Avalanche Forecast

Archived

Apr 1st, 2018–Apr 2nd, 2018

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Mt Hood.

New snowfall combined with sustained moderate W-NW winds will create dangerous avalanche conditions Monday. Expect to find fresh Wind Slabs on lee slopes near and above treeline. Moderate winds may form Wind Slabs further downslope than usual. You may encounter Storm Slab or Loose Dry avalanches in steep less wind-affected terrain.

Detailed Forecast

Significant new snowfall should accumulate through Monday morning. New snowfall combined with sustained moderate W-NW winds will create dangerous avalanche conditions Monday.

Expect to find fresh Wind Slabs on lee slopes near and above treeline Monday, especially on NW-N-E-SE aspects. Moderate winds may form Wind Slabs further downslope than usual. Use visual clues such as snow drifts, cornices, wind textured snow, and firm snow surface conditions that produce cracks to identify and avoid wind loaded areas. Avoid triggering these avalanches by steering around steep roll-overs, unsupported features, and obvious start zones where you suspect Wind Slabs.

Near and below treeline the new snow is falling on slick or refreezing surface crusts. You may be able to trigger a Storm Slab on slopes over 35 degrees where cohesive new snow slides easily on the old snow surface.

Loose Dry avalanches may release during sunbreaks or can be triggered in steep terrain, running fast above the most recent crust. Recognize exposure to terrain traps where even a small Loose Dry avalanche would have unintended consequences.

Snowpack Discussion

Up to 4 inches of snow accumulated in the Mt. Hood area by 5 pm Sunday with temperatures slowly dropping in the afternoon and moderate W-SW winds reported near and above treeline.

Despite light winds and temperatures in the 30s to lower 40s near and below treeline Saturday, overcast skies for much of the day kept surface snow firm and limited new Wet Loose avalanche activity.

There are currently no significant layers of concern in the mid or lower snowpack.

Observations

On Saturday, Mt. Hood Meadows pro-patrol reported high overcast skies limiting the softening of surface snow on all aspects. No new avalanches were observed.

On Friday, professional reports indicated very little Wet Loose avalanche activity and that rock outcrops had already shed most of their snow.

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.