Avalanche Forecast

Archived

Jan 23rd, 2019–Jan 24th, 2019

Alpine

Natural avalanches possible, human triggered probable.

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, human triggered possible.

Regions

Mt Hood.

The Bottom Line: Large and dangerous wind slabs likely formed above treeline Tuesday night and Wednesday. Give time for conditions to stabilize on the upper mountain by avoiding steep wind loaded terrain and by limiting your exposure to large open avalanche paths that begin higher on the mountain. Near and below treeline, think about the increasing potential for loose wet avalanches if the sun pops out on steep, sunny slopes.

Snow and Avalanche Discussion

After an initial bout of snow, a strong frontal system pushed heavy rain up to at least 6500-7000 ft Tuesday night and Wednesday morning in the Mt. Hood area. Strong west winds also rocked the mountain during this period, limiting direct observations from the upper mountain on Wednesday. As we head into Thursday, we will likely be dealing with two sets of problems; hard wind slabs above the rain-line in the alpine and loose wet avalanche potential near and below treeline.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.