Avalanche Forecast

Archived

Jan 4th, 2015–Jan 5th, 2015

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Olympics.

Dangerous avalanche conditions are expected Sunday night and Monday and travel in avalanche terrain near and above treeline is not recommended.

Detailed Forecast

Moderate to heavy rain should reach up into the above treeline elevation band through Monday. This will orient the avalanche type toward wet slab and wet loose. Rain should quickly load snowfall received earlier in the storm and result in widespread natural loose wet avalanches especially in steeper terrain. Natural wet slabs, mainly on lee aspects near and above treeline, have the potential to be larger and more destructive. Due to low snow cover, the avalanche danger will quickly decrease in the below treeline band at lower elevations.

Snowpack Discussion

On Saturday, NWAC pro-observer Katy Reid confirmed a 3 cm graupel layer at 10 cm below the surface on E-NE aspects near and below treeline. This layer could become reactive during the upcoming storm. Otherwise, the Hurricane Ridge area did not have many concerns heading into the weekend storm.

On Sunday light snow accumulated at Hurricane Ridge with rising temperatures and strong south transport winds leading to inverted new snow layering and new wind slab. Snow turned to rain at Hurricane Ridge late Sunday afternoon. Moderate to heavy rain should continue Sunday night.

Problems

Wet Slabs

Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

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.