Regions
Northwest Inland.
Rising freezing levels, light rain, and the sun's influence are the main concerns for the next few days. Watch for moist or wet snow. Recent wind slabs may also become more sensitive to triggering with the warming trend.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
TONIGHT: Mostly cloudy. Ridge wind moderate, south. Alpine temperature near 0. Freezing level 1600 m.TUESDAY: Cloudy, wet flurries. Accumulation 5-10 cm. Ridge wind strong to extreme southeast. Alpine temperature near 0. Freezing level 1600 m.WEDNESDAY: Mix of sun and cloud. Ridge wind moderate to strong, southeast. Alpine temperature near 0. Freezing level 1500 m. Snow beginning in the evening.THURSDAY: Mix of sun and cloud, snow ending. Accumulation 5-10 cm. Ridge wind light, southwest. Alpine temperature near -2. Freezing level 1200 m.
Avalanche Summary
On Sunday there was a report from the Howson range of a natural, size 2 wind slab release on a wind-loaded, northeast aspect at 2050 m, as well as evidence of previous widespread smaller activity as a result of wind loading.Last week, on Thursday a widespread natural avalanche cycle (up to size 2), triggered by intense wind loading was reported from the northern part of region.While on Wednesday, a natural size 3.5 avalanche that initiated as a storm slab then stepped down to a deeper weak layer, and a solar triggered size 2 avalanche were reported from the Howson range. Skier triggered size 1 storm slab releases on a buried sun crust (30 cm deep) on a southeast aspect at 1700 m were also reported in the same area.
Snowpack Summary
Rising freezing levels and daytime warming have created moist or wet snow surfaces on all but alpine, northerly aspects where 20 cm up to 50 cm of recent storm snow has been redistributed by strong winds. Weak layers buried around March 19th are roughly 40 cm below the surface (up to 100 cm in deeper snowpack areas). These weak layers include surface hoar on shaded aspects at high elevations and hard crust layers on solar aspects and below treeline.Near the bottom of the snowpack, weak and sugary facets are found in shallow, rocky snowpack areas. Storm slabs have stepped down to these facets and producing very large avalanches in northern parts of the region.
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.