245 PM PST SAT JAN 05 2008 WEATHER SYNOPSIS FOR SATURDAY AND SUNDAY Slow down and listen, this aint no jive- Youve got to ratchet things back to stay alive. Shooting cracks on the slope, whomps on the ridge- Weve got no strong crusts to act as a bridge. The only crusts weve got are faceted and weak- And loaded by even more snow as we speak. Settlement is coming but not fast enough- And its hard to focus with all of that fluff. So whatever your sport, whatever your skill, Be avalanche aware or else you it will kill. Strong circulation around a very deep and strong upper low centered just west of the central Oregon coast continues to bring significant weather to much of the west coast, with its impact stretching from southern BC to southern California early Saturday afternoon. Although strongest westerly flow and heaviest precipitation continues across much of the Sierra Nevada Mountain into south-central California, a moderate to strong southwesterly flow over the Northwest brought a very strong surface and upper low northward Friday afternoon into early Saturday, and this circulation should continue to bring several more upper level disturbances over the region through much of the weekend. The most recent disturbance that brought very strong winds and slow cooling northward late Friday and Friday night is now gradually weakening over the central BC coast while increasing showers associated with the following moderate short wave trough moved northward over most areas Saturday morning. This was accompanied by continued strong but slightly decreased ridgetop winds and further lowering freezing levels. After this trough exits the region early Saturday afternoon, another upper disturbance is expected to bring enhanced showers onshore during the afternoon and evening hours before showers and winds gradually and briefly decrease later Saturday night and Sunday morning. Forecast models suggest that the last disturbance in the current series should move primarily into Oregon and north-central California late Sunday afternoon through early Monday. However, increasing circulation around this trough should still spread increasing light to occasionally moderate snow northward mid-late Sunday afternoon and night, with heaviest amounts likely in the Mt Hood area and southern Washington Cascades and lighter amounts further north. Fortunately only slightly increasing ridgetop winds are expected with this disturbance along with further lowering freezing levels. WEATHER FORECAST FOR SATURDAY AND SUNDAY * OLYMPICS- Moderate showers increasing Saturday afternoon and evening and becoming moderate to occasionally heavy. Moderate showers slowly decreasing Saturday night and becoming light showers Sunday morning. Light snow redeveloping and increasing Sunday afternoon and becoming light to moderate later Sunday afternoon and evening, heaviest south and southwest slopes. Light snow decreasing later Sunday night. * WASHINGTON CASCADES NEAR AND WEST OF THE CREST- * CASCADE PASSES, INCLUDING STEVENS, SNOQUALMIE AND WHITE PASSES- Moderate showers increasing mid-late Saturday afternoon and evening and becoming moderate to occasionally heavy. Moderate showers slowly decreasing Saturday night and early Sunday and becoming light showers Sunday morning. Light snow redeveloping mid-day and early Sunday afternoon south, spreading northward and slowly increasing mid-late Sunday afternoon and evening. Light to moderate snow south and light snow central and north Sunday night, decreasing early Monday. * EAST SLOPES WASHINGTON CASCADES- Light to occasionally moderate showers increasing Saturday afternoon and evening and becoming moderate, mainly higher terrain near the crest. Moderate showers decreasing Saturday night and becoming light showers Sunday morning with partial clearing. Light snow redeveloping early Sunday afternoon south, spreading northward later Sunday afternoon and evening, and becoming light to moderate south and light snow north and central. Light snow slowly decreasing late Sunday night north and early Monday south. * MT HOOD AREA- Moderate showers increasing Saturday afternoon and evening and becoming moderate to occasionally heavy. Moderate showers slowly decreasing Saturday night and early Sunday and becoming light showers Sunday morning. Light snow redeveloping mid-day and Sunday afternoon, slowly increasing later Sunday afternoon and evening. Light to moderate snow Sunday night, slowly decreasing early Monday. SNOW LEVELS-CASCADE MTNS 1500 ft N, 2000 ft S early Saturday afternoon 1000 ft N, 1500 ft S later Saturday afternoon 500 ft N, 1000 ft S Saturday night Sea level to 500 ft N, 500 ft S Sunday Sea level N, 500 ft S Sunday night SNOW LEVELS-OLYMPIC MTNS 1500 ft Saturday afternoon 1000 ft Saturday night 500 ft Sunday morning Sea level Sunday afternoon 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 SUN MON * HURRICANE RIDGE .5-.75 .25-.5 * MT BAKER .5-.75 .25 * WASHINGTON PASS .25 LT .25 * STEVENS PASS .25-.5 .25 * SNOQUALMIE PASS .25-.5 .25 * MISSION RIDGE LT .25 LT .25 * CRYSTAL MTN .5-.75 .25-.5 * PARADISE .5-.75 .25-.5 * WHITE PASS .25-.5 .25-.5 * MT HOOD .75 .25-.5 WINDS IN MILES PER HOUR (MPH) * CASCADE PASS LEVEL WINDS W 10-20 with higher gusts Saturday afternoon W 5-15 with occasional higher gusts Saturday night Variable 0-10 Sunday morning Variable mostly E 0-10 later Sunday morning and afternoon W 5-15 Sunday night * FREE WINDS AT 5000 FT SW 20-40 N and 20-40 Olympics, 15-20 S Saturday afternoon W-SW 15-30 Saturday night W-SW 15-25 Sunday morning S-SW 10-20 Cascades, 20-35 Olympics mid-day S 15-30 Sunday afternoon S 10-20 N, W 15-25 S Sunday night * FREE WINDS AT 9000 FT SW 25-40 Saturday afternoon SW 20-40 N, 15-30 S Saturday night W-SW 15-30 Sunday morning SW 15-25 Cascades, 20-40 Olympics mid-day S-SW 15-30 N, W-SW 20-40 S Sunday afternoon SW 15-25 N, W-SW 15-25 S Sunday night EXTENDED WEATHER SYNOPSIS FOR MONDAY THROUGH WEDNESDAY Following the last upper trough in the current series that should move to the east of the area early Monday, brief and very weak upper ridging should bring decreasing showers and some brief partial clearing later Monday morning and early afternoon. However, the next strong disturbance to affect the region should spread increasing clouds and light snow into the Olympics later Monday afternoon with further increasing light to moderate snow reaching the Cascades Sunday evening. Moderate to occasionally heavy snow should develop overnight into Tuesday morning, along with strong winds and a slight rise in freezing levels. However a strong easterly surface flow across the Cascade passes should help insulate these areas from the meager warming expected. Following the frontal passage mid-day or early Tuesday afternoon, the associated moderate to strong upper level trough should combine with significant instability showers to produce moderate to heavy orographic snowfall Tuesday afternoon, with a secondary and stronger trough further enhancing moderate to heavy snow showers late Tuesday into Wednesday morning when heavy accumulations are likely. This should also be accompanied by moderate to strong winds and low and lowering freezing levels. Weak to moderate upper ridging should move over the area on Wednesday to bring slowly and slightly decreasing showers. However, yet another moderate trough and associated frontal system should spread increasing light to moderate snow northward later Wednesday afternoon, becoming moderate to heavy Wednesday night, along with slowly and slightly rising freezing levels and moderate winds. EXTENDED FORECAST FOR MONDAY THROUGH WEDNESDAY Light snow or snow showers north and light to moderate snow south decreasing Monday morning with partial clearing mid- day and Monday afternoon. Light snow redeveloping late Monday afternoon Olympics, increasing and spreading into the Cascades Monday night. Moderate to heavy snow and windy later Monday night and Tuesday morning. Moderate to heavy snow or snow showers Tuesday afternoon through early Wednesday. Light to moderate showers Wednesday, increasing in the south and spreading northward later Wednesday afternoon and evening. Moderate to heavy snow redeveloping later Wednesday night. * SNOW LEVELS Sea level to 1000 ft N, 500 to 1500 ft S Monday 500 to 1500 ft N, 2-4000 ft S early-mid Tuesday 1-2000 ft N, 2-3000 ft S late Tuesday 500 to 1500 ft N, 1-3000 ft S Wednesday 500 to 1500 ft N, 2-4000 ft S late Wednesday, except snow levels lowering to the surface Cascade passes and east slopes later Monday, rising to near free air levels mid- day or early Tuesday afternoon