200 PM PST TUE JAN 29 2008 WEATHER SYNOPSIS FOR TUESDAY AND WEDNESDAY The return continues to the active pattern over the northeast Pacific Ocean and Northwest. Strong southwest flow carried a strong front across the Olympics at sunrise and across the Cascades Tuesday mid morning. Strong west flow should carry an upper trough and a cool unstable air mass across the Northwest Tuesday afternoon and evening. This should cause increasing moderate to heavy orographic snow showers at low snow levels. Flow and precipitation is indicated to be heavier in the south Cascades and Mt Hood. The MM5 model indicates strong convergence near Stevens Pass Tuesday evening. A weak short wave ridge and minor surface high pressure should move over the Northwest on Wednesday. This should generally result in decreasing crest level winds and decreasing orographic snow showers on Wednesday. Increasing southwest flow should begin to carry another strong front to the Northwest Wednesday night. This should cause increasing crest level winds and increasing moderate to heavy snow with another minor rise in the low snow levels. WEATHER FORECAST FOR TUESDAY AND WEDNESDAY * OLYMPICS- Tuesday aft and night: Increasing moderate to heavy snow showers heaviest west Olympics. Wednesday morning: Decreasing light to moderate snow showers. Wednesday afternoon: Mostly light snow showers. Wednesday night: Increasing moderate to heavy snow. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST-CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Tuesday aft and night: Increasing moderate to heavy snow showers especially near Stevens in convergence. Wednesday morning: Decreasing light to moderate snow showers. Wednesday afternoon: Mostly light snow showers. Wednesday night: Increasing moderate to heavy snow. * EAST SLOPES WASHINGTON CASCADES- Tuesday aft and night: Increasing light to moderate snow showers especially higher elevations and central Cascades in convergence. Wednesday morning: Decreasing light to moderate snow showers heaviest higher elevations. Wednesday afternoon: Light snow showers mainly higher elevations. Wednesday night: Increasing light to moderate snow. * MT HOOD AREA- Tuesday aft and night: Increasing moderate to heavy snow showers. Wednesday morning: Decreasing light to moderate snow showers. Wednesday afternoon: Mostly light snow showers. Wednesday night: Increasing moderate to heavy snow. SNOW LEVELS-CASCADE MTNS 1000 ft N to S Tue aft Near sea level Tue night and Wed 1000 ft N, 1500 ft S Wed night SNOW LEVELS-OLYMPIC MTNS 1000 ft Tue aft Near sea level Tue night and Wed 1000 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 .75-1 .5 * MT BAKER .75-1 1 * WASHINGTON PASS .5-.75 .25-.5 * STEVENS PASS 1-1.5 .5 * SNOQUALMIE PASS 1.5 .5 * MISSION RIDGE .25-.5 .25 * CRYSTAL MTN .5-.75 .5 * PARADISE 1-1.5 1 * WHITE PASS .75-1 .5 * MT HOOD 1.5-2 1 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS Light variable Tue morn W 15-25 Tue aft and eve W 5-15 Wed Light variable Wed night * FREE WINDS AT 5000 FT SW 40-50 Tue morn strongest south W 30-40 Tue aft and eve strongest south W 20-30 Wed strongest south Increasing to SW 40-60 Wed night strongest south * FREE WINDS AT 9000 FT SW 50-60 Tue morn strongest south W 40-50 Tue aft and eve strongest south W 30-40 Wed strongest south Increasing to SW 50-70 Wed night strongest south EXTENDED WEATHER SYNOPSIS FOR THURSDAY THROUGH SATURDAY Strong southwest flow should carry the next strong front over the Northwest Thursday early morning. This should cause moderate to heavy snow with another minor rise in the low snow levels, as mentioned at the end of the Tuesday- Wednesday synopsis. Strong west flow should carry an upper trough and cool unstable air mass over the Northwest Thursday afternoon and night. This should cause another period of increasing moderate to heavy orographic snow showers at low snow levels. Flow and moisture are indicated to be heaviest again in the south Cascades and Mt Hood area. A larger slower moving upper trough should cross the Northwest on Friday and Saturday. This should cause a period of generally light to moderate snow showers with low snow levels. Flow and moisture continue to be indicated to be heaviest in the south Cascades and Mt Hood area. EXTENDED FORECAST FOR THURSDAY THROUGH SATURDAY Thursday morning: Moderate to heavy snow temporarily decreasing following the front. Thursday afternoon and night: Increasing moderate to heavy orographic snow showers. Friday and Saturday: Periods of light to moderate snow showers. * SNOW LEVELS 1-1500 ft N, 1-2000 ft S Thu Near sea level N to S Fri and Sat