Welcome to the Weekly Weather Update – your guide to the world’s oceans and seas. Each week, we highlight key marine weather patterns and analyse unusual or significant weather events. From calm spells under high pressure to tropical cyclones forming in equatorial waters, and from jet streams steering oceanic storms to anomalies in sea-surface temperature that shape global climate patterns. Here’s what this week’s weather has in store.
A trough is currently moving south-eastward across the Netherlands. A ridge of high pressure is building over the UK and will move southeast across the North Sea on Wednesday. Pressure gradient is rather strong over the northern North Sea here, resulting in increase in winds up to 30-40 knots, especially along the southwestern Norwegian coast. Significant wave height is expected to increase up to 3.5 and even up to 4.5 meters in the northernmost areas.
From Thursday onward, a deep low-pressure system approaches from the Atlantic Ocean. This results in winds of 20-30 knots across the entire North Sea with waves varying between 1 meter in the south and 3-3.5 meters in the north. On Friday, the low passes the Faroe Islands and moves across the northern North Sea toward Norway. The southern side of the low will bring strong winds, particularly over the northern half of the North Sea, where a stormy south-westerly wind of about 35 knots and waves about 5-6 meters are expected. Farther south, the pressure gradient weakens, and therefore the winds are less strong. Due to the south-westerly wind, the UK provides shelter to the westernmost part of the North Sea, where winds are lowest at 15–25 knots and significant wave heights range from 1.5 to 2.5 meters.
On Saturday, a secondary low may develop near the English Channel, moving northeast, passing the Benelux on Sunday. The low is expected to dissipate shortly after, followed by a weak ridge.
A tropical disturbance with winds up to 30-35knots is currently located over the Philippines. The system will move across the South China Sea in the coming days and intensify significantly. The expectation is that the system will reach severe tropical storm (50-55 knots) status on Wednesday or Thursday and even may temporarily become typhoon. After that, the system will continue moving westward and is forecast to reach the east coast of Vietnam later on Friday or early Saturday. Here the winds may still reach 40-50 knots, bringing destruction to land. As the system moves further it will gradually weaken as it moves into an environment with increasing upper-level shear.
In addition, there is a tropical disturbance just south of Sri Lanka. The system will move northward along the east coast in the coming days while developing at the same time. Should the low-pressure system develop into a tropical storm, that would be quite unusual, as such storms are relatively rare around Sri Lanka. The last time a tropical storm struck Sri Lanka was Cyclone Burevi in December 2020. On average, about 20 tropical systems occur in the waters directly surrounding Sri Lanka per 100 years.
The strongest wind gusts are expected along the east coast, around Trincomalee. Local gusts may reach up to 100 km/h there on Thursday and Friday. However, the wind will not pose the greatest danger; the massive rain and thunderstorms swirling around the system will be the main threat to the island. The heaviest rainfall is expected in the mountains, where nearly 1200 mm of rain may fall by Friday evening. That is far more than what falls in the Netherlands in an entire year. Around Trincomalee, where more offshore operations take place, more than 800 mm of rain is also expected. The system tracks N towards India during the weekend.
Especially as the week progresses, conditions on the North Sea will become much more unsettled. At times, a near-gale northerly wind will generate high waves. Just east of the UK, the weather will still be somewhat better.
In addition, there are two tropical systems in Southeast Asia. The one near Sri Lanka is particularly notable because such systems are rare there, and locally up to 1200 mm of rain is expected to fall this week.
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