Cape Shoalwater WA to Cape Lookout OR between 150 and 250 NM Offshore Forecast
| Today...Nw Winds 20 To 25 Kt. Seas 7 To 11 Ft. Chance Of Rain. |
| Tonight...Nw Winds 15 To 25 Kt. Seas 8 To 10 Ft. |
| Sun...Nw Winds 10 To 15 Kt, Diminishing To 5 To 10 Kt. Seas 6 To 8 Ft. |
| Sun Night...Nw Winds 5 To 10 Kt. Seas 5 To 6 Ft. |
| Mon...W Winds 5 To 10 Kt, Becoming Variable. Seas 4 To 5 Ft. |
| Mon Night...W To Nw Winds 5 To 10 Kt, Becoming Nw 5 To 15 Kt. Seas 4 To 6 Ft. |
| Tue...W To Nw Winds 5 To 15 Kt, Becoming W 5 To 10 Kt. Seas 4 To 6 Ft. |
| Tue Night...W Winds 5 To 15 Kt. Seas 4 To 6 Ft. |
| Wed...W Winds 5 To 15 Kt. Seas 4 To 5 Ft. |
| Wed Night...Nw Winds 10 To 15 Kt, Becoming W To Nw 5 To 10 Kt. Seas 4 To 5 Ft. |
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Area Forecast Discussion ...UPDATED National Weather Service Portland OR 954am PDT Sat Jun 21 2025 Updated Aviation Discussion... Synopsis A low pressure system will bring widespread rain today with a 10-20% chance for thunderstorms. Any thunderstorms that develop could produce lightning, heavy downpours, and gusty outflow winds. Drier and warmer conditions return Sunday into early next week. Slight chances for precipitation return Wednesday to Thursday. .SHORT TERM...Now through Monday Night...Radar imagery as of early Saturday morning depicts scattered showers across northwest Oregon and southwest Washington as an upper level low moves directly overhead. Later this morning, another surface shortwave associated with the upper low will swing through the area and bring another round of rain. This time, it appears the rain will be mostly stratiform in nature rather than showery and convective like yesterday. High-resolution guidance shows the rain progressing south-southeastward from the north-northwest, beginning along the north Oregon and south Washington coasts around 5-7am and spreading further inland by 8-10 AM. Afternoon highs remain well-below normal today for interior lowland valleys, peaking in the upper 50s. Thunderstorm chances today are around 10-20%, highest along the coast and Lane County where more instability will be present. HREF guidance suggests SBCAPE values around 100-150 J/kg today for these locations. Elsewhere, the thunderstorm threat is more minimal as the entire atmospheric profile cools down and the cloud layer deepens. Any thunderstorms that develop today could produce lightning, heavy downpours, and gusty outflow winds. Not as confident with small hail since model soundings suggest the instability fails to tap into the -10 to -30 deg C hail growth zone. Remember - when thunder roars, go indoors! The current 24-hour rainfall forecast from 5am Saturday to 5 AM Sunday calls for 0.75-1.50" along the coast and Coast Range, 0.50-0.80" across the Willamette Valley and southwest Washington lowlands, and 0.60-1.50" across the Cascades and foothills. Can't rule out the possibility for higher amounts across the Willamette Valley and southwest Washington lowlands, where NBM guidance suggests a 15-20% chance of receiving 1" or more of rain. Although it's a low chance, this scenario could occur if instability ends up being greater than forecast. HREF currently shows precipitable water values around 1" today west of the Cascades, so if there's enough convection, all the moisture in a given atmospheric column could precipitate out and lead to higher rainfall amounts. Expect some lingering showers and stratus clouds Sunday morning as the system exits the region. Conditions will gradually dry out and become more sunny by the afternoon. Onshore flow continues, but winds are forecast to shift more northwesterly as surface high pressure re-builds. Temperatures on Sunday will begin to rebound into the low 70s for interior lowland valleys. High pressure continues to build on Monday, leading to mostly sunny conditions and temperatures further warming inland into the low 80s. -Alviz Long Term Tuesday through Friday...On Tuesday, most ensemble members and deterministic guidance suggest a shortwave trough passing through the Pacific Northwest. It's a very weak disturbance with no precipitation expected. 500 mb heigheights still remain near or above normal during this time, so still expecting temperatures to remain warm. However, at the same time guidance suggests westerly winds will increase as onshore pressure gradients tighten. While temperatures remain forecast in the low to mid 80s on Tuesday, these temps have come down compared to previous runs which originally had inland temps peaking in the upper 80s. This would make sense with increased onshore flow. Wednesday to Thursday, about half of the global ensemble members suggests 500 mb heigheights fall slightly due to additional troughing dropping into the Pacific Northwest. The other half of ensemble members maintain more zonal flow with above normal 500 mb heights. If we were to end up with more troughing, this would be accompanied by increased cloud cover and return of chances for light precipitation. But if we maintain more zonal flow, we could end up staying warmer and drier. The current forecast has temperatures falling into the 70s Wednesday to Thursday with 15-30% chance for rain, mainly along the coast, high terrain, and southwest Washington. This slight downward trend in temperatures and low chance for precipitation makes sense for now given the uncertainty of the pattern. By Friday, 75% of ensemble members suggest zonal flow or ridging, which would return drier and warmer weather. -Alviz Marine An anomalous upper-level trough will continue to progress through the region today producing unsettled conditions. Winds remain west to northwest 5-15 kts, then increase to 10-20 kts with gusts to 20-30 kts as the surface front moves through the waters early this morning through this evening. Current guidance projects a 70-90% chance for Small Craft Advisory winds for the waters 20-60 nm west of the coast and 40-60% for the inner waters. Seas around 5-7 ft increase to 6-9 ft with the frontal system at 9-10 seconds. A Small Craft Advisory remains in effect for the outer waters for 5am today through 5am Sunday. Additionally, a Small Craft Advisory has been issued for the inner waters for 5am through 9pm today for combined Small Craft winds and seas. Winds and seas decrease on Sunday as high pressure begins building over the eastern Pacific. Expect winds 5-10 kts and seas 4-6 ft by Sunday morning, continuing into Monday. These generally quieter conditions are expected to persist into the midweek. -HEC/Schuldt NOAA Portland OR Office: Watches - Warnings - Advisories OR...None. WA...None. PZ...Small Craft Advisory until 9pm PDT this evening for PZZ251>253. Small Craft Advisory until 5am PDT Sunday for PZZ271>273. |
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