100 PM PST MON FEB 25 2008 WEATHER SYNOPSIS FOR MONDAY AND TUESDAY A weak upper trough and moisture continues to slowly shift to the east of the Cascades on Monday morning. A little west flow aloft and these features have allowed snow to continue a bit longer than expected mainly in the south Cascades. However snow showers mainly in that area should decrease and end on Monday. A shortwave upper ridge and drier air mass should move to the Northwest later Monday and Tuesday. This should lead to fair and dry conditions by Tuesday with a rise in freezing levels. Increasing southwest flow aloft and increasing moisture mainly in the Olympics and north Cascades should be seen as a front approaches Tuesday night. WEATHER FORECAST FOR MONDAY AND TUESDAY * OLYMPICS- Monday morning: Light rain or snow showers decreasing and ending. Monday afternoon and night: Decreasing clouds. Tuesday: Partly cloudy. Tuesday night: Increasing clouds with light rain or snow developing. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST- * CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Monday morning: Light rain or snow showers north and central and light to moderate rain or snow showers south decreasing and ending. Monday afternoon and night: Decreasing clouds. Tuesday: Partly cloudy north and partly sunny central and south. Tuesday night: Increasing clouds with light rain or snow north. * EAST SLOPES WASHINGTON CASCADES- Monday morning: Partly or mostly cloudy north and central and light rain or snow showers south decreasing and ending. Monday afternoon and night: Decreasing clouds. Tuesday: Partly cloudy north and mostly sunny central and south. Tuesday night: Increasing clouds mainly north part. * MT HOOD AREA- Monday morning: Light to moderate rain or snow showers decreasing and ending. Monday afternoon and night: Decreasing clouds. Tuesday: Partly or mostly sunny. Tuesday night: Increasing clouds high clouds. SNOW LEVELS-CASCADE MTNS 3000 ft N, 4000 ft S Mon morn 3500 ft N, 4500 ft S Mon aft and eve FREEZING LEVELS 4000 ft N, 5000 ft C, 7000 ft S Tue morn 5000 ft N, 7000 ft C, 8000 ft S Tue aft and eve SNOW LEVELS-OLYMPIC MTNS 4000 ft Mon and Mon eve FREEZING LEVELS 5000 ft Tue morn 6000 ft Tue aft and eve 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 TUE WED * HURRICANE RIDGE 0 .25 * MT BAKER 0 .25-.5 * WASHINGTON PASS LT .10 LT .25 * STEVENS PASS LT .10 LT .25 * SNOQUALMIE PASS LT .25 LT .25 * MISSION RIDGE 0 0 * CRYSTAL MTN LT .25 LT .10 * PARADISE .25 LT .10 * WHITE PASS LT .10 0 * MT HOOD .25 0 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS W 5-15 Mon aft Light, variable Monday night E 0-10 Tue morn E 5-15 Tue aft and eve * FREE WINDS AT 5000 FT W 5-15 Mon aft and eve SW 5-15 Tue SW 15-25 Tue night strongest north * FREE WINDS AT 9000 FT W 5-15 Mon aft and eve SW 15-25 Tue SW 30-40 Tue night strongest north EXTENDED WEATHER SYNOPSIS FOR WEDNESDAY THROUGH FRIDAY Increased southwest flow and then another upper trough should carry a front across the Northwest on Wednesday morning. This should cause increasing rain and snow in the Olympics and Cascades. Computer models indicated only a brief period of showers and lower snow levels following the front later Wednesday. Another shortwave ridge and drier air mass should move over the Northwest Thursday. This should generally cause fair weather and a rise in freezing levels. Increasing west southwest flow should carry a stronger series of front across the Northwest on Friday and Saturday. This should bring better snowfall in the Olympics and Cascades at lower snow levels. EXTENDED FORECAST FOR WEDNESDAY THROUGH FRIDAY Wednesday morning: Increasing light to moderate rain or snow north to central and increasing light rain or snow south. Wednesday afternoon and evening: Decreasing light snow showers. Thursday: Becoming partly to mostly sunny. Thursday night: Increasing clouds. Friday: Increasing light to moderate rain or snow. * SNOW LEVELS 4-5000 ft N, 6-7000 ft S Wed morn 2-3000 ft N, 5-6000 ft S Wed aft and eve FREEZING LEVELS Rising to 4-5000 ft N, 7-8000 ft S Thu SNOW LEVELS 3-4000 ft N, 5-6000 ft S Fri Lowering Fri aft and night 1-2000 ft N, 2-3000 ft Sat morn