Avalanche Forecast

A bit of a break in the weather should be seen Tuesday night and Wednesday morning. Southwest flow should begin to carry another front to the Northwest beginning in the Olympics and northwest Cascades Wednesday afternoon and to the rest of the Cascades Wednesday night. Significant new snow layers are generally not expected in the Cascades through most of the daylight hours on Wednesday. Remember that you may need to adjust your plans if the next front arrives with wind and rain or snow sooner than expected.

Continued loose wet snow conditions can't be ruled out on Wednesday especially if there are sun or solar effects. Surface crusts in the morning  don't mean that loose wet snow conditions won't develop by the afternoon. This is mostly likely on solar slopes but can't be ruled out on other aspects. Watch for wet snow deeper than a few inches and pinwheels or natural releases.

Recently formed cornices have grown large and with another release reported at Mt Hood on Tuesday. Avoid areas on ridges or summits where a cornice may be present and avoid slopes below cornices. Cornice releases can be unpredictable during the spring.

Small areas of previous wind slab may remain present on lee slopes. This should be mainly northwest to southeast aspects near ridges and summits. Firm wind transported snow and snowpack cracking can be good signs of wind slab layers.

Due to recent sensitive storm slab releases on a 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

About 2-3 feet of snowfall accumulated along the east slopes March 9-15th.

A combination of sun, mild temperatures and then some rain was seen for several days ending about Sunday 3/20. This weather caused about 6-12 inches of consolidation of the recent snow along the east slopes. Surface snow conditions became highly variable, ranging from cold snow or wind buffed surfaces on non-solar slopes to morning crusts and wet snow on solar slopes.

Recent storms did build large cornices along ridges in many areas.

A low pressure system crossed the Northwest on Monday and Tuesday. NWAC stations along the east slopes had about 0-4 inches of new snowfall ending on Tuesday morning.

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 also 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.