Avalanche Forecast

Cool with light snow showers at times. Light snow accumulations expected with moderate ridge top winds, mostly from the NW. This should not significantly change the current danger and expect mostly shallow and stable snow conditions. 

If in areas receiving greater new snow, watch for wind transport building shallow wind slabs near ridges.

Shallow early season snowpack, especially lower elevations, has exposed terrain hazards. Expect terrain hazards with poorly covered rocks, vegetation and creeks, particularly on south-facing terrain, at lower elevations, and on exposed ridges where wind events have stripped much of the seasons snowcover.

Following 12 days of high pressure, the first front crossed the Cascades Friday morning. It wasn't much of a front as the high pressure weakened it significantly, with only a brief period of light rain and snow, New snow accumulations of a trace to 1 inches as of Friday afternoon were common along the east slopes.

There was a mix of precipitation types, from light rain to brief freezing rain along the east approaches to the passes and some lower elevations. The main effect of the light rain or freezing rain where it fell, may have been to destroy some extensive weak surface hoar or near surface facets that have been developing under the recent high pressure. However, if precipitation began as snow Friday these weak snow surfaces may have been buried intact.

The warm and sunny weather over the past 12 days has done a number on the early season snowpack throughout the region, returning many areas to very shallow or snow free early season conditions. The most consistent snowpack remains on shaded northerly aspects in the upper below treeline to near treeline where 2-5 feet remain.

The overall snowpack of 2-5 feet along the east slopes is stable with settled old snow sitting over the strong Thanksgiving rain crust, buried about 1-2 feet. East-side snowdepths are highest in the Washington Pass area and lowest in the southeast zone.

The high pressure, inversion regime over the past 12 days has created a widely varied array of surface snow conditions, including melt freeze crusts, settled old storm snow, and a mix of recently formed surface hoar or near surface facets (sugary snow) at lower elevations and some shaded terrain. 

Reports indicate that in many areas along the east slopes up to about 6000 feet there was extensive recent surface hoar and near surface faceted snow growth. The distribution of these persistent grain types will be an important distinction when greater loading occurs. 

No human-triggered avalanches have been reported in over a week. Some natural small loose wet slides have occurred on mainly steep sun exposed slopes over the last week, but have become much less frequent over the past several days. Active wind loading has not been observed since late last week. 

Observations

North

NCMG was near Washington Pass on north-facing terrain on Wednesday and observed continued development of surface hoar (over 2 cm) below 6000 ft and faceting of the upper snowpack in thin rocky areas in the above treeline zone as well. They report no signs of instability in spite of increasing terrain coverage showing signs of wind effect.

NCMG was in the Washington Pass area on Monday and observed isolated pockets of wind slab to be generally unreactive.  No weak layers were noted in the upper snowpack and widespread and large surface hoar was observed near and below 6000' in non-solar, open terrain. 

Central

No recent observations.

South

No recent observations.