Avalanche Forecast

A warm front is moving over the Northwest on Tuesday. A second frontal system will move over the Northwest Tuesday night and Wednesday. The second system will cause periods of moderate to heavy rain or snow with further gradually rising snow levels Tuesday night and Wednesday.

An avalanche cycle is expected by Tuesday night and should last into Wednesday. Snow that has accumulated since the mid-March avalanche cycle may be involved or entrained in avalanches.

SW alpine winds are likely to begin to build new wind slab on mainly N-SE slopes on Tuesday night and Wednesday. Alpine winds have been predominately from the SW-WSW the pasts few days with some SE winds seen at the top of Crystal. Hence NW to SE slopes will be indicated.

Loose wet avalanches will be likely in the near treeline and below treeline where there is significant rain and warming.

Recent cornices are very large. Natural cornice releases and resulting slab avalanches are unpredictable. See a blog post regarding cornices here.

Although they won't be listed as avalanche problems, new storm slab is very likely at higher elevations and wet slab avalanches are possible at lower elevations.

Very dangerous avalanche conditions are expected on Wednesday and travel in avalanche terrain is not recommended in this area.

Special Note: For more information on the massive natural cornice triggered avalanche on the north side of Ruby Mountain on Sunday 3/19 and general thoughts about low-likelihood/high consequence avalanches, please see NWAC's blog post issued, Sunday, March 26. 

Weather and Snowpack

The first week or so of March was very cool and snowy. NWAC stations along the west slopes of the Cascades piled up about 3 to 8 ft of snow with the most at Mt Baker.

The 2nd week of March was equally active with non-stop Pacific frontal systems pummeling the PNW. Unfortunately, these systems delivered far more rain than snow. At least two regional avalanche cycles occurred during the stretch. Significant snowpack consolidation occurred over this period due to rainfall and warmer temperatures. 

A strong low pressure system brought several inches of rain to the west slopes of the Cascades outside the Cascade Passes on Friday, 3/17 and caused another wet snow avalanche cycle in the Mt. Baker area Friday night into early Saturday morning. 

This past week has also been active weather-wise, but water amounts/snowfall totals have been slightly lower relative to the extreme wetness of the past few weeks. In the last 5 days ending Monday morning NWAC stations near and west of the Cascade crest have picked up 1.5-4 ft of snow with the most at Mt. Baker and above the Pass levels.

Recent Observations

North

The Mt Baker patrol reported heavy snow and increasing 6-14 in storm slab from explosive avalanche control on Tuesday morning.

Central

NWAC Observer Matt Schonwald was in the Alpental Valley Saturday and identified about 14-18 inches of storm snow over the past few days had a favorable density profile. There was evidence of shallow storm slabs being triggered earlier in the day, but gained significant strength through the day. On solar aspects daytime warming caused shallow, loose-wet slides, mostly D1, up to D1.5.  

South

On Friday, as the snow-line crept up during the day natural loose wet avalanches occurred along the Paradise Road above 5000'.  NPS rangers estimated the loose wet slides entraining about 8-10" of the recent storm snow. 

NWAC Observer Jeremy Allyn was in the Crystal BC Saturday, in Lakes Basin and near Norse Peak. Recent storm snow varied widely based upon elevation and aspect with up to 20 inches of storm snow or more near and above treeline on non-solar terrain, over the hard rain crust from last weekend. Many steep north aspects within the terrain had been skied both earlier and on Saturday with no triggered avalanches noted. Test profiles and snowpack tests at 6400 feet on a NW aspect below ridgeline, identified weak faceted snow,both above and below the rain crust buried about 20 inches in that location.