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Avalanche Forecast

Archived

Jan 31st, 2016–Feb 1st, 2016

Alpine
Natural avalanches unlikely, human triggered possible.
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 greatest avalanche problem should be wind slab on lee slopes near and above treeline mainly N-SE facing slopes. Watch for signs of firmer wind transported snow.

Detailed Forecast

Light winds, cloudy or mostly cloudy weather, a few light snow showers and cool temperatures should be seen at Mt Hood on Monday.

This weather should bring a further gradually decreasing avalanche danger on Monday.

The greatest avalanche problem should be wind slab on lee slopes near and above treeline mainly N-SE facing slopes. Watch for signs of firmer wind transported snow.

Watch for storm slab in areas that had rapidly accumulating snowfall. Storm layers that may exist above the new crust will slowly settle but could remain reactive to human triggers mainly near and above treeline.

Continue to evaluate snow and terrain carefully on Monday.

Snowpack Discussion

Warm wet weather will have caused increasing wet snow conditions at Mt Hood Wednesday-Thursday.

A strong occluded front with strong winds crossed the Northwest on Friday. NWAC stations at Mt Hood had about a foot of new snow by Saturday morning. About another 6-8 inches followed at the tail by Sunday morning.

Some areas have reported a strong bond of the new snow to the new crust and some a poor bond depending on if the new snow arrived after cooling began. There have also been sensitive storm layers reported within the new snow which will take a bit of time to gradually stabilize.

NWAC pro-observer Laura Green in the Clark-Mitchell-Heather Canyon areas reported building wind slab and building cornices on Friday.

The Mt Hood Meadows pro-patrol Saturday reported mainly 4-8 inch storm slab released by ski cuts in the above tree line.

A report via the NWAC Observations page for Pea Gravel Ridge on Saturday reported building 4-6 inch wind slab on lee slopes near ridges. Storm layers and storm slab was also noted.

Today the Mt Hood Meadows patrol reported limited 4-6 inch wind slab on lee slopes in the above tree line, lower than usual below ridges, which would be small and difficult for a skier to trigger.

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.