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

Feb 26th, 2016–Feb 27th, 2016

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Mt Hood.

Mostly small, shallow areas of new wind and storm slab will be possible on Saturday near and above treeline. Avalanche problems would be greater if there is more new snow than expected.

Detailed Forecast

Rain or snow should change to showers Friday night with lower snow levels. Light showers mainly along the west slopes should end on Saturday.

This weather should bring a couple to a few inches of snow near and above treeline along the west slopes with a cooling trend. The cooling trend with rain changing to snow mainly in the near and above treeline should help bond new snow to previous snow.

New small areas of mostly shallow wind slab will be possible on isolated lee slopes. This should be mainly N to E slopes near and above treeline. Watch for firmer wind transported snow.

Isolated older wind slab from E-SE winds Monday night and Tuesday may also linger on unusual W aspects.

Small areas of shallow storm slab will also be possible if any areas receive a few inches of rapidly accumulating snowfall.

These avalanche problems would be greater if there is more new snow than expected.

Snowpack Discussion

Weather and Snowpack

The last storm cycle  occurred late last week when about 2 feet of snow fell from the 17th-20th. Some cornices and wind slabs formed during this period with triggered wind slabs reported last weekend.

Strong E-SE crest level winds in many areas Monday night and Tuesday of this week, redistributed surface snow and built new localized wind slabs on unusual west facing slopes. Some of these wind slabs were touchy earlier this week, but have stabilized quickly under the warm weather.

Springlike weather under high pressure Wednesday and Thursday caused abundant sunshine with temperatures climbing into the upper 40's to mid 50's Thursday afternoon! 

This fair and mild weather has allowed for melt-freeze crust formation overnight and varying amounts of wet surface snow depending on slope aspect, during the warmest part of the day.

The mid and lower snow pack along the west slopes should be a stable mix of crusts and layers of moist and rounded snow crystals.

Recent Observations

Reports from the Mt Hood Meadows pro-patrol on Wednesday indicated a generally stable snowpack with morning crusts and afternoon wet snow conditions on solar aspects. Near and above treeline, stiff wind affected sastrugi was reported.

The pro-patrol on Thursday reported only a draining saturated upper snow pack and no avalanches.

 

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.