Avalanche Forecast
Regions: Mt Hood.
Travel in avalanche terrain is not recommended at Mt Hood on Monday.
Detailed Forecast
Strong west flow will carry a strong cold front across Mt Hood on Monday. This should cause strong alpine winds with moderate to heavy snow and a warming trend. The warming trend should contribute to the formation of both new wind slab and new storm slab layers.
New wind slab is very likely at Mt Hood on Monday. Wind transport will deepen these layers mainly on lee north to southeast slopes but wind slab is possible on other aspects.
New storm slab is also very likely at Mt Hood on Monday on any slopes that rapidly accumulate new snow of more than a several inches.
Travel in avalanche terrain is not recommended at Mt Hood on Monday.Â
Another strong front should be seen Monday night and Tuesday. This should maintain or increase the avalanche danger in the Olympics and Cascades.
Snowpack Discussion
Weather and Snowpack
The last storm cycle to affect all of the Olympics and Cascades was from Thursday, December 8th through Monday morning, December 12th. About 4 feet of snow were recorded at the NWAC stations in the Mt Hood area.
Another system moved across the Mt Hood area late Wednesday through Thursday morning depositing an additional foot of new snow with moderate southeast winds shifting to the west and decreasing.Â
There has been a lot of snowpack settlement since the last storm cycle ended, allowing this underlying snow to mostly stabilize.
Clear or fair and cold weather has been seen about Thursday at Mt Hood. This should have caused new widespread surface hoar and near surface faceted snow to develop to develop at Mt Hood as in the Cascades. Thin sun crusts have also formed on steeper solar slopes. These layers are expected to act as widespread weak layers or sliding surfaces for the upcoming moderate to heavy snowfall.
Recent Observations
NWAC pro-observer Laura Green was out in the Newton and Clark drainages on Friday a found a mix of surface conditions of recent snow and 3-4 mm surface hoar with a thin sun crust on solar slopes. The upper snow pack on N-NE slopes was right side up with no direct signs of instability.
A report via the NWAC Observations tab also indicated a small slab avalanche near the Ski Bowl ski area on Friday.
The Mt Hood Meadows pro-patrol on Sunday reports fairly widespread surface hoar and near surface faceted snow up to about 7300 feet. Calm winds have allowed it to develop or grow the past couple days.
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: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Very Likely
Expected Size: 1 - 1
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. 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.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 1