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

Feb 20th, 2016–Feb 21st, 2016

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

Regions

Olympics.

Watch for new building wind or storm slab layers beginning Sunday morning in the Olympics.

Detailed Forecast

A moderate front should cause increasing winds and spread increasing snow especially to the near and above treeline in the Olympics Sunday morning with a slight warming trend.

This weather should build new wind slabs on lee slopes mainly near and above treeline. Watch for new or previous firmer wind transported snow mainly on the lee N to SE slopes below ridges.

New storm slab is likely where more than several inches of snow rapidly accumulates Sunday.

A slight warming trend should help to enhance new wind and storm slab layers on Sunday.

Snowpack Discussion

Weather and Snowpack

Rain and mild temperatures dominated last Sunday and Monday forming the latest crust in the Olympics. There was about 1. 5 inches of rain at Hurricane over the 2 days ending Tuesday morning.

An active and at times stormy, cooler pattern began to bury the crust on February 17th and brought about 10 inches of snow to Hurricane Wednesday to today.

The mid and lower snow pack in the Olympics should be a stable mix of crusts and layers of wet rounded snow crystals.

 Recent Observations

Professional NWAC observer, Matt Schonwald was at Hurricane Ridge on Friday. Recent storm snow deposits of about 4-6 inches had accumulated in wind sheltered locations. Very strong southerly winds were building shallow wind slabs on lee slopes near tree line below ridges and also building small cornices. Matt recommended giving new wind slab a wide berth.

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.

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.