####018005801#### WWUS86 KSEW 092138 SABWA Summary Avalanche Forecast for Olympics and Washington Cascades Northwest Weather and Avalanche Center Seattle Washington 1338 PM PST Fri Mar 09 2012 This forecast applies to back country avalanche terrain below 7000 feet and does not apply to developed ski areas or highways. Avalanche Forecast Olympics- Washington Cascades near and west of the crest, north of Stevens Pass, including Mt Baker area- ...Avalanche Watch issued for Saturday... Friday: High avalanche danger above 5000 feet and considerable below and increasing by later Friday. Further significantly increasing danger Friday night. Saturday: High avalanche danger above 4000 feet and considerable below, gradually increasing. Further slightly increasing danger Saturday night. Sunday Outlook: High avalanche danger above 4000 feet and considerable below and increasing. Further slowly increasing danger Sunday night. Washington Cascades near and west of the crest from Stevens Pass southward- Friday: Moderate avalanche danger below 7000 feet slowly decreasing. Gradually increasing danger Friday night. Saturday: Considerable avalanche danger above 4000 feet and moderate below, gradually increasing. Further slightly increasing danger Saturday night. Sunday Outlook: High avalanche danger above 5000 feet on lee slopes and considerable elsewhere and significantly increasing. Further slowly increasing danger Sunday night. Washington Cascades east of the crest- Friday: Moderate avalanche danger above 4000 feet and low below slowly decreasing. Gradually increasing danger Friday night. Saturday: Considerable avalanche danger above 5000 feet on lee slopes and moderate elsewhere, gradually increasing. Further slightly increasing danger Saturday night. Sunday Outlook: Considerable avalanche danger above 5000 feet and moderate below and significantly increasing. Further slowly increasing danger Sunday night. Snowpack Synopsis Recent Weather, Snow Pack and Activity: Dry weather over the past three days has allowed the 7 to 14 inches of storm snow received early this week to settle and stabilize. Very warm temperatures Thursday (yesterday) allowed for further settlement and melt of surface snow as temperatures in the 40-50 F range with strong sunshine. Temperatures remained warm overnight but clearing or strong winds in most areas allowed for a surface crust to form. Shaded northerly aspects may still have some settled powder snow as recent observations attest. In areas where cloud cover increased overnight, the surface snow may not have refrozen, mainly in the north part. Most areas have a strong crust layer under the recent 7 to 14 inches of snow received early this week. Most recent snowpits and ski tests have observed a moderate bond to this crust layer. . Friday Increasing moderate to occasionally heavy rain or snow at lowering snow levels along with strong winds are expected Friday. The cooling will help to refreeze and stabilize previous wet surface snow forming a new crust layer for new snow to begin loading Friday. This should cause a gradually increasing danger, especially later Friday on steeper lee slopes below ridges. Concern #1: Increasing wind slab development: Moderate snow with lowering snow levels and strong winds Friday and Friday night should build shallow but increasing wind slab layers on many higher elevations lee slopes beginning the increase in the danger as the new storm cycle gets underway. Saturday Moderate snow changing to showers moderate crest level winds and further cooling is expected Saturday as a front crosses the area. Concern #1: Deepening wind slabs on lee slopes and increasing storm slab deposits: Increasing wind slabs should spread to lower elevations and become more extensive on steeper lee slopes mainly ranging from northwest through southeast facing and likely above 4000 feet where wind speeds should be greatest. Previous wet snow should continue to refreeze forming an underlying crust to act as a new bed surface for avalanches. Very dangerous avalanche conditions are expected Saturday and travel in avalanche terrain is not recommended Saturday. Sunday Outlook Increasing moderate to heavy snow cooling and strong winds are expected Sunday as another front is expected to pass early Sunday. Concern #1: Deepening wind slabs on lee slopes or storm slabs at higher elevations. Deeper storm layers should build over earlier deposited storm snow and underlying crust layers or older settled snow. Increasing wind slab layers of 1 to 3 feet are expected by later Sunday, mainly on lee slopes above 4000 feet where natural or triggered slab avalanches will be likely. These unstable layers may also build on cross-loaded ribs and gullies on steeper terrain at lower elevations as well. Very dangerous avalanche conditions are expected to continue Sunday at mid and upper elevations where back country travel in avalanche terrain is not recommended. NWAC weather data and forecasts are also available by calling 206-526-6677 for Washington, 503-808-2400 for the Mt Hood area, or by visiting our Web site at www.nwac.us. Kramer/Northwest Weather and Avalanche Center Seattle Washington References 1. http://www.nwac.us/