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

Mar 16th, 2015–Mar 17th, 2015

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

Regions

.

It's nearly spring and the sun's strength can rapidly create locally dangerous conditions on steeper solar slopes, where even a shallow and slow moving avalanche would be powerful and could force you into unintended terrain traps. Also, watch for weakening cornices along ridges during the warmer part of the day.

Detailed Forecast

A weak weather system Tuesday should cause cloudy conditions with light rain or snow at times. Only light amounts of new snow are expected and this should not cause a significant increase in danger.   

The avalanche danger will be regionally higher along the east slopes in the northeast Cascades. 

Due to the low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation. Many areas below treeline do not have enough snow to cause an avalanche danger.

Snowpack Discussion

The latest installment of warm and dry weather lasted from early to mid-March and led to more snowpack consolidation and a scarcity of avalanche activity. Snowdepths vary greatly across the east slopes... with a regionally healthy snowpack in the northeast Cascades to bare solar and low elevation slopes for the central and southeast Cascades.   

Over the weekend, an atmospheric river brought a one-two punch to the Pacific Northwest. Saturday's event brought up to 1.0 inches of water with a snow level around 6500 ft through Saturday afternoon, with much lower totals in the Blewett-Mission Ridge area. 

Another inch of water fell more evenly along the east slopes Sunday, with the snow level 6000 feet in the south and 4500-5000 feet in the north.  Around 15 inches fell at the NWAC Washington Pass and the Hart's Snotel through early Monday.

NWAC observer Jeff Ward was in the Hart's Pass area of the northeast Cascades over the weekend and reported touchy yet small loose wet near treeline and growing storm and wind slab concerns by late Saturday afternoon. By late Sunday in the NE zone, there was an average of 16 inches of storm snow with a few small triggered slides reported, both size one, one a dry loose the other a small slab. 

No reports were received in the central and south zones, but likely the storm snow amounts received over the weekend were less than the NE zone.

Problems

Loose Wet

Loose Wet avalanches are the 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. 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.

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.