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Avalanche Forecast

Archived

Feb 14th, 2016–Feb 15th, 2016

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

Regions

Olympics.

The continued warm wet weather Monday will maintain wet snow conditions near and below treeline. New wind slabs and cornices should maintain dangerous avalanche conditions above treeline Monday. 

Detailed Forecast

Moderate to occasional heavy rain and snow is expected with high freezing levels, between 6-7000 feet in the Olympics Monday. Winds should be very strong Monday.

Many steep slopes may have released naturally by Monday, locally lowering the danger on those slopes, however on slopes that have not released due to warming and additional load, natural or triggered avalanches should be possible Monday.   

Wind slabs should build on lee slopes below ridges at the higher elevations, above treeline.

Watch for fresh cornices along ridges and stay well clear.

Snowpack Discussion

Weather and Snowpack

A large upper ridge over the West Coast  led to the warmest weather of the winter last Sunday through Wednesday. During this stretch, temperatures were well above freezing.  Cooling Friday and light snowfall late Friday through Saturday deposited about 8 inches of storm snow. Warming Sunday turned snowfall to rain once more at Hurricane Ridge with temperatures rising into the upper 30's and climbing Sunday afternoon.

The recent storm snow has consolidated and become wet snow by Sunday. The latest storm snow overlies the melt-freeze crust formed Friday afternoon after the recent warm weather. The underlying snow is well settled and homogenous.

Professional NWAC observer, Matt Schonwald was at Hurricane Ridge on Friday. Recent warmth and persistent winds have generally created a dense and homogeneous snowpack without any layers of concern. In the Hurricane Ridge area the snowdepth falls off rapidly below 4400 feet. Bare patches or thin snow cover is widespread along ridgelines and south through west aspects. Matt and an NPS ranger did observe 2 glide avalanches that likely occurred Thursday night. The larger one, size D2, released in the June 20th path down to a gravel bed. However, except in isolated terrain features, glide avalanches should not be a widespread concern in the Hurricane Ridge area. 

Problems

Wind Slabs

Wind Slab avalanches are the 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.

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.