday.
On Saturday, natural and remotely triggered storm slab avalanches size 1-2 were reported near Whistler, and MIN reports from Cypress, Anif and Red Heather describe whumphing and easy failures in snowpack tests. If you're heading out in the backcountry, please consider sharing any observations on the Mountain Information Network 🙏
Snowpack Summary
Below 1800 m, rain soaks the snowpack, while heavy storm slabs build above. The upper snowpack consists of 30-60 cm of snow from the previous storm, which sits over various layers of crusts and old faceted snow, or directly on the ground. In sheltered areas, the recent snow may also contain a layer of large surface hoar crystals which we are hoping for the rain to eliminate. The snowline is likely creeping up as rain washes away lower elevations.
Check out the photos and snowpack description in this MIN from our forecaster field trip to Round Mountain on Sunday!
Weather Summary
A warm, wet storm arrives on Monday, culminating Monday night with heavy precip and positive temperatures up to 3000 m. Very heavy precip like this can bring the snow line several hundred meters below freezing level, so expect a mix of snow and rain. Things start to cool off again on Tuesday.
Sunday night
5-10 cm of new snow. Moderate southwest ridgetop wind. Freezing level 1300 m.
Monday
Mixed precip (25-50 mm). Strong south ridgetop wind. Freezing level spiking to 3000m, snow level around 1800 m.
Tuesday
Heavy precip overnight (50-90 mm), easing and becoming snow in the morning (10-20 mm). Strong southerly ridgetop wind easing to moderate southwest. Freezing level dropping from 3000 m to 1500 m.
Wednesday
A mix of sun and cloud. Calm. Freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
- Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.