Avalanche Forecast

Cooler temperatures, cloudy and showery weather is expected Monday.  This weather should maintain areas of wet and weak snow below about 4-5000 feet in the Below Treeline elevation band. Moderate to strong winds at the higher elevations may build new shallow wind slabs on some leeward exposed ridges, mainly NW-E facing.  Firm wind transported snow and snowpack cracking can be good signs of wind slab layers.

Recently formed cornices have grown large and can become sensitive during mild weather, especially following nights with above freezing temperatures.  Avoid areas on ridges or summits where there may be a cornice and avoid slopes below cornices in the spring. Cooler temperatures Monday may help temporarily strengthen cornices Monday.

Due to recent sensitive storm slab releases on suspected buried surface hoar layer, March 12th, we are now listing this layer, though it may be spotty and not widespread, it should nonetheless draw attention from travelers in the NE zone. 

Weather and Snowpack

A combination of sun and cloud with mild temperatures for several days gave way to mild temperatures and spotty light rain Sunday, March 20th. The recent weather over the past five days has allowed for the 2 to 3 feet of storm snow that accumulated from about March 9-15 to settle and mostly stabilize. Wind, sun, warmth, freezing and some light rain have changed snow conditions over the past five days. Surface snow conditions have become more variable, ranging from still good settled cold snow on steep shaded slopes and a mix of surface crusts, wind buffed surfaces or shallow moist to wet snow on other aspects.

Earlier avalanche problems of wind and storm slab have been settling and stabilizing in most locales, but more triggered wind and storm slabs continue to be reported in the NE Washington Cascades as of Friday and Saturday. Most east slope sites have seen the snowpack settle 6-12 inches over the past five days, since the strong storms ended March 15th. 

The recent storms have also built large cornices along ridges in many areas with several large cornice releases noted over the last few days.

A spotty layer of surface hoar likely formed and was buried by 3/12 in some areas, with the terrain most suspected N-E facing slopes in the upper elevations of the below treeline and near treeline band.  

No avalanches have been noted for quite some time on a persistent buried surface hoar layer from February 27th in the Washington Pass area and to a lesser extent the central-east zone. Avalanches on this layer are now unlikely.   

We are no longer tracking any layers of concern formed earlier this winter in the mid or lower snowpack due to lack of recent activity at these interfaces and confirming field observations. 

Recent Observations

NWAC pro-observer Tom Curtis tested conditions along the Nason Ridge area to Rainy Pass Saturday, March 19th. No significant layers were found in test pits or on slopes. In general, shallow wet snow was found below treeline with shallow stubborn wind slabs on some isolated features near ridges that were gaining strength. 

Recent reports from the Washington Pass area Friday and again Saturday, March 18-19, indicated some shallow wind slabs were remained sensitive to human trigger as well as some shallow storm slabs in lower elevations, possibly on the 3/12 persistent layer. 

At least 2 recent cornice releases in the Washington Pass area caused large size 3 storm slab and car sized blocks running to the valley floor.

Tom Curtis was on Mt Cashmere Thursday 3/17 and found about 35 cm of storm snow well bonded to an underlying crust from last week. An extended column test did not indicate propagation and only small loose wet avalanches were seen on steep solar slopes. Temperatures did not greatly affect the snowpack.

The Mission Ridge pro-patrol reported limited wind transport on Friday, 3/18 from east winds and surface crusts below about 6000 feet from sun and warmth.