Avalanche Forecast
Regions: Olympics.
Despite a favorable cooling trend Saturday, wind loading near and above treeline will maintain the possibility of human triggered avalanches specifically on lee slopes. A stronger storm with an uncertain track on Sunday should result in rising avalanche danger for the latter half of the weekend.
Detailed Forecast
With a favorable cooling trend Saturday and only light new loading expected the avalanche danger in the Hurricane Ridge area will focus on new wind slab found on lee northerly aspects mainly near and above treeline. Watch for firmer wind transported snow and be aware of local loading patterns in your terrain. Shallow storm slabs may build late Friday night through Saturday morning.  Â
Cornices should not be particularly sensitive on Saturday, but they are large so continue to give them a wide berth when travelling along ridgelines since they can break further back then expected.Â
The loose wet potential should be minimized by the cooling trend and cloudy skies. If the sun does break out Saturday, mid-March sunshine will rapidly increase the likelihood of loose wet avalanches on steeper solar aspects. Â
A cool yet powerful storm system on Sunday should lead to increasing avalanche danger. However, the storm track is uncertain and the avalanche danger will be reassessed with Saturday's forecast issuance.Â
Snowpack Discussion
Weather and Snowpack
The nonstop active weather pattern continues to push a storm system through the PNW almost every day or two with fluctuating but generally moderate snow levels. The last storm impacted the area Wednesday through Thursday with a warming trend that peaked Wednesday night with the frontal passage in the early morning hours and also featured very strong winds. Winds decreased Thursday afternoon along with decreasing shower activity. Generally 1.5 to 3 inches of water accumulated along the west slopes in the 36 hours ending 4 pm Thursday. Similar amounts were likely seen at Hurricane Ridge. The Waterhole NRCS snowdepth has stayed steady over the last few days due to the alternating periods of rain and snow.Â
The mid and lower snow pack in the Olympics should generally be a stable mix of crusts and layers of moist and rounded snow crystals.
Recent Observations
NWAC pro-observer Matt Schondwald toured around the Hurricane Ridge area Friday. He found up to 20 cm of dense, 1 finger or pencil thickness snow above the latest rain crust. The thin wind slab was generally unreactive except in isolated areas on N-NW lee aspects near treeline. Although cornices were large, they were generally firm and not sensitive. Matt observed evidence of a widespread natural cycle involving shallow slabs on northerly lee aspects that likely occurred during the Wednesday night warming trend and transition to rain. Windward slopes that had melted out a few weeks earlier had packed on a firm and in places icy thin cover. Overall, Matt noted few current avalanche problems in the Hurricane Ridge area Friday.  Â
Hurricane Weather Station
Internet communications to the station have been disrupted at the NWAC office. We have identified the problem but unfortunately our hardware will not be repaired until early next week. We apologize for the outage and are working to get the station back up ASAP.Â
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
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