130 PM PST SUN JAN 27 2008 WEATHER SYNOPSIS FOR SUNDAY AND MONDAY Mostly mid and high level moisture is streaming northward east of the Cascade crest Sunday afternoon from a frontal band that crossed the area earlier. Most areas of the Olympics and Washington Cascades have seen occasional light snow showers through the day Sunday with the steady precipitation under the front now ended over the Mt Hood area Sunday afternoon. Cool unstable air offshore associated with an upper level trough is gradually moving inland and spread increasing snow showers over the region through Sunday night at snow levels near the sea level. Showers should tapper off by early Monday as a brief upper ridge shifts over the area. The next strong frontal system should develop Monday and begin to affect the area overnight Monday. Increasing light to moderate precipitation is expected Monday night as the frontal moisture spreads inland. This system should cause increasing winds and very limited warming with snow levels remaining below 1000 feet. WEATHER FORECAST FOR SUNDAY AND MONDAY * OLYMPICS- Sunday afternoon and evening: Increasing light to occasionally moderate snow showers. Sunday night and Monday morning: Decreasing occasional light snow showers. Monday afternoon and evening: Increasing light snow. Monday night: Increasing light to moderate snow. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST- Sunday afternoon and evening: Increasing light to occasionally moderate snow showers. Sunday night and Monday morning: Decreasing occasional light snow showers. Monday afternoon and evening: Light snow developing by late afternoon and gradually increasing. Monday night: Increasing light to moderate snow. * CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Sunday afternoon and evening: Increasing light to occasionally moderate snow showers. Sunday night and Monday morning: Decreasing occasional light snow showers. Monday afternoon and evening: Light snow developing by late afternoon and gradually increasing. Monday night: Increasing light to moderate snow. * EAST SLOPES WASHINGTON CASCADES- Sunday afternoon and evening: Increasing light to occasionally moderate snow showers. Sunday night and Monday morning: Decreasing occasional light snow showers. Monday afternoon and evening: Light snow developing by evening. Monday night: Increasing light to occasionally moderate snow, mainly near the crest. * MT HOOD AREA- Sunday afternoon and evening: Light to occasionally moderate snow showers. Sunday night and Monday morning: Decreasing occasional light snow showers. Monday afternoon and evening: Light snow developing by late afternoon and gradually increasing. Monday night: Increasing light to moderate snow. SNOW LEVELS-CASCADE MTNS Near sea level N to C, 500 ft S Sun aft Near sea level N to S Sun night through Mon night SNOW LEVELS-OLYMPIC MTNS Near sea level Sun aft through 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 LT .25 .25-.5 * MT BAKER .25 .25-.5 * WASHINGTON PASS LT .25 .25 * STEVENS PASS .25 .25-.5 * SNOQUALMIE PASS .25 .25-.5 * MISSION RIDGE LT .25 LT .25 * CRYSTAL MTN .25 .25 * PARADISE .25 .25-.5 * WHITE PASS .25 .25-.5 * MT HOOD .25-.5 .25-.5 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS W 5-10 Sun aft through Mon morn W 5-15 Mon aft and night E 0-10 late Mon night * FREE WINDS AT 5000 FT NW 5-10 N, W 5-15 C, W-NW 10-20 S Sun aft and night W 5-15 N and C, W 20-30 Mon morn W 15-30 Mon aft, strongest south part SW 20-30 N and C, SW 35-50 S Mon night * FREE WINDS AT 9000 FT W 10-20 Sun aft W-NW 10-20 Sun night and Mon morn NW 15-30 Mon mid day W 25-35 Mon aft and night EXTENDED WEATHER SYNOPSIS FOR TUESDAY THROUGH THURSDAY A strong cold front should move across the Olympics and Cascades Tuesday morning. This should cause a period of moderate to heavy precipitation at low freezing levels and very strong winds. Behinds the front later Tuesday strong flow should maintain orographic precipitation along the west slope areas and likely convergence affects near the usual central Cascade areas. A short wave ridge should move over the Pacific Northwest Wednesday with weak surface high pressure building over the areas. This should cause decreasing light snow showers Wednesday becoming scattered in nature. Another strong front should move across the area in westerly flow Thursday morning. This should be similar to the Tuesday front with a period of heavy snow at low freezing levels and very strong winds early Thursday morning. Moderate to heavy showers in strong flow behind the frontal passage should persist through the day Thursday before tapering Thursday night. EXTENDED FORECAST FOR TUESDAY THROUGH THURSDAY Tuesday: Moderate to heavy snow early. Snow changing to light to moderate snow showers Tuesday midday. Light to moderate snow showers Tuesday afternoon decreasing overnight. Wednesday: Decreasing light snow showers. Thursday: Increasing moderate to heavy snow early Thursday. Moderate snow showers Thursday afternoon, decreasing Thursday night. * SNOW LEVELS Near sea level 1000 ft N to S Tue to Wed 1-3000 ft N and S Thur