Avalog
Register
Get forecast notifications
Create an account to receive email notifications when forecasts are published.
Register
Login
Archived

Avalanche Forecast

Jan 31st, 2017–Feb 1st, 2017
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Mt Hood.

East winds will begin to redistribute loose surface snow to lee westerly aspects Wednesday near and above treeline. Shallow new wind slab may become particularly touchy in areas where it bonds poorly to an underlying crust. All aspects are listed to cover older wind slab formed over the last few days.  

Detailed Forecast

East winds will begin to redistribute loose surface snow to lee westerly aspects Wednesday near and above treeline. Shallow new wind slab may become particularly touchy in areas where it bonds poorly to an underlying crust. All aspects are listed to cover older wind slab formed over the last few days.

Snowpack Discussion

Weather and Snowpack

An atmospheric river arrived Tuesday 1/17 with rain up to about 7000 feet on Mt. Hood. From Thursday 1/19 through Sunday 1/22, generally 15-20 inches of snow accumulated at NWAC Mt Hood stations.

A large upper ridge and warm air mass built over the Northwest last Thursday to Saturday. By Saturday temperatures had reached the 40's.

A front crossed the Northwest Sunday afternoon causing moderate southwest winds, slight cooling and no measurable precipitation through Monday morning. Westerly winds above treeline were strong Monday night through Tuesday morning with occasional periods of light snow. 

Recent Observations

The Mt. Hood Meadows pro-patrol reported little in the way of avalanche activity over the last few days but did note a thin melt-freeze crust up to 6600 feet Monday morning along with some wind transport of previous snow that had occurred above 6500 feet Sunday. 

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: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 1