Cape Shoalwater WA to Cape Lookout OR between 60 and 150 NM Offshore Forecast
| Today...Nw Winds 10 To 15 Kt, Becoming W 5 To 10 Kt. Seas 6 To 7 Ft. |
| Tonight...W Winds 5 To 10 Kt, Becoming Sw 10 To 15 Kt. Seas 5 To 6 Ft. |
| Fri...Sw Winds 15 To 20 Kt, Becoming S To Sw 20 To 30 Kt. Seas 5 To 8 Ft. |
| Fri Night...W To Sw Winds 15 To 25 Kt. Seas 6 To 9 Ft. |
| Sat...W Winds 15 To 20 Kt. Seas 7 To 9 Ft. |
| Sat Night...W Winds 15 To 20 Kt. Seas 8 To 10 Ft. |
| Sun...W Winds 10 To 20 Kt, Becoming W To Nw 10 To 15 Kt. Seas 9 To 10 Ft. |
| Sun Night...Nw Winds 10 To 15 Kt, Becoming N 10 To 20 Kt. Seas 8 To 9 Ft. |
| Mon...N To Nw Winds 15 To 25 Kt. Seas 8 To 11 Ft. |
| Mon Night...Nw Winds 15 To 25 Kt. Seas 9 To 11 Ft. |
| Area Forecast Discussion National Weather Service Portland OR 300am PDT Thu Mar 30 2023 Synopsis A strong front will move across the region bringing heavy rain and mountain snow across the area Friday through Sunday. A Winter Storm Watch is in effect. Cool, moist northwesterly flow will maintain snow accumulations in the high terrain into next week. Expect daytime highs to be 5-10 degrees below climatological normals. oday through Thursday...Current satellite and surface observations as of 2am shows midlevel ceilings starting to fill in. Weak undulations within moist, northwesterly flow will create an onshore push of marine stratus across the area by morning. This will keep temperatures above freezing across the lowlands as well as reduce widespread fog development. However, with the moisture in place and intermittent clearings will likely produce some patchy fog in some areas. Highs today will be on the cooler side as a very weak upper level disturbance over NW Washington, SW British Columbia looks to drag colder air aloft over SW Washington, NW Oregon this afternoon. This will keep daytime highs about 5 degrees below climatological normals. Winds will back to the southwest by Friday morning ahead of an approaching cold front out of the Gulf of Alaska. The westerly upslope flow across the Cascades will result in some light snow accumulations above 3500 ft during the overnight hours into Friday. The warm front will lift northeast Friday afternoon with a quickly approaching cold front expected to move onshore Friday night. South, southwesterly winds will ramp up across the area especially along the coast. Beaches and headlands could see wind gusts reach up to 50 kt Friday evening. The warm sector will bring enhanced Quantitative Precipitation Forecast and rising snow levels up to around 3000 ft Friday. Expect accumulating snow Friday morning with heavy snow expected Friday afternoon. High confidence (>80%) in 24 hour 12-15" snow accumulations starting Friday afternoon. The current Winter Storm Watch timing still seems reasonable so will not modify. A strong jet streak aloft will move overhead and to the south, putting NW Oregon, SW Washington on the north, ie cold side. The CWA will sit in the left exit region of the jet which is a favorable position for enhanced lift Saturday afternoon. This coupled with the cold air aloft driving instability a slight chance of thunderstorms are in the forecast for Saturday afternoon. Strong onshore flow in the postfrontal environment will maintain heavy cloud cover which will reduce the diurnally driven component of thunderstorm development. The upper level trough will eventually become a cutoff low by Sunday night as it moves south towards California. As it tracks overhead the snow levels around 2000 ft Saturday will drop to around 1500 ft Sunday. An attendant low level mesolow will drop south along the British Columbia coastline Saturday night into Sunday. This will promote enhanced onshore flow and moisture into the area. Again, high confidence (>80%) in 12-15" snow accumulations starting Saturday afternoon through Sunday afternoon. The current ending of the Winter Storm Watch when upgraded to a Warning may be extended in time. Cool, northwesterly flow will persist into midweek. Residual mountain snow showers will continue and daytime highs will remain 8-10 degrees below climatological normals. -BMuhlestein Marine Little change overall in the marine forecast. Benign conditions this morning will deteriorate Thursday night into Friday as a vigorous frontal system approaches the coast. This frontal system will move through the coastal waters Friday through Friday night, producing strong wind gusts. Gale force winds are likely Friday afternoon through Friday night, as NBM shows a 75-95% chance of gale force gusts. Will maintain the existing Gale Watch, but it appears likely the day shift will need to upgrade it to a Gale Warning. Leaned heavily on NWPS wave guidance, as much of the wave energy will be generated locally. This pushes seas up toward 13-15 ft along the northern and central OR coast. Winds are forecast to fall below gale levels by Saturday morning, though they will remain elevated through the weekend and into early next week. Long range models indicate active weather is expected to continue into next week due to multiple frontal systems moving through the Pacific NW waters. Weagle/HEC NOAA Portland OR Office: Watches - Warnings - Advisories OR...Winter Storm Watch from Friday afternoon through Sunday afternoon for Cascades in Lane County-Northern Oregon Cascades. WA...Winter Storm Watch from Friday afternoon through Sunday afternoon for South Washington Cascades. PZ...Gale Watch from Friday afternoon through late Friday night for Coastal waters from Cape Shoalwater WA to Florence OR out 60 NM. |
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