Avalanche Forecast
Regions: Olympics.
A further gradual decrease is expected in the avalanche danger Wednesday. Continue to watch for firmer wind transported snow and previous wind slabs on exposed lee slopes especially near and above treeline.
Detailed Forecast
Cloudier weather should be seen Wednesday with light winds and little change in cool temperatures. A few light showers are possible but most parts of the Olympics and Cascades should just end up with clouds.
These conditions should allow for further gradual decrease in avalanche danger as recent wind and storm slabs further settle and further stabilize.Â
Recently formed wind slab should further stabilize on Wednesday.  Wind slabs are most likely on SW-NW-NE aspects due to recent strong E-SE transport winds. Watch for recent wind effects near and below ridgelines and avoid steep slopes with obvious signs of recent wind loading.
Storm slabs should become more unlikely and more stubborn to trigger Wednesday and will be removed as an avalanche problem.
It should be cloudier on Wednesday than the past couple days and further loose wet avalanches seem unlikely. Loose wet avalanches will not be listed as an avalanche problem. Watch for loose wet snow conditions on steep solar slopes if there is unexpected significant sunshine on Wednesday afternoon.
Snowpack Discussion
Weather and Snowpack
An arctic air mass was over the Northwest with fair, cold weather the 2nd week of January. Surface hoar and near surface faceted crystals formed in wind and sun-sheltered areas during this period. But recent observations in the Olympics seem to indicate that these crystals did not survive the atmospheric river that began on 1/17.
An atmospheric river moved over the Northwest about 1/17. Heavy rain was seen up to about 5500 feet in the Hurricane Ridge area. Three day precipitation totals through about Thursday were about 2.5 inches at Hurricane Ridge. An avalanche cycle likely occurred in the Olympics during this period.
The NPS rangers reported a storm total of 15 inches of lower density snow at the Hurricane Ridge manual snow plot Thursday morning. Showers continued during the day Thursday, but our precipitation gage didn't record any precipitation after 9 am, possibly due to equipment problems. About a foot of snow fell at the Waterhole NRCS Snotel over a 24 hour period ending Friday morning.Â
A very pleasant day Saturday allowed temperatures at Hurricane to reach the freezing mark. Showers late Saturday and another band Sunday deposited about 4-6 inches of new snow as of Sunday afternoon at Hurricane, with strong S-SE winds.
Fair weather with light winds and cool temperatures has been seen Monday and Tuesday.
Recent Observations
On Wednesday 1/18 NPS personnel reported debris in the Old Faithful track down to the Hurricane Ridge road at 3500 feet. Debris piled up 10-15 feet deep in this narrow slide path.
NWAC pro-observer Matt Schonwald, was at Hurricane Ridge Friday. Matt found 10 inches of settled recent storm snow generally well bonded to the underlying rain crust and not reactive. SE winds were forming shallow wind slabs on lee slopes near treeline. The recent rainfall had penetrated well into the snowpack. At a limited number of test sites, the 12/17 PWL was found to be rounding and unreactive in snowpit test and well over a meter down. We feel comfortable removing the persistent slab from the avalanche problem list moving forward.
A report from Klahane Ridge via the NWAC Observations page on Sunday indicated wind loading to N slopes at 6000 feet. Rain had penetrated to 1 m in the snowpack and the 12/17 layer was bonded and difficult to identify.
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, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1