Winter is over us


AIS tracking Valid Voyage Weather forecast weather routing

During winter, the weather in the North Atlantic can be a challenge for all vessels.

Selecting the most optimal route is vital for securing the most cost-efficient voyage. Some of the most powerful storms on earth form in the North Atlantic Ocean during wintertime, spelling danger for crews unfortunate enough to encounter them.

The main reason for the heavy storms and the bad weather in the North Atlantic during the winter season is what is called North Atlantic Oscillation (NAO), which is a climate pattern that has a very strong influence over the North Atlantic. The NAO is a natural form of climate variability, explaining short and long phases in climate caused by natural, large scale features.

Other natural patterns of climate variability include the Northern Annular Mode, Pacific Decadal Oscillation, and the Atlantic Multidecadal Oscillation. The NAO forms a ongoing low pressure system, which exists over Greenland and Iceland, with a permanent high-pressure system existing over a group of islands roughly 750 nm west of Portugal, known as the Azores.

For most of the year, the high and the low pressures are mild, and their influence on the Atlantic basin climate is minimal. When winter enters, all of this begins to change. Both pressure systems grow much more intense and begin to vary from week to week between the two different states.

In one state, the positive NAO, the high-pressure system grows especially high. While the second state, a negative NAO, a low-pressure system grows especially low, creating a large pressure difference between the Azores and Iceland.

Photo: Geared container vessel sailing in challenging weather conditions.

The influence of the NAO and its phases can be felt across the entire Atlantic Ocean and the surrounding continents. Between the two circulating wind systems, clockwise and counterclockwise circulation patterns are created by the high- and low-pressure systems, there is an area where they come together and form a steady, forward moving wind that channels weather systems from the North America to Europe. In order to understand the NAO, it is important to understand what air pressure means.



Air-pressure is a measure of how much air is pushing down on the surface of the Earth at any given point. Normally, high and low pressure systems form when air mass and temperature differences between the surface of the Earth and the upper atmosphere produce vertical winds (more correctly vertical currents). In a low-pressure system, these vertical winds travel upwards and pull air away from the surface of the Earth, decreasing the air pressure above the ground or sea.

In contrast, in a high-pressure system, air is being pushed down. The higher in pressure a high-pressure system gets or the lower in pressure a low-pressure system gets, the more intense and larger the spinning circulation pattern becomes.

It is therefore highly suggested that a vessel Owner or Operator take contact to a routing company before commencement of a sea passage order for the routing company to plan the best possible route and avoid any danger both to the crew, vessel and cargo.

At Coach Solutions the route is planned basis the latest updated weather forecast, weather statistics for the last 10 years, vessels hull shape and the vessels current performance. By using the Coach algorithm, the most optimal route is planned and constantly monitored, avoiding bad weather, keeping the crew and cargo safe and at the same time optimizing basis fuel consumption, the value of time and minimizing the CO2 footprint.

The route will be recalculated multiple time a day taking the latest weather information and vessel position into account. This gives the owner or operator always up to date overviews of the estimated bunker consumption on a given voyage and a very accurate ETA for the vessels next port.

Example of weather routing from Voyage Optimization.


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