Marine Weather and Tide Forecast for Black Diamond, WA

SHORT TERM /TODAY THROUGH THURSDAY/
Upper level troughing will continue to remain the dominant influence over the region over the next few days as an upper level low spins across the northeastern Pacific. At the surface, a weak frontal system will approach the region today, bringing chances of showers mainly to the coast throughout the day. This system will then move inland overnight into Wednesday, bringing showers into the interior. Overall rainfall amounts with this system look to remain rather light, with most lowland locations likely only receiving a few hundredths to a tenth of an inch of rain. The bulk of the moisture remains focused in the mountains, where locally higher amounts up to a quarter of an inch of rain will be possible. High temperatures will be in the low to mid 70s across the interior today and in the low 60s along the coast. Afternoon highs across the interior will then cool a few degrees on Wednesday, topping out in the upper 60s to low 70s, while temperatures along the coast remain steady in the low 60s.

A few post-frontal showers will linger into Thursday, but generally expect Thursday to be a transitional, drier day across western Washington as a whole. Afternoon high temperatures will be similar to Wednesday, topping out in the upper 60s to low 70s across the interior and low 60s along the coast.

LONG TERM /FRIDAY THROUGH MONDAY/
The most notable precipitation of the week will arrive Friday into Saturday as the upper level low spinning across the northeastern Pacific sinks southward and pushes inland over the region. This system will bring more widespread rainfall to the lowlands, with most spots looking like they will receive anywhere from a quarter to half an inch of rain at this time. This cool system will allow for snow levels to fall between 5000-6000 feet over the weekend, bringing the potential for light snow accumulations to the tallest mountain peaks. Those with plans for outdoor recreation in the mountains over the weekend will want to make sure to monitor the forecast for the latest information. High temperatures will trend below normal as a result, generally in the upper 50s to mid 60s across the majority of the area.

Conditions start to warm and dry out again by Sunday with showers expected to gradually taper through the day and become more confined to the mountains by the evening hours. Some lingering shower activity may persist over the mountains on Monday, but expect the area to be drier overall as the low moves out of the region. High temperatures will warm a couple degrees each day, topping out in the mid to upper 70s across the interior by Monday afternoon and in the mid 60s along the coast.

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AVIATION
Southwest flow aloft continues today as an upper trough and associated weak frontal system approach Western Washington. The front will move onshore and dissipate early Wednesday. Areas of LIFR/IFR stratus extend inland through the Chehalis Gap into the Kitsap Peninsula. This will burn off toward 18Z. Increasing high and mid level clouds will continue through the day. Ceilings will fall back to MVFR along the coast by early evening with said conditions spreading to the interior terminals toward 09Z-12Z Wednesday morning.

KSEA...VFR to continue today under gradually increasing high and mid level clouds. Ceilings will deteriorate to MVFR overnight as a weak frontal system dissipates over the area. MVFR ceilings are expected Wednesday morning with isolated showers in the vicinity then ceilings are expected to lift back to VFR Wednesday afternoon.
Surface winds S/SW 6 to 9 knots. 27

MARINE
Surface high pressure will weaken today as a weak front approaches the area. The front will moves through the area waters Tuesday night into Wednesday. High pressure will briefly rebuild Wednesday and Thursday before a low pressure system slowly moves southward from BC Friday into Saturday. The overall pattern remains benign with no significant winds, expect in the Strait of Juan de Fuca, where diurnally driven pushes will continue each evening. The next strongest looks to be Wednesday night into Thursday which could require an additional advisory.

Seas remain 4 to 6 ft through Friday, bumping up to 6 to 8 ft early Saturday with the system moving through before going back to 4 to 6 ft next week.

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SEW WATCHES/WARNINGS/ADVISORIES
WA...None.
PZ...None.