Cape Shoalwater WA to Cape Lookout OR between 150 and 250 NM Offshore Forecast
| Today...Nw Winds 5 To 15 Kt, Becoming W 10 To 20 Kt. Seas 6 To 9 Ft. Scattered Showers. |
| Tonight...W To Sw Winds 10 To 20 Kt, Becoming S 15 To 25 Kt. Seas 5 To 8 Ft. Scattered Showers. |
| Mon...Se Winds 20 To 30 Kt, Becoming E. Seas 5 To 9 Ft. Scattered Showers. |
| Mon Night...E To Ne Winds 30 To 40 Kt. Seas 10 To 17 Ft. Scattered Showers. |
| Tue...N To Ne Winds 20 To 30 Kt. Seas 10 To 18 Ft. |
| Tue Night...N To Ne Winds 15 To 25 Kt. Seas 8 To 13 Ft. |
| Wed...N To Nw Winds 15 To 25 Kt. Seas 7 To 10 Ft. |
| Wed Night...Nw Winds 15 To 20 Kt. Seas 7 To 9 Ft. |
| Thu...Nw Winds 10 To 15 Kt, Becoming W To Nw 5 To 10 Kt. Seas 6 To 8 Ft. |
| Thu Night...W Winds 5 To 10 Kt, Becoming Sw 10 To 15 Kt. Seas 5 To 7 Ft. |
| Area Forecast Discussion National Weather Service Portland OR 315am PDT Sunday Mar 26 2023 Synopsis Showers will decrease today as high pressure builds in from the Pacific, but it will likely take until tonight to completely dry out. Deep low pressure is expected to rapidly develop 200-300 miles offshore of Brookings Monday, but the main impacts of this low expected to remain to our south. Light rain and mountain snow may reach as far north as NW Oregon Tuesday into Wednesday, then a return to progressive flow appears likely to bring another series of frontal systems through the Pac NW starting Friday or next Saturday. .SHORT TERM...Today through Tuesday...Satellite & radar show very little in the way of shower activity across the forecast area. However a vorticity center rotating into the central Washington coast will bring increased showers to the northern coastal zones this morning. Another disturbance slips into the north OR/south WA coast this afternoon and inland later in the afternoon. So should see increased shower activity. And with freezing levels low as they are some of the showers may produce small hail as the showers build into the hail growth region. Thunderstorms also possible inland late in the afternoon. And based on Quantitative Precipitation Forecast forecasts from hires models as well as Storm Prediction Center calibrated thunderstorm, southwest WA should see more shower/thunderstorm activity this afternoon. Temperatures remain below seasonal normals with expected highs around 45-50 degrees and snow level around 1000 ft this morning. But with only weak showers currently accumulating snow is unlikely at lowest elevations. Models continue to suggest impressive cyclogenesis will occur about 200-300 miles offshore of Brookings Monday. The 12z GFS (Global Forecast System) phases an upper low from the Gulf of Alaska with a subtropical system, with the resulting low strengthening from 999 mb to 982 mb between 10am and 10pm PDT Monday. A storm of this strength will pose concerns for multiple hazards, but most of these hazards appear to remain to our south. The 00Z EPS/GEFS ensemble members keep the low center south of Cape Blanco (and still well offshore) early Tuesday morning, so confidence is high that the primary wind and hydro impacts from this system will remain to our south. Models do suggest the low will push some wraparound moisture northward into NW Oregon and possibly SW Washington, but this moisture will have to contend with strong offshore flow on the north side of the low. Overall, Tuesday appears likely to be cool and breezy with some light rain as the low's occluded front pivots northward across the region. With 850 mb temps around 0 to -2 deg C, snow levels will likely be in the 3000-4000 ft range, but Quantitative Precipitation Forecast and snow amounts appear below advisory thresholds with this system for now. Weagle Long Term Wednesday through Saturday...The strong low pressure that develops off the S OR/N CA coast early in the week will become vertically stacked by Tuesday, causing the low to weaken. This system will push a strong cold front through California Tuesday, but the strongest moisture transport looks to remain south of the OR/CA border. Some wraparound moisture may keep some light precipitation over our forecast area into early Wed, but the overall trend will be for drier and somewhat more seasonable weather Wed/Thu. A more progressive flow pattern returns by next weekend, with the first in a series of fronts moving onshore into the Pac NW Fri night or Saturday for valley rain and mountain snow. /26 Weagle Marine Buoy observations from 3am PDT Sunday showed significant wave heigheights hovering between 8 to 10 ft across the coastal waters with a dominant wave period around 10 to 12 seconds. Winds were out of the northwest at 5 to 15 kt, however infrequent gusts around 20 to 25 kt were occurring with passing showers. Expect this trend to continue through Sunday while winds become more westerly and weaken slightly. Significant wave heigheights should also gradually decrease through the day as the ongoing northwesterly swell decays to around 6 ft in the late afternoon and evening. Winds will become easterly late Sunday night into Monday as offshore flow develops over the region. Easterly winds will then strengthen Monday night into Tuesday as a large low pressure system moves southward towards the northern CA coast. Models are now in good agreement with the track of this low. Expecting easterly winds to peak in strength Monday night at 20 to 30 kt, except for gusts to 35 kt around 50 to 60 nm offshore. Have issued a Small Craft Advisory for the inner and outer waters Monday afternoon into Tuesday to cover this threat, but feel gale force gusts over the far outer waters will be too limited in coverage to warrant a Gale Warning for the entire zone. The aforementioned low will also send a south-southwesterly fresh swell into the coastal waters, which is set to impact the waters Monday night through Tuesday when seas should peak between 8-13 ft, highest over the southern waters and lowest over the northern waters. Winds will weaken considerably Tuesday night into Wednesday as the low drifts further south down the CA coast and should turn back onshore by late Wednesday afternoon. Seas are expected to be below 10 ft during that time. -TK NOAA Portland OR Office: Watches - Warnings - Advisories OR...None. WA...None. PZ...Small Craft Advisory from 8pm Monday to 2pm PDT Tuesday for Coastal waters from Cape Shoalwater WA to Florence OR out 10 NM-Columbia River Bar. Small Craft Advisory until 6am PDT early this morning for Coastal waters from Cape Shoalwater WA to Florence OR out 60 NM. Small Craft Advisory from 2pm Monday to 5pm PDT Tuesday for Coastal waters from Cape Shoalwater WA to Florence OR from 10 to 60 NM. |
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