Marine Weather and Tide Forecast for Seneca, OR

DISCUSSION
GOES-18 imagery shows an upper-level closed low churning offshore in the northeast Pacific. A well-defined cold frontal boundary is approaching the coast and forecast to move inland tonight into Sunday.

Ahead of the frontal passage, mild temperatures and breezy to locally windy south to southeast winds are ongoing and expected (80 percent confidence) into tonight. Windy conditions along the slopes of the northern Blue Mountains (east of Pendleton)
and through the Grande Ronde Valley are anticipated to persist due to a decently strong cross-Blues pressure gradient (~10 mb difference between Pendleton and Ontario).

Cold frontal passage tonight into Sunday will be accompanied by light precipitation and followed by cooler temperatures and breezy westerly to southwesterly winds.

Precipitation chances return Monday, especially late afternoon as a shortwave moves over the Pacific Northwest. Otherwise, cooler, near-normal temperatures are forecast.

Well-above-normal temperatures and periods of breezy to windy southerly to southeasterly winds are forecast again Tuesday through late week, with notable precipitation confined to the Washington Cascades and south-central Washington as ensemble guidance indicates an omega-block will develop (troughing over the East, ridging over the Plains and West, and troughing upstream in the Pacific). Under this pattern, precipitation is largely confined to the Cascades with drier conditions to the east.

Significant uncertainty in the 500-hPa pattern develops in ensemble solutions by late week into next weekend. Roughly half of ensemble solutions develop a closed low offshore in the Pacific and take it south of our forecast area into California or the Southwest, while the remainder show troughing extending from the Northeast Pacific into the Pacific Northwest. The former scenario would be warmer and drier while the latter scenario would be cooler and wetter across the region.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/
VFR will persist through the forecasted period for all sites.
Light showers this evening expected for KDLS/KPDT/KALW after 08Z for DLS, 13Z for PDT and 12Z for ALW. Winds will remain below 10 kts at all TAF sites except PDT/ALW which will see 11-13kts respectively. Lastly, high winds aloft will also contribute to 30kt shear at 2kft for KPDT/KALW/KPSC.

Preliminary Point Temps/PoPs
PDT 44 58 39 57 / 0 50 10 20 ALW 48 57 43 55 / 0 70 0 10 PSC 40 62 37 55 / 0 10 0 30 YKM 40 59 35 55 / 20 0 10 30 HRI 40 60 38 56 / 0 20 10 20 ELN 34 50 28 49 / 40 30 10 40 RDM 39 54 31 59 / 10 10 0 40 LGD 43 52 37 57 / 0 50 10 20 GCD 41 55 35 60 / 0 20 10 20 DLS 44 58 41 55 / 80 20 10 60

PDT WATCHES/WARNINGS/ADVISORIES
WA...None.
OR...Wind Advisory until 1 AM PST Sunday for ORZ507.