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Avalanche Forecast

Archived

Apr 8th, 2015–Apr 9th, 2015

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Columbia.

Direct sun & warmth are currently the primary drivers of hazard and the weather forecast indicates that Thursday will be quite warm. Minimize your exposure to large slopes if the snowpack is becoming moist or wet.

Confidence

Fair

Weather Forecast

THURSDAY: Freezing level starting at 1200m, rising to 2200m. Light W/NW winds at all elevations. No significant precipitation expected. Clear skies.FRIDAY: Freezing level holding at 1800m. Moderate S/SW winds at treeline, strong S/SW winds at ridge-top. No significant precipitation expected. Cloud cover rapidly building to overcast by lunch.SATURDAY: Freezing level hovering around 1500m. 2 to 8mm precipitation, 2 to 15cm of snow possible. Moderate SW winds at treeline, strong SW winds at ridge-top.

Avalanche Summary

Observations from Sunday, Monday and Tuesday were limited to power sluffing from steep high elevation terrain and small loose wet activity.

Snowpack Summary

Surface faceting is beginning to work on the 15 to 45 cm generated by convective snow fall over the weekend. This snow remains dry on high elevation north facing features, but is moist almost everywhere else. Just below this snow you'll find tired old wind slabs at upper elevations and the supportive late-March crust that is thought to exist up to around 2100m. Moist snow underneath the late-March crust is ubiquitous in most of the region.Two significant persistent weak layers composed of crust and facets exist in the snowpack. Mid-March is down 40 to 80cm below the surface and Mid-February is down 80 to 140cm. Observations indicate that there is significant faceting occurring between the two crusts. While avalanche activity on these weak layers has tapered off snowpack tests indicate that these layers may still be sensitive to triggering.

Problems

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.