Avalanche Forecast
Regions: Cascades - North East.
This weather provides a nice opportunity to check out a variety of surface snow conditions but be sure to watch for early season/low snow travel hazards. Also, watch for shallow wet surface snow conditions on some steep sun exposed slopes, especially below rocks or cliffs.
Detailed Forecast
More of the same can be expected on Wednesday: Sunshine and mild temperatures at higher elevations and steep temperature inversions and much colder temperatures accompanied by low clouds at lower elevations/valleys throughout the east slopes of the Cascades.
This weather provides a nice opportunity to check out a variety of surface snow conditions but be sure to watch for early season/low snow travel hazards. Early season terrain hazards include poorly covered rocks, vegetation and creeks, particularly at lower elevations.
Also, watch for shallow wet surface snow conditions on some steep sun exposed slopes, especially below rocks or cliffs.Â
Snowpack Discussion
Strong high pressure has now been over the region for over a full week. Sunshine and very mild temperatures have been seen at higher elevations with steep temperature inversions and much colder temperatures accompanied by low clouds at lower elevations/valleys throughout the east slopes of the Cascades. This weather has allowed for overall strengthening and consolidation of an already strong snowpack. The snowpack is well consolidated with settled old storm snow of about 1 to 2 feet over the strong Thanksgiving rain crust. East-side snowdepths are highest in the Washington Pass area and lowest in the southeast zone.Â
No human-triggered avalanches have been reported in over a week. Some natural small loose wet slides have occurred on mainly steep sun exposed slopes over the last week, but have become much less frequent over the past several days. Active wind loading has not been observed since late last week.Â
Surface conditions are highly variable. On solar aspects, surface melt-freeze crusts reform every night. On shaded and sheltered aspects, settled storm snow is still providing some nice skiing and riding conditions. Many aspects in higher terrain now feature wind stiffened snow. Near surface faceting and large surface hoar growth has been reported on colder, non-solar aspects throughout the Cascades but especially in the Washington Pass area. These persistent grain types will become important when snowfall returns and watched as potential future weak layers.Â
The snowpack is well consolidated and strong with settled old storm snow of about 1-2Â feet bonded well to the strong Thanksgiving rain crust.Â
Observations
North
NCMG was in the Washington Pass area on Monday and observed isolated pockets of wind slab to be generally unreactive. No weak layers were noted in the upper snowpack and widespread and large surface hoar was observed near and below 6000' in non-solar, open terrain.Â
Central
No recent observations.
South
No recent observations.
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.
Elevations: All elevations.
Likelihood: Unlikely
Expected Size: 1 - 1