100 PM PST SUN JAN 13 2008 WEATHER SYNOPSIS FOR SUNDAY AND MONDAY A front crossed the Olympics and Cascades on Saturday and caused several inches of new snow at most sites near and west of the Cascade crest. Light snow showers lingering mainly over the Cascade west slopes were ending early Sunday. A short wave ridge and surface high pressure should move over the west US on Sunday. This should cause lighter crest level winds, fair weather and rising freezing levels in the Olympics and Cascades on Sunday. Some higher freezing levels were seen in the sounding at Forks and Salem on Sunday morning so temperatures should warm up at many sites on Sunday. A developing offshore surface flow should cause cooler temperatures in the lower Cascade passes Sunday afternoon. A short wave trough and front should move through the building ridge and over the Northwest Monday afternoon. This should cause increasing crest level winds and increasing clouds by Monday morning. The front should cross the Olympics Monday midday and the Cascades Monday afternoon. Snow levels should rapidly lower as the front moves over the area. A lack of precipitation in advance of the front and the rapidly lowering snow levels dont seem to favor freezing rain at the Cascade passes. Orographic snow showers should be seen Monday evening and convergence may enhance snow showers in the central Cascades. WEATHER FORECAST FOR SUNDAY AND MONDAY * OLYMPICS- Sunday afternoon: Mostly sunny. Sunday night: Increasing clouds. Monday morning: Light rain or snow. Monday midday and afternoon: Moderate to heavy rain or snow. Monday evening: Light to moderate snow showers heaviest west Olympics. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST- Sunday afternoon: Mostly sunny. Sunday night: Partly clear. Monday morning: Increasing clouds initially north part. Monday midday: Light rain or snow north and cloudy south. Monday afternoon: Moderate to heavy rain or snow north and light to moderate rain or snow south. Monday evening: Light to moderate snow showers possibly heaviest central Cascades. * CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Sunday afternoon: Mostly sunny, some fog lower east approaches. Sunday night: Partly clear, some fog continuing lower east approaches. Monday morning: Increasing clouds initially Stevens and Snoqualmie. Monday midday: Light snow mainly Stevens and Snoqualmie. Monday afternoon: Moderate snow. Monday evening: Light to moderate snow showers heaviest Stevens and Snoqualmie. * EAST SLOPES WASHINGTON CASCADES- Sunday: Mostly sunny with fog lower elevations. Sunday night: Partly clear with some fog continuing lower elevations. Monday morning: Increasing clouds initially north part. Monday midday: Light snow north and cloudy south. Monday afternoon: Light to moderate snow north and light snow south. Monday evening: Light to moderate snow showers possibly heaviest central Cascades. * MT HOOD AREA- Sunday: Sunny. Sunday night: Mostly clear. Monday morning and midday: Increasing clouds. Monday afternoon: Light to moderate rain or snow. Monday evening: Light to moderate snow showers. FREEZING LEVELS-CASCADE MTNS 3000 ft N, 5000 ft S Sun midday 4000 ft N, 7000 ft S Sun aft 5000 ft N, 8000 ft S Sun eve SNOW LEVELS 5000 ft N, 7000 ft S Mon morn 4000 ft N, 6000 ft S Mon midday except near the surface Cascades passes and east slopes through Monday midday 2000 ft N, 4000 ft S Mon aft rising to free air levels passes 1000 ft N and S Mon night FREEZING LEVELS-OLYMPIC MTNS 4000 ft Sun midday 6000 ft Sun aft 7000 ft Sun eve SNOW LEVELS 7000 ft Mon morn 5000 ft Mon midday 2000 ft Mon aft 1000 ft Mon night Cascade Snow/Freezing Levels refer to the northern Washington Cascades (N) through Mt Hood area (S). Central Washington Cascade snow levels (typically near Snoqualmie Pass) are normally midway between indicated N and S levels. Note that surface snow/freezing levels are common near the passes during easterly pass flow and may result in multiple snow/freezing levels. 24 HOUR FORECAST OF PRECIPITATION IN INCHES OF WATER EQUIVALENT ENDING AT 4AM MON TUE * HURRICANE RIDGE 0 .5 * MT BAKER 0 1 * WASHINGTON PASS 0 .5 * STEVENS PASS 0 .5 * SNOQUALMIE PASS 0 .75 * MISSION RIDGE 0 LT .25 * CRYSTAL MTN 0 .25-.5 * PARADISE 0 .5-.75 * WHITE PASS 0 .25-.5 * MT HOOD 0 .5 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS E 0-10 Sun aft E 5-15 Mon morn Changing Mon aft W 10-20 Mon eve * FREE WINDS AT 5000 FT SW 10-20 Sun aft and eve SW 20-30 Mon morn strongest Olympics and north Cascades SW 20-40 Mon aft W 25-35 Mon eve * FREE WINDS AT 9000 FT SW 20-30 Sun aft and eve strongest Olympics and north Cascades SW 30-50 Mon morn strongest Olympics and north Cascades SW 50-70 Mon aft W 50-60 Mon eve EXTENDED WEATHER SYNOPSIS FOR TUESDAY THROUGH THURSDAY The significant pattern change should continue in the extended period. A large upper ridge should build over the northeast Pacific Ocean and a large area of surface high pressure and dry air mass should build over the northeast Pacific Ocean and Northwest. This should start a fair weather period of up to several days beginning later Tuesday in the Northwest. EXTENDED FORECAST FOR TUESDAY THROUGH THURSDAY Tuesday: Light snow showers ending with partial clearing. Wednesday and Thursday: Mostly sunny days and mostly clear nights. * FREEZING LEVELS Near sea level N and S Tue Rising to 1-2000 ft N, 5-7000 S Wed Rising to 3-5000 ft N, 7-9000 ft S Thu except remaining near the surface Cascade passes and east slopes Wed and Thu