Avalanche Forecast

On Tuesday, a frontal system will bring a cool down with new snowfall accumulating above 4500-5000 ft by the afternoon. You may still trigger Loose Wet avalanches or they may be triggered by additional rainfall Tuesday morning. Watch for signs of wet snow conditions such as sluffing, roller-balling and any natural Loose Wet avalanches as signs of an increasing hazard. Loose Wet avalanches still have the ability to become large in isolated areas that received more snowfall over the weekend and where they gouge down to deeper layers of moist or wet snow. 

Shallow new Wind Slabs may form on lee slopes near and above treeline by the afternoon. Use visual clues such as fresh cornices, wind drifted pillows and cracks in the snow all indicating that you could trigger a Wind Slab avalanche. 

Large fresh cornices will still be fragile due to recent warm temperatures and initial rainfall Tuesday morning. Give cornices a large margin of safety and avoid travel on slopes below, as cornice failures may trigger large avalanches on slopes below.

Monday was warm with filtered sunshine. The dry weather followed the strong weekend storm which initially pushed rain into the near elevations band early Saturday. Cooling and new storm snow followed through Sunday afternoon. There was a significant snowfall gradient with elevation with this spring storm. Wet snow avalanches likely occurred earlier in the storm and continued at lower elevations through the weekend. New Wind and Storm Slabs likely developed at higher elevations later in the weekend with fresh cornices developing along ridgelines.   

Older layers of weak snow can be found in the snowpack. We have limited information about the distribution and reactivity of these layers leading to a higher level of uncertainty. If you have any information or observations on layers within the snowpack please consider submitting them to NWAC via our public observations page. The exact weak layer and depth depends on your location. Common weak layers found over the last month: 

• 3/25 and 3/22: Buried surface hoar layers found on shaded aspects near and above treeline.
• 2/13 Facets above a firm and thick melt-freeze crust can be found in many locations near and above treeline. This layer is thought to be dormant at this time but may re-awaken with a substantial weather input.

Rainfall and continued above freezing temperatures Friday night and Saturday morning may have allowed Wet Slabs to fail at these interfaces. Persistent Slabs may be reintroduced when we receive more snowpack information. 

Lower elevations further east of the crest have melted back for the season and no longer present an avalanche risk. 

Observations

North

No recent observations. 

Central

On Friday 4/6, professional observer Matt Primomo traveled up the Icicle to above Colchuck Lake. Matt found a moist and well settled snowpack below 5800' with no persistent weak layers. The 2/8 crust was 1 m down.  At 6700' on a NNE aspect, Matt found preserved stellars 14 in (35 cm) down and showing a likelihood to propagate in snowpack tests. Dry snow was found at this elevation below the top 8 " (20 cm). Higher in the terrain, recent wind slab avalanches likely released on this layer. Matt also observed natural loose wet avalanches and one wet slab avalanche above treeline on a SE aspect.  

On Saturday 3/31, an observer reported a large slab avalanche that likely failed on a persistent weak layer 4-5 feet below the surface in the Enchantment Mountians

On Friday 3/30, Matt Primomo was on Dirtyface Mountain where he found two buried surface hoar layers (3/22) on shaded aspects at variable depths within the two feet of the snowpack. Test results indicated the potential for propagation on both weak layers. Snow pits indicated a weakening 2/8 crust.