Heads up! NWAC issued an out of season avy forecast/warning for this weekend (below).
Backcountry Avalanche Forecast
WA Cascades near and west of crest - north of Stevens Pass
Northwest Weather and Avalanche Center Seattle Washington
1351 PM PDT Fri May 04 2012
This forecast applies to back country avalanche terrain below 7000 feet and does not apply to developed ski areas or highways.
Please note that regular forecasts for this season have ended. Special forecasts will be issued this spring only if unusually severe avalanche conditions develop.
This special forecast applies from Friday May 4th through Tuesday May 8th and will be updated as conditions warrant.
Weather Service ID
Forecast
Friday Through Tuesday: Strong spring storms this week have deposited significant new snow amounts above about 5 to 6000 feet. This snow should become increasingly unstable through the weekend into early next week with gradually increasing sunshine and warming expected. Expect locally high avalanche danger developing above about 5 to 6000 feet, especially on sun exposed terrain and higher elevations and on the volcanoes.
Snowpack Analysis
Recent Weather: Several strong fronts and associated upper level troughs have moved across the Pacific Northwest since Sunday. Snow levels have remained relatively low throughout the week mainly near 3-4000 feet in the north Cascades and 4 to 5000 feet in south Cascades and Mt Hood area.
Total precipitation amounts over the past four days (Monday through early Friday morning) along most west slope areas and volcanoes range from about 2 to 3 inches of water equivalent with Timberline on Mt Hood receiving the greatest amount of 4.5 inches in four days and 5.2 inches in 5 days! Less water was received along the east slopes, mostly between .5 to 1 inch. This precipitation has mainly been in the form of snow above 4000 feet in the north and 5000 feet in the south.
Recent snowfall totals during the week range from 1 to 2 feet of snow at study plots from 4-6000 feet. Significantly greater new snow is likely above 6-7000 feet, especially on the volcanic peaks.
Snow Pack and Avalanche Activity: There have been numerous field observations over the past several days, especially from WSDOT crews working above Chinook Pass in the central WA Cascades and from patrol at Alpental and Mt Hood Meadows ski areas. Crews on Chinook Pass reported by early afternoon Thursday, they had already received about 15 inches of new snow through the day. This new snow became increasingly wet and unstable through the afternoon with natural slides releasing on most slopes even with mostly cloudy and cool conditions. Slides were also releasing on relatively low angled slopes of about 30 degrees, with most slides remained above a thin crust layer.
However of potentially greater concern is the snowpack below the recent snow and thin crust layer. Below the new recent snow and any remaining thin crust, about 1 to 2 meters of large grain wet to saturated snow remains above the older finer grained winter snowpack. Control results and cornice drops earlier in the week did produce some larger wet slab releases involving these deep layers of wet snow.
Other field observations from both Alpental and Mt Hood Thursday as well as back country skier reports this week confirm the deep layer of wet unconsolidated snow ranging from 1 to 2 meters.
Just received snowpack conditions from Alpental pro patrol Friday morning. New recent snow becoming wet with ski cuts easily triggering wet avalanches. These slides are running far and fast and entraining wet snow underneath as well as carrying over shallow angled terrain and benches.
What does this mean? It means we do not have a stable spring snowpack as yet. It also means that slides releasing easily in the new snow from this week, up to 1 to 2 feet or more, may break down and involve the deeper 3 to 6 feet of wet snow layers. These slides would become very large very quickly, travel fast and far and be potentially destructive!
Cornice failures also remain a major concern, as these may trigger large wet slab releases on slopes below.
Backcountry Avalanche Forecast
WA Cascades near and west of crest - north of Stevens Pass
Northwest Weather and Avalanche Center Seattle Washington
1351 PM PDT Fri May 04 2012
This forecast applies to back country avalanche terrain below 7000 feet and does not apply to developed ski areas or highways.
Please note that regular forecasts for this season have ended. Special forecasts will be issued this spring only if unusually severe avalanche conditions develop.
This special forecast applies from Friday May 4th through Tuesday May 8th and will be updated as conditions warrant.
Weather Service ID
Forecast
Friday Through Tuesday: Strong spring storms this week have deposited significant new snow amounts above about 5 to 6000 feet. This snow should become increasingly unstable through the weekend into early next week with gradually increasing sunshine and warming expected. Expect locally high avalanche danger developing above about 5 to 6000 feet, especially on sun exposed terrain and higher elevations and on the volcanoes.
Snowpack Analysis
Recent Weather: Several strong fronts and associated upper level troughs have moved across the Pacific Northwest since Sunday. Snow levels have remained relatively low throughout the week mainly near 3-4000 feet in the north Cascades and 4 to 5000 feet in south Cascades and Mt Hood area.
Total precipitation amounts over the past four days (Monday through early Friday morning) along most west slope areas and volcanoes range from about 2 to 3 inches of water equivalent with Timberline on Mt Hood receiving the greatest amount of 4.5 inches in four days and 5.2 inches in 5 days! Less water was received along the east slopes, mostly between .5 to 1 inch. This precipitation has mainly been in the form of snow above 4000 feet in the north and 5000 feet in the south.
Recent snowfall totals during the week range from 1 to 2 feet of snow at study plots from 4-6000 feet. Significantly greater new snow is likely above 6-7000 feet, especially on the volcanic peaks.
Snow Pack and Avalanche Activity: There have been numerous field observations over the past several days, especially from WSDOT crews working above Chinook Pass in the central WA Cascades and from patrol at Alpental and Mt Hood Meadows ski areas. Crews on Chinook Pass reported by early afternoon Thursday, they had already received about 15 inches of new snow through the day. This new snow became increasingly wet and unstable through the afternoon with natural slides releasing on most slopes even with mostly cloudy and cool conditions. Slides were also releasing on relatively low angled slopes of about 30 degrees, with most slides remained above a thin crust layer.
However of potentially greater concern is the snowpack below the recent snow and thin crust layer. Below the new recent snow and any remaining thin crust, about 1 to 2 meters of large grain wet to saturated snow remains above the older finer grained winter snowpack. Control results and cornice drops earlier in the week did produce some larger wet slab releases involving these deep layers of wet snow.
Other field observations from both Alpental and Mt Hood Thursday as well as back country skier reports this week confirm the deep layer of wet unconsolidated snow ranging from 1 to 2 meters.
Just received snowpack conditions from Alpental pro patrol Friday morning. New recent snow becoming wet with ski cuts easily triggering wet avalanches. These slides are running far and fast and entraining wet snow underneath as well as carrying over shallow angled terrain and benches.
What does this mean? It means we do not have a stable spring snowpack as yet. It also means that slides releasing easily in the new snow from this week, up to 1 to 2 feet or more, may break down and involve the deeper 3 to 6 feet of wet snow layers. These slides would become very large very quickly, travel fast and far and be potentially destructive!
Cornice failures also remain a major concern, as these may trigger large wet slab releases on slopes below.
