menu
print

Snoqualmie Pass

Issued: 6:10 PM PST Friday, January 19, 2018
by Kenny Kramer

NWAC avalanche forecasts apply to backcountry avalanche terrain in the Olympics, Washington Cascades and Mt Hood area. These forecasts do not apply to developed ski areas, avalanche terrain affecting highways and higher terrain on the volcanic peaks above the Cascade crest level. 

Deep areas of wind and storm slabs should make triggering an avalanche in steep terrain possible or even likely. Avoid travel on steep slopes receiving wind deposited snow, where fresh wind slab deposits will be sensitive to human triggering. Expect dangerous avalanche conditions at higher elevations.  Choose conservative terrain, by travelling in wind sheltered terrain well away from avalanche paths.

Danger Scalei
  • No Rating
  • Low
  • Moderate
  • Considerable
  • High
  • Extreme

Avalanche Problems for Saturday

Wind Slabi

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.

  • Avalanche Problemi
  • Aspect/Elevationi
  • Likelihoodi
  • Sizei

Storm Slabsi

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.

  • Avalanche Problemi
  • Aspect/Elevationi
  • Likelihoodi
  • Sizei

Avalanche Summary:

In the passes, new storm snow amounts vary according to elevation as rain gradually changed to snow Wednesday night. By Friday, storm snow ranges from about 6-8 inches in lower terrain and 16-24 inches in higher elevation terrain. 

Above treeline, greater new snow amounts and periods of very strong winds have caused dangerous avalanche conditions. New wind and storm slabs in higher exposed terrain will require careful terrain choices and conservative decision making.  

Near and below treeline the precipitation began as rain and transitioned to snow. This has caused less dangerous conditions with new snow forming good bonding to the old rain soaked snowpack. However, heavy snowfall and moderate to strong winds have built increasing wind and storm slabs at progressively lower elevations. There are still heightened avalanche conditions with new and increasingly deep wind and storm slabs of 1-2 ft or more as of Friday.

The old rain wet snow continues to gradually re-freeze and form a new crust layer.

The older snowpack has undergone several rain or warm periods and remains void of any significant layers of concern.

Observations

North

On Friday, professionals for NWAC traveled to near treeline and avoided higher exposed terrain above treeline due to potential for large and dangerous wind slabs. Takeaway was the active wind transport and new snow happening throughout the day as well as evidence of significant recent wind re-distribution of the deep storm snow. Most slabs encountered were shallow, soft slabs formed from wind loading. There was evidence of a large wind slab release above treeline on a north aspect with a depth roughly estimated at 3 ft or more.   Up to treeline there was about 2-3 ft of storm snow over the forming Jan 16 rain crust.

Thursday morning, the Mt Baker Pro Patrol reported fresh wind slabs were sensitive to ski cuts and were releasing in the 4-5 inch range, near treeline. Winds were reportedly very strong along ridges and actively transporting the new snow. 

Thursday morning, the Mt Baker Pro Patrol reported fresh wind slabs were sensitive to ski cuts and were releasing in the 4-5 inch range, near treeline. Winds were reportedly very strong along ridges and actively transporting the new snow. 

Central

NWAC staff traveled in the Alpental Valley Friday finding highly variable storm snow conditions due to the active and ongoing wind transport of the recent storm snow. Some exposed slopes were striped of new snow to firm crust layers with nearby slopes holding over 2 ft of wind deposited snow. Bonding to old wet snow was good. The forming rain crust was ski supportable above 5000 ft but remained soft and breakable below 5000 feet. 

NWAC forecaster, Dallas Glass was on Skyline Ridge at Stevens Pass Thursday and reported new storm snow of 8 inches at 4000 feet and 14 inches above 5000 feet. The bonding was good to the old rain wet snow. The crust had yet to re-freeze but was in the process. There was evidence of recent wind transport with a fresh natural avalanche having released on a steep east face about 5300 feet, likely during a brief warm up Wednesday night. There were storm slab layers noted from fluctuating temperatures overnight, but were not sensitive to human trigger in that location. 

South

On Friday, NWAC forecaster Dallas Glass traveled in the Crystal Mountain back country from 4200-6600 ft covering all aspects. The recent winds have caused highly variable storm snow conditions with exposed areas striped of recent snow and more wind loaded N-NE aspects holding up to 6 ft of storm snow! There was a lack of storm slab in wind sheltered terrain with widely varied wind deposited snow near treeline exposed to recent strong winds. 

Forecast for Saturday:

A band of enhanced snow showers should arrive Friday night with diminishing showers Saturday. This should freshen storm snow with winds continuing to redistribute new cold snow to lee slopes by Saturday. 

This weather should cause widely variable snow conditions with some wind exposed slopes scoured to recent crusts and lee slopes building deeper wind drifts and slabs. Watch for changes in snow conditions, particularly stiffer more dense snow, likely a wind or storm slab. Avoid travel on slopes if you encounter wind stiffened surface snow, especially on steeper exposed terrain and steep roll-overs.  

The temperatures should remain cool, depositing new low density snow that will be easy for winds to re-distribute on exposed terrain.  

Wind slabs near and above treeline remain the primary avalanche problem in this area, so remain conservative in your terrain choices especially as you venture into exposed terrain.

The best and safest snow will remain in sheltered terrain away from ridges. 

No Corresponding Mountain Weather Forecast Available

USE AT YOUR OWN RISK

This Backcountry Avalanche Forecast is provided in conjunction with the US Forest Service, and is intended for personal and recreational purposes only. Safe backcountry travel requires preparation and planning, and this information may be used for planning purposes but does not provide all the information necessary for backcountry travel. Advanced avalanche education is strongly encouraged.

The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and the accuracy or reliability of the data provided here is not guaranteed in any way. This forecast describes general avalanche conditions and local variations will always occur. This forecast expires 24 hours after the posted time unless noted otherwise.