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.
This week, autumn continues to deliver its best, bringing low-pressure areas and associated unsettled conditions to the North Sea. The chance for wintry conditions also increases this week as cold air is transported southwards from the arctic regions.
Low pressure lingers over Scandinavia today and tomorrow, declining on Thursday. At the same time, high pressure is present over Greenland, Iceland and the northern Atlantic. This set-up results in a firm northerly flow, bringing colder air towards the North Sea. This colder air induces lots of (wintry) showers. A secondary low pressure area moves southeast over the UK today and is expected to arrive over The Netherlands tomorrow. This low interrupts the northerly flow a bit, with winds and waves slightly dropping until tonight. While crossing the southern North Sea, low pressure results in a low confidence situation for parts of the Humber and Thames shipping sectors. On the southern flank of this low winds continue to be fresh or strong. On the western flank, the firm northerly flow restores from early tomorrow onwards. Winds are expected to become strong to near gale (22 – 30 kts) over the western North Sea and west of the Benelux. Highest winds speeds may occur in the Dover area, due to a local funnelling effect.
A small-scale low pressure core is expected to move south across the North Sea later tomorrow and Thursday, reaching France in the night to Friday. This results in further enhanced winds along the UK east coast, possibly reaching gale force (34 knots). The significant wave height reaches up to around 3.0 meter west of the Benelux and 3.0 – 5.0 meter over the western North Sea later on Wednesday and Thursday (with the highest waves in the north over parts of Fair Isle and Viking in the night to Thursday). On Thursday, low pressure is expected to cross the Baltic Sea before declining over the Baltic countries on Friday.
High pressure is expected to move southwards on Wednesday, settling over the Azores island on Thursday. An associated ridge extends over the North Sea early Friday, but is forecasted to move quickly east afterwards. Winds will temporarily drop to calm or moderate (5 – 15 knots) and waves will drop to 2.0 meters or below on Friday. New Atlantic low pressure will likely reach the North Sea again during the weekend. The associated westerly to southerly winds will push the colder air northeast again. Winds and waves increase again from late Friday onwards, likely reaching (near) gale force again on Saturday. However, the confidence is low for this time period. The various weather models are not yet in agreement on the exact positioning of low pressure and its associated frontal troughs.
When the Northern Hemisphere tropical cyclone season gradually comes to an end, things start to heat up over the Southern Hemisphere. The Australian cyclone season officially runs from 1 November till the end of April and is now seeing its first serious activity over the Timor Sea. It has already resulted in extreme rainfall amounts in the northern part of Northern Territory. A total of 228 mm of rain was registered on Charles Point near Darwin in just 24 hours, its heaviest rain event in a decade.
Tropical low 02U (named by the Bureau of Meteorology; BOM) currently lingers over the Timor Sea just northwest of Darwin and may develop into Australia’s first tropical cyclone of the season later this week, called “Fina”. The environmental factors are favourable for cyclone development, which is why the BOM in Australia indicates a high risk of cyclone development from Wednesday onwards. The system remains slow moving in an easterly direction over the Timor Sea the coming days, while gradually strengthening. It is then expected to take a turn to the south then southwest towards the northern coast of Northern Territory on Thursday and Friday. When making landfall by the end of this week or early next week, it will be added to a very short list of November landfalls in Australia. In Australia’s cyclone history, only 4 cyclones have made landfall in November. The latest one was tropical cyclone Alessia in 2013 and before that severe tropical cyclone Ines in 1983. The 30-year gap between these two cyclones underscores just how infrequent these events are in November.
When performing marine operations in this area in the coming period, please regularly consult the provided weather forecasts and please follow the warnings from official local institutions. It is important to act proactively during these events to minimize the risk for damage or loss of life.
Unsettled conditions continue as several low-pressure areas are expected to affect the North Sea. Combined with the colder arctic air this will induce wintry conditions from time to time. By the end of the period, milder air is expected over Northwest Europe as Atlantic low pressure comes in from the west again. Stable and calm high pressure influence is not yet expected over the North Sea in the near future.
The Australian cyclone season kick off with a possible tropical cyclone developing over the Timor Sea and may even result in a rare November landfall event over Northern Territory or the northeastern part of Western Australia.
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