Avalanche Forecast

Archived

Feb 7th, 2016–Feb 8th, 2016

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 unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Mt Hood.

A warm and sunny day with freezing levels pushing above 12,000 feet Monday will point the avalanche danger toward loose wet avalanches. Steeper solar slopes near and above treeline should be the most likely places for natural or skier triggered loose wet avalanches. Solar slopes involve more than just due south aspects as we head further into February.

Detailed Forecast

A warm and sunny day with lighter alpine winds should be seen on Monday. As freezing levels push above 12,000 feet, the avalanche danger will focus on loose wet avalanches. Steeper solar slopes near and above treeline should be the most likely places for natural or skier triggered loose wet avalanches. Solar slopes involve more than just due south aspects as we head further into February.

The hazard should be locally lower below treeline in areas affected by cool easterly winds and in areas above treeline with dense wind pack.

Be aware of loose wet avalanche potential above terrain traps (like above cliffs or near gullies), where even small wet avalanches can become powerful and have unintended consequences.

If pushing higher on Mt. Hood Monday, the loose wet potential extends well above the top NWAC elevation band with larger avalanches possible.

Lingering wind slab on lee slopes near and above treeline should be stubborn to trigger, but still possible in isolated locations on Monday.

Snowpack Discussion

Weather and Snowpack

Cool and benign weather settled over Mt. Hood Sunday to Tuesday with ample sunshine on Tuesday. A sun crust likely formed on solar slopes.

A cold front and then a warm front crossed the Northwest on Wednesday and Thursday. NWAC stations at Mt Hood for the 2 days ending Friday morning had 18-20 inches of snowfall.

Friday saw a warm system with strong winds bring rain up to near treeline (above 5000 feet) on Mt. Hood before cooling Friday night and depositing about 3 inches of new snow by early Saturday morning.

Mostly sunny skies allowed temperatures to push into the 40s and even 50s on Mt. Hood Sunday with winds rapidly falling off during the day.

Recent Observations

The Meadows pro-patrol reported little activity Friday with isolated wind or storm slab released by explosives or ski cuts in the near and above tree line.

Large wind slabs were triggered with explosives above treeline by Meadows pro-patrol Saturday morning on lee slopes. Near treeline, cross loaded gullies were sensitive to skier triggering with 1 ft slabs possible. A breakable crust dominated below treeline Saturday.

No new reports were received Sunday.

Problems

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.

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.