Hurricanes in the toughest category are more common at this time of the year, but are usually not where Lorenzo is at the moment. This tropical storm with gusts of up to 260 km per hour is on its way to the Azores, an island group to the west of Portugal.
It is not so much the power, but the location and path of Lorenzo that make him very special. This situation is so unique that even at MeteoGroup they do not know exactly what to do with the second category 5 hurricane of the 2019 hurricane season in the Atlantic.
“Lorenzo can indeed be called a pretty special case,” says Britta van Gendt of the MeteoGroup in Wageningen. “It all went very fast, at first it all seemed not too bad, but he gained strength very quickly in recent days and is now of the toughest category. This is the most powerful hurricane ever observed at this latitude and he is approaching Europe. But how and what is guessing. Making predictions for the longer term is difficult because this situation is so unique. “
Unlike their American colleagues at the National Hurricane Center, European meteorologists do not have much experience with this type of immense weather system. “And the Americans don’t know exactly what he is going to do,” she notes.
TRADE WINDS AND EARTH ROTATION
Normally hurricanes occur above the warm ocean waters of the Atlantic Ocean off the west coast of Africa. Warm air from the Sahara and a sea water temperature of at least 27 degrees are the ideal conditions for such storm complexes. Through the Passat winds, a dominant powerful eastern current that flows between the Equator and 30 degrees north latitude, the vast majority of hurricanes then move to the American continent and the Caribbean.
However, Lorenzo is located north of that 30th parallel. Due to the rotation of the earth and gravity, the Passat wind moves north in the opposite direction. Because of this, he starts behaving differently and Europe comes into view. A situation that does not occur very often and certainly not in this severity.
STRANGE DUCK CALLED LORENZO
“It is a difficult thing to predict because there is little data from the past to base weather models on. Of course we have experienced the remains of other hurricanes in Europe, but this situation is different. According to our models, Lorenzo travels northeast along the Azores. On Tuesday or Wednesday, the inhabitants of the Portuguese archipelago will have to look for cover, how fierce it gets depends on the path. But it will certainly be quite windy and rainy, “said the meteorologist.
What happens next is uncertain according to Van Geldt. “Because of the trade winds, the path of Lorenzo will turn north-east towards the European mainland. Because he is so elusive, we do not know exactly what he will do next. Some models let him head towards France, while others say he is heading in the direction of Ireland or even Iceland. “
What does this mean for the weather in our country? “That depends on the path: if Lorenzo, who will then have been weakened to a depression, takes a northerly course then we will have to deal with turbulent autumn weather. If the remains of the complex go south of us, we can expect a dry and sunny weather type from the southeast. However, conditions in the Netherlands are not yet influenced by the hurricane. “
Due to the northern course, the wind speeds of Lorenzo are likely to decrease rapidly at the end of the week. Hurricanes need warm ocean water to maintain category 5 power and the water to the west of the Iberian Peninsula is too cool for this.
Hurricanes near Europe are relatively rare; “Ophelia in 2017, which at its peak belonged to category 3, comes closest. Due to the colder seawater, however, there was no talk of hurricane power. As a tropical storm, she landed on Ireland, so it was doing quite well, “she outlines. “However, these circumstances cannot be compared with hurricanes such as Dorian in the Bahamas last month or Irma in St. Maarten in 2017.”
Should we in the Netherlands be scared of tropical hurricanes of the toughest category? “No, they are not possible here,” assures Van Gendt. “The two ingredients are missing; Firstly, the seawater in our region is not nearly warm enough. And secondly, the British Isles ensure that hurricanes can never reach our country at full strength. The intensity of such a tropical depression is rapidly decreasing above land. If the supply direction comes from the southwest, the chance of a direct hit is also very small. The Channel between France and the United Kingdom is too narrow for a hurricane, an eye does not fit through it, so that the surrounding country still causes the wind speeds to fall considerably. “https://www.metronieuws.nl/in-het-nieuws/2019/09/categorie-5-orkaan-lorenzo-koerst-op-europa-af-hoe-uniek-is-dat