Archived

Avalanche Forecast

Dec 2nd, 2016–Dec 3rd, 2016

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Mt Hood.

Watch for left over wind slab on Saturday which may get covered by less cohesive snow Friday night.

Detailed Forecast

West winds will slightly decrease but not let up on Saturday with mostly light snow showers much of the day at Mt HoodÂ and cooler temperatures. Alpine westÂ winds and snow should begin to increase in the afternoon as the next system approaches.

Any shallow wind slab from Friday may linger on Saturday. This is mostly likely on northwest to southeast slopes in the near and above treeline. Watch for firm wind transported or hollow sounding snow. Wind slab from Friday may get covered by less cohesive snow Friday night making it harder to detect the underlying wind slab layer.

Be prepared to change your plans if the next storm begins to arrive and significant snow begins to accumulate sooner than expected on Saturday afternoon.

In most of the lower part of the below treeline bandÂ there is still insufficient snow for avalanches but watch for early season hazards such as terrain traps, rocks and creeks. The shallowest snow is at pass level atÂ Stevens, Snoqualmie and White Passes.

Snowpack Discussion

Another front passed over the Northwest on Wednesday. NWAC stations at Mt Hood had winds generally in the teen to 20Â mph range with variable, very strong gusts. New snow on Thursday morning was around 10Â inches at NWAC stations.

A bit of a break has been seen on Thursday with snow showers tapering at Mt Hood. Another 1-2 inches of new snow was seen at NWAC stations ending Friday morning.

A front is crossing the area on Friday causing moderate to strong south to west alpine winds, with a few inches of snow possible at Mt HoodÂ and a warming trend.

NWAC pro observer Laura Green was at Mt Hood Meadows ski area on Thursday and reported significant wind transport but with minor small wind slab via ski area control results. But wind slab will be deeper in areas not visited by the ski area control crews.

Avalanche Problems

Wind Slabs

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.

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 1