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

Nov 28th, 2016–Nov 29th, 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.

Fresh wind slab found in the near and above treeline bands will create dangerous avalanche conditions and will be the primary avalanche problem on Tuesday. Look for signs of recent wind loading and don't assume a lack of natural avalanche activity means a slope can't be human triggered! 

Detailed Forecast

A weak front will approach the area Tuesday spreading high clouds over the area in the afternoon. After a cool start Tuesday morning freezing levels should moderate a bit into the afternoon. 

Fresh wind slabs in the near and above treeline bands found mainly on lee easterly aspects will be the main avalanche problem Tuesday. Watch for signs of firmer wind transported snow that indicate wind slab. Storm slabs should be more difficult to trigger and isolated on Tuesday since storm snow instabilities have had time to settle. 

In much of the below treeline band there is not enough snow yet for avalanches.  Avalanche problems should be limited to the upper part of this elevation band.

 

Snowpack Discussion

Weather stations on Mt. Hood picked up 11 and 15 inches at Timberline and Mt. Hood Meadows respectively through early Monday morning with several more inches falling in heavy showers through the daylight hours on Monday. W to NW wind remained moderate on Monday helping to transport new wind to lee easterly aspects. 

The Mt. Hood Meadows pro-patrol found sensitive but soft 6-12" storm slabs on most aspects Monday morning failing within the new storm snow.  Wind slabs averaged 18" on north aspects above treeline with a crust for a bed surface that formed during a warm-up last Friday. 

In general the below tree-line elevation band has plenty of terrain anchors and offers lower avalanche potential due to the shallow snowpack. 

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.