####018006178#### WWUS86 KPQR 241909 SABOR Summary Avalanche Forecast for Mt Hood area Northwest Weather and Avalanche Center Seattle Washington 1108 AM PST Fri Feb 24 2012 This forecast applies to back country avalanche terrain below 7000 feet and does not apply to developed ski areas or highways. Avalanche Forecast Mt Hood Area- ...AVALANCHE WARNING FOR SATURDAY... Friday and Friday night: Considerable danger on lee slopes above 6000 feet and moderate elsewhere slightly increasing Friday morning and mid-day and substantially increasing later Friday afternoon and night...becoming high on lee slopes above 6000 feet and increasing considerable elsewhere. Saturday and Saturday night: High avalanche danger above 6000 feet and increasing considerable below early Saturday further increasing and becoming high above 6000 feet and on lee slopes above 5000 feet and increasing considerable elsewhere. Back country travel is not recommended. Sunday Outlook: High avalanche danger above 6000 feet and on lee slopes above 5000 feet early Sunday. Danger slowly decreasing Sunday and Sunday night, becoming high above 6000 feet and considerable below late Sunday. Dangerous avalanche conditions should continue...especially in wind loaded terrain. Snowpack Synopsis In most areas very light amounts of low density snowfall were received on Thursday. This dusting of new snow fell over moderate amounts of decreasing density snowfall received on Wednesday which arrived on the heels of heavy amounts of either wet heavy snow or rain on Tuesday. Along with very slowly decreasing winds and low and lowering freezing levels, this weather allowed the old wet or moist snow layers to slowly refreeze and strengthen while depositing small to moderate amounts of new and colder snow over the old refreezing snowpack. Due to this refreezing and strengthening Wednesday and Thursday, widespread avalanching on Tuesday and Wednesday and significant settlement of the large amounts of snow received last Friday and Saturday, an overall slow decrease in the danger has occurred late Wednesday thru early Friday. However, recent wind effects have slightly enhanced the danger from the recent colder snowfall on lee slopes where some shallow slabs lie over the refreezing crust or over firmer and strengthening snow layers...especially on north through east exposures above about 5 to 6000 feet. However, in higher elevation wind exposed terrain a strong refrozen crust or ice layer is producing relatively stable surface snow. Friday and Friday night Clouds and light snow showers should briefly decrease Friday morning along with slow warming and some sunshine. This should produce a brief danger increase on sun exposed slopes where the potential for small loose slides or isolated shallow slabs should increase, along with some cornice activity. However increasing clouds and winds are likely Friday afternoon with significant cooling and increasing moderate rain or snow arriving late Friday afternoon and evening. This weather should produce a more general and substantial danger increase. Moderate to heavy snowfall, strong cooling and strengthening winds overnight should produce thickening wind slabs and a further danger increase...especially on wind loaded terrain. Saturday and Saturday night Moderate to heavy snow or snow showers are expected for most of Saturday with heavy accumulations likely. Along with low and lowering freezing levels and strong ridgetop and pass winds, this weather should create progressively larger and more unstable wind slabs.. with associated high danger slowly spreading to lower elevations especially on any wind loaded terrain. Due to the increasingly dangerous avalanche conditions likely Saturday, back country travel in avalanche terrain is not recommended, especially on mid and higher elevation terrain showing evidence of wind transport. In some ways, this weather situation is similar to those conditions experienced late last week and weekend, when heavy snow loading produced widespread avalanching, many human triggered avalanches, and several avalanche related fatalities in the Washington Cascades. Please let's not repeat any of those sad events. Look at the snowpack objectively and communicate with other members of your party. Know that the snowpack cares little about your experience, skill level or the amount of safety equipment in your party. In short, use your brain and not your equipment to mitigate the danger and choose safe routes. Choice not chance produces most avalanche accidents! Sunday Outlook Although light to moderate showers should briefly decrease Sunday morning, a final weather disturbance should swing southward along the coast during the day...producing a slight increase in showers or light snow in the Mt Hood area during the afternoon and evening hours. Along with relatively cold temperatures, very low freezing levels and generally diminishing or light winds, this weather should allow for a very slow decrease in the existing considerable to high danger. While the weather should become increasingly inviting for BC travel, the avalanche conditions will not be nearly as nice. In fact, significant unstable wind slab conditions are likely to persist on any wind loaded terrain, where human triggered wind slabs of 2-3 feet or more should remain likely. 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. Moore/Northwest Weather and Avalanche Center Seattle Washington References 1. http://www.nwac.us/