Marine Weather and Tide Forecast for Herron Island, WA

SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
Rain is moving onshore over the Olympic Peninsula this evening as a weak frontal system will slide across the area into Monday morning.
No major forecast updates this evening. Previous discussion below:

High pressure remains in place across western Washington this afternoon, in the warm sector of an approaching frontal system.
Temperatures will continue a warming trend today, peaking in the 60s across much of the lowlands. However, this will be the warmest day of the period before a more active weather pattern settles into the region.

A splitting frontal system will enter the Pacific Northwest later today, spreading light showers inland over the Olympic Peninsula later this afternoon and further inland throughout the morning Monday. Showers may linger into the afternoon over higher terrain and along the Pacific Coast, and high resolution models continue to hint at post frontal convergence zone showers continuing over the northern Puget Sound into Monday evening. Precipitation amounts with this system will be light, with roughly a tenth or two of rainfall across the interior lowlands and up to an inch over higher terrain of the Olympics and Cascades. Temperatures Monday will also return back into the 50s for most areas, where they will stay for the rest of the week.

High pressure will rebound across western Washington into Tuesday, allowing conditions to briefly dry out. With light winds in place, patchy morning fog may form early Tuesday, but confidence is low. Tuesday will be a seasonable fall day with partly cloudy skies, some sun breaks, and high temperatures near normal. Chances for any rain on Tuesday will be confined to the Pacific Coast, with dry conditions inland.

LONG TERM /WEDNESDAY THROUGH SUNDAY/
A more active weather pattern will settle into western Washington Wednesday and beyond as a series of troughs pass over the Pacific Northwest.
Forecast models show good agreement over the general synoptic pattern, but continue to show some disagreement over the track of the low pressure system entering the region towards the latter half of the week. While some ensembles show the trough moving inland over Washington and Oregon oN Thursday and Friday, other ensembles show the low stalling southward along the California Coast before pushing inland over the weekend. While precipitation amounts remain uncertain at this time, confidence is high that western Washington will see continued wet and cloudy conditions Wednesday through the weekend. Near normal temperatures in the low 50s across the lowlands are expected throughout the long term.

15

AVIATION
A transition from exiting upper level ridge to entering shortwaves on the back side of this feature will gradually transition flow aloft from southwesterly overnight to more zonal by Monday morning. Surface winds largely southerly with variances to the southeast or southwest depending on location. Speeds generally 4-8 kts although PAE is seeing speeds up to around 10 kts this evening.

Widespread VFR conditions in place over W WA this evening although some isolated spots of MVFR to IFR are possible along the coast. As an approaching weakening shortwave approaches the area overnight, most terminals should see cigs lower down to MVFR to IFR by 10Z along with showers. While the lower cigs are expected to linger for much of the TAF period, perhaps meeting with some improvement to VFR in the mid to late afternoon, showers will be short lived as the system falls apart on its eastward journey. A stray shower here and there cannot be ruled out for the latter half of the TAF period, however confidence is simply not there to warrant any inclusion of such wording at this time.

KSEA...VFR conditions persisting this evening and into tonight before cigs lower down into MVFR range around 10Z early Monday.
Models remain in agreement that any improvement in cigs to VFR will likely hold off until the late afternoon...perhaps as late as around sunset. Winds will remain largely south to southwest and speeds remaining in the aforementioned 4-8 kt range. While still hinting at PSCZ development early Monday evening, this feature is expected to remain north of the terminal. A brief period of NE winds remains possible, but again, confidence is not there to warrant inclusion of this prospect in the TAF at this time.

18

MARINE
A weakening shortwave system will pass though the waters tonight. High pressure will rebuild in its wake Monday through Tuesday, before a more organized system moves through Wednesday and Thursday. A small craft advisory remains in effect through 12Z Monday for retreating gusty winds along the outer coastal waters through late tonight over 20 kt (as well as 10-12 ft seas). A push down the Strait of Juan de Fuca Monday night/Tuesday may bring breezy winds over 20 kt. The frontal system Wednesday/Thursday may also bring wind gusts over 20 kt to the coastal waters.

Seas Monday will decrease to 6 to 8 ft, and increase back to 9 to 12 ft Wednesday through Friday.

HPR/18

HYDROLOGY
A frontal system will bring light rainfall to western Washington later tonight into Monday morning, with the heaviest amounts up to an inch focused over the northwestern Olympic Peninsula and North Cascades. High pressure will provide a lull in rain before chances for heavier precipitation increase towards the end of the week. No flooding is expected over the next 7 days.

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SEW WATCHES/WARNINGS/ADVISORIES
WA...None.
PZ...Small Craft Advisory until 4 AM PST Monday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.