Avalanche Forecast
Regions: Cascades - North East.
The avalanche danger will increase by Wednesday morning. You may be able to trigger large avalanches in the new snow especially at upper elevations. Check how well the new snow is bonded to old surfaces, and use caution on slopes steeper than 35 degrees if you find recent snow that slides easily.
Discussion
Incoming weather will be the main factor affecting Wednesday's avalanche danger. Over the next 48 hours, you can expect dynamic storms with gusty southwest winds, waves of moderate to heavy precipitation, and swings in temperature. With snow levels rising to 3,000ft on Wednesday, you may find some moist snow and even small wet avalanches at low elevations.
On Monday, observer, Mark Allen, toured in the Rattlesnake and Robinson drainages and found a shallow and weaker snowpack compared to areas closer to Washington Pass. Snow depths ranged from about 4 feet at lower elevation to about 5 feet at mid-elevations. A notable layer of well-developed facets lies about 2 feet below the surface and is more prominent than in the eastern portions of the zone. It'll be a good idea to keep and eye on this strong-over-weak structure as rain moves in later in the week.
Snowpack Discussion
New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.
Avalanche Problems
Storm Slabs
Storm slabs could be about 1 foot deep by Wednesday. You may find drifts that formed at upper elevations with gusty southwest wind Tuesday night. The likelihood that you'll be able to trigger these avalanches will be determined by the bond between new and old snow. Snow will fall on a variety of old snow surfaces, including moist snow and a recent crust buried around MLK weekend. Dig below the new snow to check for a possible poor bond.
Use small test slopes and quick snowpack tests to see if the snow slides easily on the old surface. Watch for fresh avalanches and cracks shooting through the snow. If you see these red flag warning signs, use caution on steep roll-overs and slopes steeper than 35 degrees. Avoid terrain traps where even a small avalanche could have serious consequences.
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: Likely
Expected Size: 1 - 1