Avalanche Forecast
Regions: Olympics.
Persistent westerly winds will load lee slopes near and above treeline such that wind slab will be the primarily hazard on Thursday. By avoiding obviously wind loaded slopes, you can enjoy some fine late season conditions. Loose snow and storm slabs avalanches should be lesser concerns on Thursday.
Detailed Forecast
Cool NW flow should deliver a taste of winter in late March with light to moderate orographic snow showers along the Olympics Thursday. From late Wednesday night through Thursday, new snow should layer right side up as temperatures cool behind the cold front Wednesday night. Deep post-frontal moisture should prevent widespread solar affects, but some daytime warming is likely Thursday afternoon despite the seasonally cool air mass overhead.Â
Persistent westerly winds will load lee slopes near and above treeline. Wind slab will be the primarily hazard on Thursday. By avoiding obviously wind loaded slopes, you can enjoy some fine late season conditions. Firm wind transported snow and snowpack cracking can be good signs of wind slab layers.
Loose dry avalanches should be small but likely on steeper non-solar slopes. Be aware of terrain traps where even a small loose avalanche could have unintended consequences in the wrong terrain. Loose wet avalanches will not be listed as the primary loose snow avalanche problem, but loose wet avalanches will be possible on steeper solar slopes especially if the sun pokes out briefly.  Â
Storm slabs should be a lower concern Thursday. Storm slabs will be more likely in areas that see subtle warming Thursday. During more intense showers Thursday, watch for graupel layers that can become bed surfaces for storm slabs.Â
Recently formed cornices have grown large. If traveling along ridgelines, be aware that cornices break much further back than expected and you don't want to go for a ride with a chunk of cornice. Despite the cool weather, cornice releases can be unpredictable during the spring.
Snowpack Discussion
Weather and Snowpack
About 2-3Â feet of snowfall accumulated at Hurricane March 9-15th.
A combination of sun, mild temperatures and then some rain was seen for several days ending about Sunday 3/20. This weather caused about 10 inches of consolidation of the recent snow at Hurricane which is usually a sign of a strengthening snowpack.
Older winter avalanche problems of wind and storm slab in the Olympics will have mostly settled and stabilized during the mild weather.
Frequent March storms have built large cornices along ridges in many areas.
A low pressure system crossed the Northwest on Monday and Tuesday. Up to a few inches of new snow is likely at Hurricane.
The mid and lower snowpack in the Olympics should generally be a stable mix of crusts and layers of moist and rounded snow crystals.
Recent Observations
A Park ranger at Hurricane found variable surface crusts Saturday morning 3/19, as overnight temperatures remained well over freezing.
A couple reports on Turns All Year for the Olympics for Friday and Saturday 3/18-19 for Mt Angeles and the Seven Lakes Basin indicated big pinwheels on solar slopes, a sign of loose wet snow conditions, and cold snow lingering on non-solar slopes.
Hurricane Weather Station
Internet communications were restored to the station on 3/23! Â Thank you for your patience.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, South East.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Loose Dry
Release of dry unconsolidated snow. These avalanches typically occur within layers of soft snow near the surface of the snowpack. Loose Dry avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs. Loose Dry avalanches can trigger slab avalanches that break into deeper snow layers.
Loose Dry avalanches are usually relatively harmless to people. They can be hazardous if you are caught and carried into or over a terrain trap (e.g. gully, rocks, dense timber, cliff, crevasse) or down a long slope. Avoid traveling in or above terrain traps when Loose Dry avalanches are likely.
Loose Dry avalanche with the characteristic point initiation and fan shape.
Loose dry avalanches exist throughout the terrain, release at or below the trigger point, and can run in densely-treed areas. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
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