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

Mar 26th, 2014–Mar 27th, 2014

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

Stevens Pass.

Recent snow from Tuesday through Wednesday will remain susceptible to solar effects Thursday. Remember to evaluate snow and terrain carefully on Thursday.  Watch for signs of wind transported snow near or especially above treeline.

Detailed Forecast

An upper trough passage Wednesday night should continue to cause showers with additional light amounts of new snow expected. Further but mostly light snow showers are expected Thursday as weak high pressure rebuilds to the west. 

The main concern should remain the possibility of loose wet snow avalanches. The recent 4-12 inches or greater of snow should be susceptible to the destabilizing effects of rapid warming due to solar input during extended sun breaks or clearing periods between showers.

Remember to evaluate snow and terrain carefully on Thursday. Watch for wet surface snow deeper than a few inches, roller balls in surface snow and small natural wet loose releases that usually precede more major wet loose snow avalanches.

New or recent small areas of wind slab should also be possible Thursday mainly above treeline on lee slopes. Watch for signs of cracking or firmer wind transported snow.

Snowpack Discussion

We have shifted avalanche concerns to more recent layers and moved away from deeper snowpack concerns from earlier this winter.

A cold front crossed the Northwest a week ago with snowfall at NWAC sites near and west of the crest ranging from 3 to 19 inches with a cooling trend. On Thursday a skier at Stevens Pass in a NNW facing chute at 5400 feet called Fleur de Lis triggered a 6-8" storm slab, lost some gear but fortunately was uninjured. You can read a first hand candid and honest description posted on Turns-all-year. 

Several other natural and triggered storm slab avalanches were reported. NWAC observer Jeff Ward was at Jim Hill near Stevens Pass on Friday - here is a video.

Increasingly warmer weather occurred Saturday through Monday, with Monday being the warmest of the days.  Reports indicated some powder surviving on north slopes and wet loose avalanches on solar slopes. NWAC observer Dallas Glass at Paradise Saturday and a report on Turns All Year from Crystal Saturday indicated small to large triggered wet loose snow avalanches.  More sobering, however was the fatal avalanche accident Saturday on Granite Mountain near Snoqualmie Pass - see initial reporting below.

While touring east of Steven Pass near Lichtenberg Mountain today, Wednesday the 26th, NWAC observer Dallas Glass came upon several wet slab avalanches that released along the southwest flank.  One slide was rather massive, at least a D3 on the destructive scale with an estimated crown ranging from 2-3 meters! Large timber was taken out with a debris field over 30 ft high and covering the size of about two football fields. There were some recent ski tracks that were covered by the debris so based upon that and recent weather, it most likely released Monday which was the warmest day, following another warm day Sunday.  The photos below give some indication, but look for a new video from Dallas soon.

Very large wet slab release along SW flank of Lichtenberg, east of Stevens Pass, likely released Monday, March 23. See crown near upper right! Photo: Dallas Glass 

Granite Mountain Accident: Around 4:45 PM on Saturday afternoon 2 skiers and a dog began descending the skier's right avalanche path on the south side of Granite Mountain. They triggered a slab avalanche that stepped down to a deeper slab. Upon review of crown photos and conversations with avalanche professionals from Snoqualmie Pass it seems that the initial slab failure on this cross loaded path included the Wednesday storm snow. The deeper second slab of similar depth included 16-17 March storm snow with the bonds between these layers weakened by strong solar input and potential melt water in the upper snowpack during the afternoon. The best estimate right now is that both slabs were at least 1 foot in depth.

The skier caught and killed in the avalanche skied off the ridge at about 5200 feet and onto a steep (40+ degrees) slope. The avalanche became a large and destructive funneling down to around 2300', entraining wet snow lower in the avalanche path and at times gouging to the ground. Size estimates are at least D3/R3. The other skier was in a safe zone and not affected. The skier that was caught was buried under 20 feet of debris, but was recovered Sunday morning by local search and rescue personnel.

Photo of Granite Mountain avalanche taken 23 March 2014 by Jason Skipper.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.