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Avalanche Forecast

Archived

Jan 20th, 2016–Jan 21st, 2016

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

Regions

Olympics.

Loose wet avalanches will become likely on Thursday due to rainfall. Loose wet avalanches are likely to be small and confined to steeper slopes in all elevation bands in the Hurricane Ridge area. Be especially wary near terrain traps, where even a small avalanche could have unintended consequences. Larger and more dangerous avalanches are more likely outside the Hurricane Ridge area on the SW slopes of the Olympics due to heavier rain.

Detailed Forecast

A warming trend will begin Wednesday night and continue on Thursday as a frontal system stalls offshore. Heavy rain and strong winds will buffet all elevation bands in the Olympics Thursday. 

Storm instabilities have likely settled out with only minor accumulations this week and mild temperatures. There may be some stubborn wind slab on lee slopes near and above treeline. 

Loose wet avalanches will become likely on Thursday due to rainfall. Loose wet avalanches are likely to be small and confined to steeper slopes in all elevation bands in the Hurricane Ridge area. Be especially wary near terrain traps, where even a small avalanche could have unintended consequences. Larger and more dangerous avalanches are more likely outside the Hurricane Ridge area on the SW slopes of the Olympics due to heavier rain.

Snowpack Discussion

Deep storm snow that fell during mid-late December is well settled, homogeneous and has stabilized so the current avalanche danger should be confined to the uppermost recent storm snow.

The latest period of moderate snowfall should have deposited about 1.5 feet of snow at Hurricane from about Friday to Sunday with fluctuating snow levels and periods of strong, mostly S-SW winds.

A few additional inches of snow likely accumulated Monday through Wednesday, with the Waterhole NRCS slowly rising to 76 inches through mid-week.  

NWAC forecaster Garth Ferber is headed to Hurricane Ridge to attempt to fix the NWAC Hurricane Ridge station with the help of NPS IT staff. We wish them luck and hope that the winds on Thursday don't blow Garth back to Port Angeles before he fixes the station! 

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.

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.