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 24th, 2014–Mar 25th, 2014

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

Olympics.

The avalanche danger should mainly shift to new snow layers by the end of the daylight hours on Tuesday.

Detailed Forecast

A weakening cold front will cross the Northwest on Tuesday morning. This should cause light rain or snow with cooling temperatures.

Then a stronger short wave should cross the Northwest Tuesday afternoon and night. This should cause increasing rain or snow beginning in the Olympics Tuesday midday.

The rain mainly Tuesday afternoon should help small wet loose avalanches remain possible mainly near and below treeline on Tuesday. Watch for wet surface snow deeper than a few inches, pinwheeling of surface snow and small natural wet loose releases that usually precede more major wet loose snow avalanches.

New small wind slab should become likely starting Tuesday afternoon mainly above treeline on lee slopes. Watch for signs of cracking or firmer wind transported snow.

New small areas of storm slab should also become likely starting Tuesday afternoon also mainly above treeline on sheltered slopes. This is most likely in any areas that receive heavier snowfall.

In many areas the cooling trend may also bond new snow to old snow and build favorable stable new snow profiles.

Snowpack Discussion

A wet cold front 15-17 March stalled over the Olympics and the north Cascades and then produced mainly rain before changing to snow in a north to south fashion across the area. A favorable temperature trend with a gradual cooling occurred with this storm. The NWAC site at Hurricane picked up about 13 inches of snow late Saturday through Monday. This weather produced wind slab layers on north through east aspects near tree line and allowed for one skier triggered soft slab Sunday afternoon that covered the road. 

Another cold front crossed the Northwest on Wednesday. This system produced more snow in the Cascades with the Hurricane Ridge weather station recording only about 4 inches of new snow at low temperatures and with generally light winds. On Friday afternoon NWAC observer Katy Reid denser wind slab on N thru SE near treeline that was stubborn in stability tests and did not note in any recent avalanches.  She also observed widespread surface hoar from Thursday night along with graupel as being preserved under cool temperatures and light winds but this was reported as destroyed by the end of the weekend.

On Sunday Katy reported numerous small to large wet loose avalanches on solar aspects but dry loose avalanches on due north aspects at higher elevations.  She also found wind slab in the limited above treeline zone near Hurricane Ridge to be prone to snowpit test failures down 20 cm at a melt freeze crust on the colder N-NE aspects.

Wet loose conditions are expected to be continuing on this warm Monday on solar slopes. 

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). 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.