130 PM PST WED JAN 30 2008 WEATHER SYNOPSIS FOR TUESDAY AND WEDNESDAY The active pattern over the northeast Pacific Ocean is sending very strong storms across the Northwest. A strong front crossed the Olympics and Cascades on Tuesday morning, followed by strong orographic west flow and a cool unstable air mass Tuesday afternoon and night. This caused heavy new snow with 15-20 inches at most sites near and west of the crest. A weak short wave ridge and minor surface high pressure should move over the Northwest on Wednesday. This should result in minor relative break with decreasing west crest level winds and decreasing snow showers. Increasing southwest flow should carry another very strong front to the Northwest Wednesday night. This should be accompanied in the Olympics and Cascades by more very strong crest level winds and increasing moderate to heavy snow with a minor rise in the low snow levels. The front should again be followed Thursday by strong orographic west flow and a cool unstable air mass Thursday and Thursday night. This should again cause heavy new snow at most sites near and west of the Cascade crest. Winds and snow are again indicated to be heaviest in the south Cascades and Mt Hood area. Another avalanche cycle is also expected Wednesday night and Thursday. WEATHER FORECAST FOR TUESDAY AND WEDNESDAY * OLYMPICS- Wednesday afternoon: Mostly light snow showers. Wednesday night and Thursday morning: Increasing moderate to heavy snow. Thursday afternoon and evening: Moderate to heavy snow showers. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST-CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Wednesday afternoon: Mostly light snow showers. Wednesday night and Thursday morning: Increasing moderate to heavy snow. Thursday afternoon and evening: Moderate to heavy snow showers. * EAST SLOPES WASHINGTON CASCADES- Wednesday afternoon: Light snow showers. Wednesday night and Thursday morning: Increasing light to moderate snow. Thursday afternoon and evening: Moderate snow showers especially higher elevations. * MT HOOD AREA- Wednesday afternoon: Light to moderate snow showers. Wednesday night and Thursday morning: Increasing moderate to heavy snow. Thursday afternoon and evening: Moderate to heavy snow showers. SNOW LEVELS-CASCADE MTNS 500 ft N, 1000 ft S Wed 1000 ft N, 2000 ft S Wed night and Thu morn 500 ft N, 1000 ft S Thu aft and night SNOW LEVELS-OLYMPIC MTNS 1000 ft Wed 1500 ft Wed night and Thu morn 1000 ft Thu aft 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 .75 .75 * MT BAKER 1 1 * WASHINGTON PASS .75 .75 * STEVENS PASS .75 1 * SNOQUALMIE PASS 1 1-1.5 * MISSION RIDGE .25 .25-.5 * CRYSTAL MTN .5-.75 .5-.75 * PARADISE 1-1.5 1-1.5 * WHITE PASS .75-1 .75-1 * MT HOOD 1.5 1.5 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS W 10-20 Wed aft W 15-30 Wed night and Thu morn W 10-20 Thu aft and night * FREE WINDS AT 5000 FT SW 20-35 Wed aft SW 40-60 Wed night W 25-35 N, W 35-45 S Thu W 15-25 N, W 25-35 S Thu eve * FREE WINDS AT 9000 FT SW 30-50 Wed aft SW 50-70 Wed night W 30-40 N, W 40-60 S Thu W 20-30 N, W 30-50 S Thu eve EXTENDED WEATHER SYNOPSIS FOR FRIDAY THROUGH SUNDAY A broad upper trough and cool flow should be seen over the Northwest Friday and this weekend. Weaker flow and a minor surface high pressure should move over the Northwest late Friday. This should cause decreasing snow showers in the Olympics and Cascades. A short wave, surface low pressure system and front should directly cross the Northwest Saturday night and Sunday morning. The main northwest flow should be over Oregon and California. This should cause a period of at least moderate snow in the Olympics and Cascades. Cool northwest flow should be seen later Sunday while surface high pressure begins to build over the Northwest. This should generally cause decreasing light snow showers over the Olympics and Cascades. EXTENDED FORECAST FOR FRIDAY THROUGH SUNDAY Friday morning: Decreasing light to moderate snow showers heaviest near and west of the crest. Friday afternoon to Saturday morning: Mostly cloudy with occasional light snow showers. Saturday afternoon to Sunday morning: Increasing moderate snow. Sunday afternoon and night: Decreasing light snow showers heaviest near and west of the crest. * SNOW LEVELS Near sea level-1000 ft N, 1-2000 ft S Fri to Sun