Avalanche Forecast

Light to moderate west winds and a couple inches of new snow should be seen in the near and above treeline zone along the east slopes Monday night and Tuesday. Temperatures should continue to slightly cool from the previous couple days.

This weather may build new, isolated shallow wind slab on lee slopes in the near and above treeline through the day light hours on Tuesday. This is most likely on N-SE slopes. Firm wind transported snow and snowpack cracking can be good signs of wind slab layers.

Continued wet snow conditions can't be ruled out on Tuesday. The cooler temperatures should limit this problem to the below treeline. Watch for wet snow deeper than a few inches and pinwheels or natural releases.

Recently formed cornices have grown large and can become sensitive following nights with above freezing temperatures.  Avoid areas on ridges or summits where there may be a cornice and avoid slopes below cornices. Cooler temperatures Tuesday may help to temporarily strengthen cornices Tuesday.

Due to recent sensitive storm slab releases on the suspected spotty 3/12 buried surface hoar layer, we are currently listing it as a persistent slab. Though it may be spotty and not widespread it should nonetheless get attention from backcountry 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 along the east slopes from about March 9-15 to settle and mostly stabilize. Recent 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 areas but more triggered wind and storm slabs were reported in the northeast Cascades 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.

Little if any new snow reached the east slopes on Sunday night.

Recent storms did build large cornices along ridges in many areas with some recent natural releases noted.

A spotty layer of surface hoar likely formed and was buried on about 3/12 mainly the northeast Cascades with the terrain most suspected being N-E facing slopes.

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 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

The North Cascades Heli Skiing operation skied extensively on a non-solar slope in Cedar Creek on Monday 3/21 with no avalanches.

The North Cascade Mountain Guides at Washington Pass area Friday to Sunday 3/18-20 reported no results from ski cuts and no signs of instability. On Friday a loose wet avalanche that triggered a small 40 cm deep slab. Cornices in this area area sagging greatly and snow in the below treeline was moist and heavy in the afternoons. 

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. 

Reports via guides and a private email to the NWAC indicate 2 recent cornice releases in the Washington Pass area with a large size 3 storm slab and car sized blocks running to the valley floor.