Marine Weather and Tide Forecast for SeaTac, WA

SHORT TERM /TONIGHT THROUGH SUNDAY/
The forecast remains largely on track this evening. Radar shows widespread light precipitation moving across the region tonight, with rainfall accumulations generally less than 0.10 inch expected. The previous discussion follows below, with some minor updates made to the aviation section. 14

Moist, westerly onshore flow continues on Friday for cloudy and cooler conditions. Forecast highs are only in the 50s or similar to today. Rainfall is mostly along the coast with isolated/scattered coverage inland.

The weekend weather is wet and unsettled as a trough and trailing upper low slide through. The air mass is slightly unstable on Saturday with a chance of afternoon/evening thunderstorms (mainly near the Cascades). Snow levels are low on Sunday, around 3500-4000 ft, and may see light snow in the mountains (inch or less). 33

LONG TERM /MONDAY THROUGH THURSDAY/
A ridge moves inland late Sunday and early Monday for a brief break in the weather.
Temperatures rebound slightly with highs in the lower 60s. A quick-moving front clips through western WA later Monday for more showers and windy conditions, especially along the coast. Onshore flow prevails moving forward, leading to cloudy conditions and near to slightly cooler than normal temperatures. 33

AVIATION
West to northwest flow aloft will continue as a weak upper trough and associated frontal system push across Western Washington. Ceilings will lower to MVFR in light rain at times this evening then persist across the region overnight into much of Friday as the system moves onshore.

KSEA...VFR ceilings will lower to primarily MVFR in scattered showers this evening. These conditions will then persist overnight and continue through much of Friday. Surface winds S/SW 7 to 10 knots.

27/McMillian

MARINE
A weak frontal system will approach the area then dissipate as it moves onshore on Friday. Surface ridging will rebuild offshore on Saturday then shift into the coastal waters early next week. This will lead to increasing onshore flow and likely headlines for the coastal waters and strait. Another frontal system looks to move through the area on Monday. Seas will generally remain under 10 feet through the forecast period. 27

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