Avalanche Forecast
Regions: Mt Hood.
Another warm and sunny day with freezing levels above 12,000 feet Tuesday will keep the avalanche danger focused on loose wet avalanches. Steeper solar slopes should be the most likely places for natural or skier triggered loose wet avalanches. Solar slopes involve more than just due south aspects as we head further into February, including east in the morning and southwest to west facing by afternoon.
Detailed Forecast
Another warm and sunny day with light winds is expected again Tuesday. Temperatures pushed into the upper 50's Monday afternoon and it may be a few degrees cooler Tuesday. The avalanche danger will again focus on loose wet avalanches. Steeper solar slopes should be the most likely places for natural or skier triggered loose wet avalanches. Solar slopes involve more than just due south aspects as we head further into February. Â
Be aware of loose wet avalanche potential above terrain traps (like above cliffs or near gullies), where even small wet avalanches can become powerful and have unintended consequences. Â
Lingering wind slab on lee slopes near and above treeline should be stubborn to trigger, but still may be possible in isolated locations on Tuesday.Â
Watch for recent cornices along ridges which may become sensitive to trigger or release naturally during the warm weather.
If pushing higher on the volcanoe Tuesday, the loose wet potential extends well above the top NWAC elevation band with larger avalanches possible. Â
Snowpack Discussion
Weather and Snowpack
A pair of fronts crossed the Northwest on Wednesday and Thursday. NWACÂ stations at Mt Hood for the 2 days ending Friday morning had 18-20 inches of snowfall.
Friday saw a warm system with strong winds bring rain up to near treeline (above 5000 feet) on Mt. Hood before cooling Friday night and depositing about 3 inches of new snow by early Saturday morning.Â
The warmest weather of the season is upon us Monday, Feb. 8th. Temperatures on Mt Hood reached the mid 40's to 50's Sunday and have warmed further Monday, ranging from the lower 50's to near 60! If reached 59 F at 7300 feet Monday afternoon! This is causing significant snowpack settlement, and wet snow conditions, especially on solar aspects by Monday afternoon.
Recent Observations
The Meadows pro-patrol reported little activity Friday with isolated wind or storm slab released by explosives or ski cuts in the near and above tree line.
Large wind slabs were triggered with explosives above treeline by Meadows pro-patrol Saturday morning on lee slopes. Near treeline, cross loaded gullies were sensitive to skier triggering with 1 ft slabs possible. A breakable crust dominated below treeline Saturday. Â
No new reports were received Monday.Â
Avalanche Problems
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1
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: Possible
Expected Size: 1 - 1