100 PM PST FRI DEC 7 2007 WEATHER SYNOPSIS FOR THURSDAY AND FRIDAY An upper ridge should generally remain over the northeast Pacific Ocean, with a large weak trough over the western US, through the weekend. A moderate north flow aloft should be over the Northwest coastal waters, with the Olympics and Cascades under the influence of a weaker, cool, mostly dry north flow aloft. Some light showers in the trough on Friday morning will affect the Oregon Cascades, possibly as far north as Mt Hood. A short wave in the north flow aloft over the coastal waters may also enhance as it moves south Friday afternoon and evening. This may continue to enhance the light showers in the trough as far north as Mt Hood. A short wave ridge in the weak, cool north flow aloft over the Olympics and Cascades should cause improved fair weather conditions on Saturday. WEATHER FORECAST FOR THURSDAY AND FRIDAY * OLYMPICS- Friday: Decreasing clouds becoming partly or mostly sunny. Friday night: Partly or mostly clear. Saturday: Mostly sunny. Saturday night: Mostly clear. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST-CASCADE PASSES INCLUDING STEVENS, SNOQUALMIE, WHITE PASSES- Friday: Mostly cloudy. Local valley fog in the morning in the vicinity of the passes. Friday night: Decreasing clouds becoming partly or mostly clear. Saturday: Mostly sunny. Saturday night: Mostly clear. * EAST SLOPES WASHINGTON CASCADES- Friday: Mostly sunny north and mostly cloudy south. Friday night: Decreasing clouds becoming partly or mostly clear. Saturday: Mostly sunny. Saturday night: Mostly clear. * MT HOOD AREA- Friday: Mostly cloudy with possible light snow showers. Friday night: Partly or mostly cloudy with possible light snow showers ending. Saturday: Decreasing clouds becoming partly sunny. Saturday night: Mostly clear. SNOW LEVELS-CASCADE MTNS 1000 ft N and C, 2500 ft S Fri and Fri eve Near sea level N and C, 1500 ft S Sat and Sat night SNOW LEVELS-OLYMPIC MTNS 2000 ft Fri 1000 ft Fri night Near sea level Sat and Sat 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 SAT SUN * HURRICANE RIDGE 0 0 * MT BAKER 0 0 * WASHINGTON PASS 0 0 * STEVENS PASS 0 0 * SNOQUALMIE PASS 0 0 * MISSION RIDGE 0 0 * CRYSTAL MTN 0 0 * PARADISE 0 0 * WHITE PASS 0 0 * MT HOOD LT .10 0 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS E 5-10 Fri and Sat * FREE WINDS AT 5000 FT N-NE 5-15 Fri and Fri eve N-NE 10-20 Sat and Sat eve * FREE WINDS AT 9000 FT N-NW 5-15 Fri N-NW 10-20 Fri night N-NE 10-20 Sat N-NE 15-25 Sat night EXTENDED WEATHER SYNOPSIS FOR SUNDAY THROUGH TUESDAY The cool north flow aloft may increase slightly over the Northwest on Sunday and carry a very weak short wave north to south over the Olympics and Cascades. For this reason we have a slight chance of light snow showers in the forecast for Sunday. The upper ridge over the northeast Pacific Ocean should shift east to over the Northwest on Monday. This should cause another day of fair cool weather in the Olympics and Cascades. The ridge is currently indicated to flatten Tuesday and allow a moderate frontal system to move over the Northwest Tuesday afternoon and evening. EXTENDED FORECAST FOR SUNDAY THROUGH TUESDAY Sunday: Partly cloudy Sunday, with a slight chance of light snow showers mainly near and west of the crest. Sunday night: Decreasing clouds becoming partly or mostly clear. Monday: Partly or mostly sunny. Tuesday morning: Increasing clouds. Tuesday afternoon and evening: Increasing light to moderate snow. * SNOW LEVELS Near sea level N, 1-2000 ft Olys and S Sun and Mon Near sea level N, 2-4000 ft S Tue