Wind Slabs
N
NE
E
SE
S
SW
W
NW
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1–3
New snow and wind on Sunday night will form fresh and reactive wind slabs. Watch for triggering in the lee of ridge crests and terrain breaks.
Avalanche forecast
View on mapSouth Rockies
Jan 4 – 5, 2015Avalanche Canada
Archived · expired 12 years ago
Avalanche danger
Tue
Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
Highlights
Sunday night's forecast snowfall amounts are uncertain. Pay close attention to how much snow falls (and how hard the wind blows) as wind slabs are the primary concern.
Avalanche problems
Persistent Slabs
NNEESESSWWNW- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–4
A crust which formed in December should remain on your radar as it has the potential to produce large avalanches. Dig down and test weak layers before committing to a line.
Confidence
Fair - Intensity of incoming weather systems is uncertain on Sunday
Weather Forecast
A frontal wave will move over the South Coast, and track eastward just south of the boarder. This pattern is forecast to bring generally light snowfall to the region by Monday morning. Light snowfall is expected to continue throughout Monday night and into Tuesday morning. By Tuesday afternoon, a drying trend will develop and carry into Wednesday. Remnant arctic air will keep freezing levels at valley bottom; however, an inversion is likely on Wednesday with above-freezing alpine temperatures. Ridgetop winds should remain mainly westerly until Wednesday. They are forecast to hit extreme values on Sunday night and Monday morning, and then remain mainly moderate to strong for the rest of the forecast period.
Avalanche Summary
No new avalanches have been reported, although I suspect there was some wind slab activity in response to Friday's wind event. I expect another round of wind slab activity with new snow and wind forecast for Sunday night.
Snowpack Summary
Snow surfaces are variable with northerly, wind exposed aspects showing firm wind pressing, or a scoured exposed crust. More sheltered locations have up to 30 cm of low density, faceted snow. In the alpine and at treeline, strong northerly winds have transported this snow into stiff wind slabs on opposite slopes. Up to 70 cm below the surface you will likely find a hard, thick crust which formed mid-December. At higher elevations this crust has facets (sugary) snow above it and well-preserved surface hoar up to 10 mm in size in sheltered locations at treeline and below. Where the crust exists, it may be bridging triggers from penetrating to deeper persistent weaknesses. However, on high alpine slopes above where the rain crust formed, or in areas where rain didn't occur, deeply buried facets may still be susceptible to triggering, especially in thinner snowpack areas.