145 PM PST WED JAN 16 2008...UPDATED WEATHER SYNOPSIS FOR WEDNESDAY AND THURSDAY...UPDATED A strong upper level ridge developing about 4-500 miles offshore in forcing most significant storm energy into Alaska, across north-central BC and then southeastward through Alberta and along the northern Rockies early Wednesday. While this is carrying most associated clouds and precipitation well to the north and east of the area, associated weak warm frontal moisture is still moving through the ridge and over the Northwest in an otherwise relatively dry and cool northerly flow aloft. This moisture is producing variable mid and upper level cloudiness over the Olympics and northern part of the Washington Cascades, with clouds and any lower level moisture thinning and decreasing as it moves southward over the remainder of the Washington Cascades and Mt Hood area. With the weak warm front not completely exiting the area until later Wednesday and some residual moisture from a moderate short wave moving weakly over the area later Wednesday night and early Thursday this should bring slowly rising freezing levels and maintain variable mid and high cloudiness in the north- central Washington Cascades and Olympics through early Thursday along with some low clouds in lower terrain along the Cascade west slopes. Further to the south, the clouds should thin and diminish with warming temperatures and considerable sunshine or filtered sunshine likely. After the moderate weather disturbance passes mostly east of the area early Thursday, decreasing clouds are likely in all areas through Thursday night along with generally decreased ridgetop winds. WEATHER FORECAST FOR WEDNESDAY AND THURSDAY...UPDATED * OLYMPICS- Partly cloudy Wednesday afternoon and night with a slight chance of a flurry or light shower, mainly north and northwest slopes. Clouds decreasing Thursday morning becoming mostly sunny and warmer mid-day and Thursday afternoon. Mostly fair Thursday night. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST FROM SNOQUALMIE PASS NORTHWARD- * CASCADE PASSES FROM SNOQUALMIE PASS NORTHWARD, INCLUDING STEVENS, SNOQUALMIE PASSES- * EAST SLOPES WASHINGTON CASCADES FROM SNOQUALMIE PASS NORTHWARD- Considerable mid and high clouds Wednesday afternoon and night except for areas low clouds lower terrain west slopes. Clouds decreasing early Thursday. Mostly sunny and warmer Thursday afternoon. Mostly fair Thursday night. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST SOUTH OF SNOQUALMIE PASS- * CASCADE PASSES SOUTH OF SNOQUALMIE PASS, INCLUDING WHITE PASS- * EAST SLOPES WASHINGTON CASCADES SOUTH OF SNOQUALMIE PASS- Cool with variable mid and high clouds north and variable high clouds south Wednesday afternoon with considerable sunshine or filtered sunshine. Warmer with a few high clouds Wednesday night. Patchy fog lower terrain west slopes early Thursday, otherwise warm with high clouds decreasing Thursday morning. Mostly sunny Thursday afternoon and mostly fair and warm Thursday night. * MT HOOD AREA- Cool with variable high clouds Wednesday afternoon. Warmer with variable high clouds Wednesday night. Warm with variable high clouds decreasing Thursday morning. Mostly sunny and warm Thursday afternoon. Mostly fair Thursday night. SNOW LEVELS-CASCADE MTNS Sea level N and C, 1000 ft S Wednesday afternoon Sea level N and C, 6500 ft S Wednesday night and Thursday morning 1000 ft N, 3000 ft C, 7000 ft S later Thursday morning 5000 ft N, 6000 ft C, 8000 ft S Thursday afternoon 1000 ft N, 5000 ft C, 8000 ft S Thursday night SNOW LEVELS-OLYMPIC MTNS 2000 ft Wednesday afternoon 6000 ft Wednesday night and Thursday morning 7000 ft Thursday afternoon and 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 THU FRI * HURRICANE RIDGE 0 0 * MT BAKER 0 0 * WASHINGTON PASS 0 0 * STEVENS PASS 0 0 * SNOQUALMIE PASS 0 0 * MISSION RIDGE 0 0 * CRYSTAL MTN 0 0 * PARADISE 0 0 * WHITE PASS 0 0 * MT HOOD 0 0 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS Variable mostly W 0-10 Wednesday afternoon W 0-10 Wednesday night and Thursday morning Variable 0-10 Thursday afternoon and night * FREE WINDS AT 5000 FT N-NW 15-25 N, 10-20 S, 20-40 Olympics Wednesday afternoon N-NW 15-30 N, 10-20 S, 25-40 Olympics Wednesday night N-NW 15-30 Cascades, 25-40 Olympics Thursday morning N 15-25 N, 10-20 S, 20-40 Olympics Thursday afternoon N 10-20 Cascades, 15-30 Olympics Thursday night * FREE WINDS AT 9000 FT N-NW 25-40 N, N-NE 20-40 S Wednesday afternoon N-NW 20-40 Cascades, 30-50 Olympics Wednesday night N 25-40 N and Olympics, 15-30 S Thursday morning N 20-40 N and Olympics, 15-25 S Thursday afternoon N-NW 20-40 Thursday night, strongest N and Olympics EXTENDED WEATHER SYNOPSIS FOR FRIDAY THROUGH SUNDAY The dominant blocking ridge should be gradually weakened and flattened by a moderate weather disturbance moving southeastward across the northern Gulf of Alaska Friday, with a part of the ridge moving eastward over the area just ahead of the associated short wave trough. This should maintain mostly sunny skies and relatively high freezing levels, especially in the south and central Cascades and Mt Hood area. However, increasing high clouds ahead of the front should reach the Olympics and northern Washington Cascades by Friday afternoon, with lowering clouds, lowering freezing levels, increasing winds and some light snow expected to develop in the north and Olympics later Friday afternoon and evening. Increasing winds, significant cooling and increasing light to moderate snow should spread southward over the region later Friday night and Saturday morning, becoming briefly moderate later Saturday morning and mid-day. As the east-west oriented upper trough moves south of the area by later Saturday and the upper ridge rebuilds strongly and leans into north-central BC, an associated drier but cold northeasterly flow should spread decreasing showers and slow clearing southward late Saturday into early Sunday. Strengthening and cold northeasterly flow should bring further cooling and increasingly strong east to northeast winds to most areas on Sunday, with clear but cold and windy weather expected to continue Monday. EXTENDED FORECAST FOR FRIDAY THROUGH SUNDAY Mostly fair and relatively warm early to mid Friday. Increasing mid and high clouds and increasing winds spreading into the Olympics and northern Washington Cascades mid-late Friday. Lowering freezing levels, light to moderate snow and increasing winds spreading southward across the region later Friday night and Saturday morning. Cooler with moderate snow decreasing and becoming more showery mid-late Saturday. Light showers decreasing Saturday night north and early-mid Sunday south and becoming colder. Clearing and colder early Sunday north and mid-day Sunday south. Mostly fair, windy and cold later Sunday. * SNOW LEVELS 1-3000 ft N, 4-6000 ft C, 6-8000 ft S early-mid Friday 2-4000 ft N, 3-5000 ft C, 6-8000 ft S late Friday 1-3000 ft N and C, 3-5000 ft S Saturday 1-2000 ft N and C, 2-4000 ft S mid Saturday Sea level to 1000 ft N, 1-2000 ft S late Saturday Sea level N and S Sunday