145 PM PST FRI FEB 22 2008 WEATHER SYNOPSIS FOR FRIDAY AND SATURDAY A surface and upper level low pressure circulation is ever so slowly moving northward about 100 miles west of the central Washington coast Friday afternoon. This system is weakening and filling and should continue to move slowly northward towards Vancouver Island overnight. The slow movement is mainly due to the lack of upper level flow as the Pacific Northwest remains in a strong split upper level flow pattern. The low offshore did cause a little light precipitation in some areas overnight and early Friday morning but little more is expected out of this system. The low is expected to further weaken over Vancouver Island Saturday. As the low moves north of the area Friday night, a weak onshore flow should develop with a possibility of a little light precipitation at times overnight and in the north early Saturday morning. A high pressure ridge is expected to rebuild over the area later Saturday and Saturday night as the low over Vancouver Island gradually dissipates. This should allow for clearing during the day Saturday and a return to weak offshore flow. Winds should remain relatively light throughout Friday and Saturday in a very weak flow pattern. The strongest flow and associated weather is being directed towards California and this pattern is expected to persist for several days. Another developing low pressure system is expected to approach the offshore waters off northern California Saturday night. Some moisture rotating around this system may reach the Mt Hood area to cause some light precipitation at times towards early Sunday, however the heaviest precipitation should remain well south of the forecast area. WEATHER FORECAST FOR FRIDAY AND SATURDAY * OLYMPICS- Friday afternoon and evening: Partly to mostly cloudy with a chance of light rain or snow showers. Friday night: Cloudy with possible light rain or snow showers. Saturday morning: Light snow showers ending with partial clearing. Saturday afternoon and evening: Becoming partly cloudy. Saturday night: Increasing high clouds. * WASHINGTON CASCADES- * CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Friday afternoon and evening: Partly cloudy with a chance of light rain or snow showers, mainly north part. Friday night: Cloudy with occasional light rain or snow showers in the north and a chance of light rain or snow showers central and south part. Saturday morning: Light snow showers ending in the north and becoming partly cloudy central and south. Saturday afternoon and evening: Becoming partly to mostly sunny. Saturday night: Fair with a few high clouds, mainly south part. * MT HOOD AREA- Friday afternoon and evening: Mostly cloudy with a chance of light rain or snow showers. Friday night: Cloudy with a chance of a few light rain or snow showers. Saturday: Becoming mostly sunny. Saturday afternoon and evening: Mostly sunny with gradually increasing high clouds. Saturday night: Becoming mostly cloudy with a chance of a little light rain or snow late. SNOW LEVELS-CASCADE MTNS 3500 ft N, 3000 ft C and S Friday aft and eve 3000 ft N and S Friday night 3000 ft N and S Saturday morning 3500 ft N, 4000 ft S Saturday afternoon and evening 4000 ft N, 3500 ft S Saturday night SNOW LEVELS-OLYMPIC MTNS 3500 ft Friday aft and eve 3000 ft Friday night 2500 ft Saturday 3500 ft Saturday 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 LT .10 LT .10 * MT BAKER LT .10 LT .10 * WASHINGTON PASS LT .10 LT .10 * STEVENS PASS LT .10 0 * SNOQUALMIE PASS LT .10 0 * MISSION RIDGE 0 0 * CRYSTAL MTN LT .10 0 * PARADISE LT .10 0 * WHITE PASS LT .10 0 * MT HOOD LT .10 LT .10 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS E 0-10 Friday aft and eve W 0-10 Friday night Var 0-10 Saturday morning E 0-10 Saturday aft and night * FREE WINDS AT 5000 FT S-SW 15-25 Friday aft and eve SW 5-15 Friday night and Saturday morning E 5-15 N and C, E 15-25 S Saturday aft and eve E-SE 10-20 Saturday night * FREE WINDS AT 9000 FT S-SW 15-25 Friday afternoon and evening SW 10-20 Friday night and Saturday morning S-SE 10-20 Saturday aft and eve SE 5-15 Saturday night EXTENDED WEATHER SYNOPSIS FOR SUNDAY THROUGH TUESDAY The Pacific Northwest should remain in the center of a large split in the Pacific westerlies Sunday. Towards the south, a low pressure system should move inland across northern California Sunday and spread a little moisture northward across the Mt Hood area and southern Washington Cascades causing a little light precipitation at times. Towards the north, a ridge of high pressure should extend into northern B.C. shunting Pacific moisture well north of the area. The upper ridge should gain strength over the Pacific Northwest Monday and Tuesday to allow for weak offshore flow, mainly fair skies and gradually rising freezing levels. EXTENDED FORECAST FOR SUNDAY THROUGH TUESDAY Sunday: Mostly cloudy south with a chance of light rain or snow showers. Partly cloudy north part. Monday and Tuesday: Becoming mostly fair with variable high clouds and gradually warmer. * SNOW LEVELS 2-3000 ft N, 35-4500 ft S Sunday * FREEZING LEVELS 5000 ft N and S Monday 5000 ft N, 8000 ft S early Tuesday 6-7000 ft N, 9-10,000 ft S late Tuesday