Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Apr 11th, 2018–Apr 12th, 2018

Alpine
Natural avalanches possible, human triggered probable.
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.

Light snow and moderate winds will create dangerous avalanche danger on wind loaded slopes near and above treeline Thursday. Use visual clues such as fresh cornices, wind drifted pillows and cracks in the snow all indicating that you could trigger a Wind Slab avalanche. Shallow Storm Slabs may build over a newly forming crust. Watch for and avoid deeper drifted snow on steep slopes. Be alert to overhead hazards such as cornices by giving them a wide margin of safety.  

Detailed Forecast

The avalanche danger will shift to new Wind and Storm Slabs building with and after a frontal passage Wednesday night. Further storm showers are expected Thursday. Moderate winds with light to moderate snowfall at cooling temperatures will make triggered slab avalanches likely by Thursday, especially on steep slopes receiving wind transported snow near and above treeline. Use visual clues such as fresh cornices, wind drifted pillows and cracks in the snow all indicating that you could trigger a Wind Slab avalanche.

New Storm Slabs may build over a newly forming crust. Watch for and avoid deeper drifted snow on steep slopes. 

Cooling temperatures will allow for old wet snow to consolidate and refreeze, limiting any Wet Snow avalanches. 

Watch for other spring hazards such as recent cornices along ridges, open glide cracks and opening creeks.

Snowpack Discussion

New wind and snow is arriving at cooling temperatures late Wednesday. This is allowing old wet snow to begin re-freezing while building new Wind and Storm Slab layers.

A front brought rain and wind to Mt. Hood Tuesday. Snow levels fell to around 5500 ft by Tuesday afternoon. Warm and dry conditions were seen on Monday.

The dry weather followed the strong weekend storms that caused rain Saturday to high elevations followed by cooling and new storm snow totaling 1.5-2 ft in the Mt Hood area above 5000 feet through Sunday afternoon. Wet snow avalanches were seen earlier in the storm and continued at lower elevations through the weekend. New Wind and Storm Slabs developed at higher elevations later in the weekend with fresh cornices developing along ridgelines.   

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

Observations

During morning mitigation work Monday, Mt. Hood Meadow Pro-patrol reported that the new snow was not very sensitive to ski triggering. Explosives produced generally shallow soft slabs, with a few that were up to 1-2 ft deep on lee slopes near treeline. 

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.