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Archived

Avalanche Forecast

Feb 20th, 2017–Feb 21st, 2017
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Olympics.

Shallow storm slab should be less sensitive Tuesday but evaluate recent snow carefully before committing to steeper terrain.  

Detailed Forecast

Another low pressure system will track across Oregon Tuesday but this one is forecast to bring little snow to the Olympics. 

Shallow storm slab should be less sensitive Tuesday but evaluate recent snow carefully before committing to steeper terrain.  

Loose wet avalanches will not be indicated as an avalanche problem but watch for loose wet surface snow if you find yourself on solar slopes during sunbreaks.

Snowpack Discussion

Weather and Snowpack

Hopefully the last atmospheric river of the season arrived on Valentines Day 2/14 bringing another round of heavy rain, avalanches, crusts and consolidation through Thursday 2/16 in the Olympics. Minor snow was seen at Hurricane Ridge at the tail end of the storm.

A short period of fair weather on Friday 2/17 caused another surface crust. Light amounts of new snow accumulated over the weekend. The NPS rangers reported 5 inches of snow Monday morning at Hurricane Ridge. A slight warming trend was observed Monday along with generally light winds and light precipitation.   

Recent Observations

NWAC pro observer Matt Schonwald traveled to the Hurricane Hill region Friday. A hard, slick surface crust made travel precarious early Friday before the sun and warming began softening the crust. The few inches of snow fell during the tail end of the storm had bonded well and filled in many rain runnels, helping to smooth surface conditions. There was little evidence that the latest rain event produced any avalanches. The main hazard in the Hurricane area appeared to be an uncontrolled fall on the slick crust.

An observation via the NWAC Observations page for Hurricane reports a size-able loose wet avalanche on the W-SW side of Steeple Rock that probably occurred during the 2/14-2/16 period.

An observation via the NWAC Observations page from Mt. Ellinor on Sunday reported locally more snowfall and touchy avalanche conditions on Sunday.  

Avalanche Problems

Storm Slabs

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: Possible

Expected Size: 1 - 1