0800 AM PDT SUN DEC 09 2007 && ZONE AVALANCHE FORECASTS * OLYMPICS, WASHINGTON CASCADES- Moderate avalanche danger above 5000 feet and low below slightly increasing Sunday, mainly in the north. Moderate avalanche danger above 5000 feet and low below Sunday night. Slightly decreasing danger Monday and Monday night. * MT HOOD AREA Moderate avalanche danger above 5000 feet and low below slightly increasing Sunday. Moderate avalanche danger above 5000 feet and low below Sunday night. Slightly decreasing danger Monday and Monday night. SNOWPACK ANALYSIS In most areas, small amounts of either relatively low density snow or surface hoar exist over a generally shallow snowpack and relatively strong crust formed following the heavy flooding rain event early last week. Recent snow amounts over this crust vary from about 6 to 10 inches in the northern Washington Cascades, a trace to a few inches in the Olympics, central and southern Washington Cascades, and about 4-7 inches in the Mt Hood area. Varying winds during and after these small amounts of snow developed some localized pockets of unstable wind slab ranging up to 6 to 12 inches over the crust above about 5000 feet, with most recent winds producing local wind slabs on south and southwest exposures. Field reports of explosive controlled slides indicate that while small, the slabs that do release have been running relatively far on the hard crusty surface. Also, the recent and intermittently clear and cool weather has allowed for varying amounts of surface hoar to develop over either the crust or low density snow over the crust, as well as some faceting both near or just above the crust or below the crust near the ground in the unusually shallow snow cover. At lower elevations, the recent rainfall and resultant widespread avalanche cycle produced a patchy snowcover in some areas, especially in avalanche terrain where slides released to near the ground. Also, melt and snowpack settlement have allowed for a return to significant vegetative and terrain anchoring of the otherwise mostly stable snowpack structure below about 5000 feet. DETAILED FORECASTS SUNDAY, SUNDAY NIGHT, MONDAY, MONDAY NIGHT Increasing clouds should spread southward early Sunday, with occasional light snow developing in the Olympics and north Cascades during the morning reaching the central Cascades by later morning. However, only briefly increased clouds are expected to reach the southern Cascades and Mt Hood area. Light snow or snow showers should slowly decrease in the north and central Cascades Sunday afternoon and night, with further decreasing clouds and light showers Sunday night. Then partly cloudy skies early Monday should give way to mostly sunny skies later Monday morning and afternoon. Relatively low freezing levels are also expected to continue in most areas Sunday through Monday morning, with a slight rise likely later Monday. Along with slightly and briefly increasing ridgetop winds Sunday into early Monday, this weather should allow for a slight increase in the avalanche danger Sunday, mainly in the north, but a slight decrease in the danger on Monday. While little or no significant accumulations are expected, the bond of any new snow to the old snow surface should be rather poor, and the new snow should be quite susceptible to wind transport over the crusted older snow surface. Hence small pockets of unstable slabs should continue above about 5000 feet, with expected winds shifting these localized pockets to a variety of exposures over the next 24-48 hours. At lower elevations, the combination of light winds, a very shallow and in places patchy snow cover, and significant terrain and vegetative anchoring should all help to maintain a generally low danger and stable snowpack structure. However, it should be noted that this weather should allow for further surface hoar formation as well as continued faceting and weakening of both the crust region and the bond of recent new snow to the old decomposing crust surface. These may be important factors when future heavier snow loading occurs. &&