200 PM PST TUE JAN 8 2008 WEATHER SYNOPSIS FOR TUESDAY AND WEDNESDAY Another frontal passage raced across the Cascades Tuesday morning producing a period of moderate to heavy precipitation over most areas of the Olympics and both east and west of the Cascade crest. Most areas of the Cascades and Olympics experienced a lull in shower activity form late morning Tuesday into the afternoon. However over Mt Hood where a small scale feature has enhanced early Tuesday, heavy snowfall has continued through the day. Freezing levels have pushed upwards through the day Tuesday, but are remaining relatively low overall. A large area of cold unstable showers offshore is quickly approaching the coastal areas Tuesday afternoon. An upper level trough axis should usher these showers into the area Tuesday evening and overnight. This should bring renewed moderate to heavy snow showers at significant cooling along with strengthening westerly flow overnight and early Thursday. A brief building upper ridge offshore behind the trough should gradually shift across the region during the day Wednesday. This should allow for significantly decreasing winds and a brief end to precipitation from about midmorning Wednesday through Wednesday evening. Another approaching warm frontal system should be directed directly towards the Pacific Northwest Wednesday night and begin spreading increasing winds and precipitation across the Olympics and Cascades by late Wednesday night and early Thursday. WEATHER FORECAST FOR TUESDAY AND WEDNESDAY * OLYMPICS- Tuesday: Light to moderate snow showers afternoon and evening. Tuesday night: Increasing moderate to heavy snow showers. Wednesday: Light snow showers early, diminishing or ending late morning. Partly cloudy Wednesday afternoon. Increasing clouds Wednesday evening. Wednesday Night: Increasing light rain or snow becoming moderate late. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST- * CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Tuesday: Light to moderate snow showers afternoon and evening. Tuesday night: Increasing moderate to heavy snow showers. Wednesday: Light snow showers early, diminishing or ending late morning. Becoming partly cloudy Wednesday afternoon. Increasing clouds Wednesday evening. Wednesday Night: Increasing light rain or snow becoming moderate late. * EAST SLOPES WASHINGTON CASCADES- Tuesday: Light snow showers afternoon and evening. Tuesday night: Increasing light to moderate snow showers especially higher elevations and nearer the crest. Wednesday: Showers ending with partial clearing late morning through evening. Wednesday night: Increasing clouds with light snow developing late night. * MT HOOD AREA- Tuesday: Moderate to heavy snow showers. Tuesday night: Briefly decreasing showers Tuesday evening but increasing moderate to heavy snow showers late. Wednesday: Light snow showers early, diminishing or ending late morning. Becoming partly cloudy Wednesday afternoon. Increasing clouds Wednesday evening. Wednesday Night: Increasing light rain or snow becoming moderate late. SNOW LEVELS-CASCADE MTNS 1000 ft N, 3500 ft S Tue aft and eve 1500 ft N and S Tue night 500 ft N and S Wed morning 1000 ft N, 2000 ft S Wed aft and evening 2000 ft N, 2500 ft C, 3000 ft S Wed night SNOW LEVELS-OLYMPIC MTNS 2500 ft Tue aft and eve 500 ft Wed morn 1000 ft Wed aft 2500 ft Wed 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 WED THU * HURRICANE RIDGE .5-.75 .25 * MT BAKER 1 .25-.5 * WASHINGTON PASS .5 .25 * STEVENS PASS .75 .25-.5 * SNOQUALMIE PASS .75-1 .25-.5 * MISSION RIDGE .25-.5 LT .25 * CRYSTAL MTN .75 .25-.5 * PARADISE .75-1 .25-.5 * WHITE PASS .5-.75 .25 * MT HOOD 1.5 .25-.5 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS E 0-10 Tue aft and eve W 10-20 Tue night and early Wed W 5-15 Wed aft E 0-10 Wed night * FREE WINDS AT 5000 FT SW 15-25 N, SW 20-30 C, W-SW 25-35 S Tue midday and aft W-SW 30-40 Tue night W 20-30, N and C, W-NW 25-40 S Wed morn SW 5-15 N and C, W-SW 15-25 S Wed aft and eve SW 30-40 Wed night * FREE WINDS AT 9000 FT SW 25-40 Tue midday through Tue eve W-SW 30-45 Tue night W-NW 30-40 Wed morn W-NW 15-25 Wed mid morn and aft SW 30-45 Wed night EXTENDED WEATHER SYNOPSIS FOR THURSDAY THROUGH SATURDAY A strong frontal passage is expected Thursday morning across the area causing heavy precipitation at rising freezing levels along with very strong southwesterly crest level flow. The strong westerly jet stream in the eastern north Pacific should maintain strong showers behind the front and maintain orographic precipitation along the west slopes Thursday night into early Friday. An upper trough should move across the Cascades early Friday to maintain periods of moderate precipitation at slightly cooler temperatures. A rebuilding ridge of high pressure offshore should allow for decreasing precipitation and gradual clearing later Friday through Saturday. EXTENDED FORECAST FOR THURSDAY THROUGH SATURDAY Thursday morning: Moderate to heavy rain or snow, changing to showers midday. Thursday midday to Thursday night: Moderate to heavy rain or snow showers west slopes, scattered light showers east slopes. Friday morning: Light to moderate snow showers gradually decreasing. Friday afternoon and evening: Partly to mostly cloudy. Saturday: Mostly cloudy with a chance of light showers, mainly crest and north part. * SNOW LEVELS 1500-3000 ft N, 2500-3500 ft S Thursday 2-3000 ft N, 3-4000 ft S Friday 3-4000 ft N, 4-5000 ft S Saturday