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Archived

Avalanche Forecast

Jan 23rd, 2016–Jan 24th, 2016
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
1: Low
The avalanche danger rating below treeline will be low

Regions: Olympics.

Watch for recent shallow wind slabs that may have formed on the lee, northerly aspects below ridges, mainly near and above treeline.

Detailed Forecast

Partly to mostly cloudy Sunday, cool with light winds. This should allow for a slow decrease in danger. The main concern are areas of shallow wind slabs on lee slopes near ridges. Any previously wet or moist surface snow should have formed a strengthening crust by Sunday, locally decreasing danger. Further continued snowpack settlement should also allow for an improving trend.

Watch for recent shallow wind slabs that may have formed on lee, northerly aspects below ridges.

Snowpack Discussion

Moderate rain fell to high elevations Wednesday night and Thursday, before gradually cooling and depositing about 4 inches of snow by Friday. The gradual cooling formed good bonding to the forming crust as observed by NWAC observer Matt Schonwald Friday. The rain event caused a loose wet avalanche cycle on steeper slopes in all elevation bands

Matt reported generally stable surface snow conditions with no layers of concern in the BTL and NTL elevation zones. Overall the snowpack consists of a few inches of saturated snow, well bonded to supportive dryer, old snow and a newly forming crust. Stability tests were all negative. Some transport of loose surface snow was seen being deposited on the northerly facing terrain below ridges, but no distinctive wind slab had formed as of Friday afternoon. 

Hurricane Ridge weather station update: NWAC forecaster Garth Ferber was at Hurricane Ridge Thursday and with the help of NPS IT staff, our weather station is back online!  We appreciate everyone's patience and believe that our new internet connection to the weather station will prove to be far more reliable than the aging microwave it replaced last spring. 

Avalanche Problems

Wind Slabs

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.

 

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

 

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

 

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

Aspects: North, North East, East, North West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 1