The eye of tropical cyclone Belal arrived on Monday morning in Reunion Island, which is still on purple alert, which is expected to return to red. The prefect of the island, Jérôme Filippini, called on the population to remain confined in the face of the danger of this climatic phenomenon during which devastating winds are expected. But what exactly does the "eye of the storm" cover? And why should we be wary of it? Le Parisien takes stock of the situation.
The formation of a cyclone is always accompanied by an "eye", i.e. a gaping hole several tens of kilometres in diameter - usually 30 to 60 kilometres. In this area, the pressure remains very low and has higher temperatures aloft than those observed in the rest of the cyclone. It should be noted, however, that the eye is not necessarily in the center of the hurricane, but can move in various directions.
Due to lower pressure, the weather service may, in some cases, send a few teams by plane through this area to collect more detailed weather data on the cyclone. This information can be used to "disseminate early warning warnings to those in the path of the cyclone so that they can prepare," says the World Meteorological Organization (WMO).
Quiet weather... but misleading
Regarding cyclone Belal, Météo France has already warned: "With the passage of the eye of the cyclone over Reunion, the first phase of strong winds could be followed by a temporary lull, but this should not be interpreted as the end of the cyclone because the winds will resume very brutally in the opposite direction. "
For the first time in the eye of a storm. The transition (see below) is impressive. But you have to keep in mind that it's going to start up again in a few minutes. Already, this hour of respite does a lot of good... pic.twitter.com/yPD8FDtjcc
— Stéphane Bommert (@StephaneBommert) January 15, 2024
In concrete terms, the eye of a cyclone or hurricane remains the only area of the phenomenon marked by relatively low winds and little or no precipitation. Clear skies can even be observed. However, the eye of the storm remains particularly dangerous at sea: the winds surrounding this circular zone descend towards the surface of the water, forming waves that are often of great amplitude. Waves of 6 to 8 meters high were observed during the passage of the eye of Hurricane Irma in 2017.
Read alsoFollow our live coverage of Cyclone Belal in Reunion Island
The temporary lull should not be interpreted as the end of the cyclone. "We can say that's it, it's gone but in fact the elements will be unleashed again and the wind will start to blow brutally strong in the opposite direction once the eye has passed," says Sébastien Langlade, forecaster at Météo France with the Outremer channel La 1ère.
In the eye of the storm, alcamy is doing good before a recovery that will be very complicated to #belal #CycloneBelal pic.twitter.com/tu1RXLiwpI
— Jean-Sébastien (@JeanSbastien_G) January 15, 2024
The population still in lockdown
A common mistake during the passage of the eye of the cyclone is for people to go out to see the damage, thinking that the weather episode would be over. But the latter can be quickly surprised by the return of the "wall" on the other side of the cyclone, and its violent winds. Thus, despite milder weather, the authorities called on the population on Monday to remain confined, assuring that the cyclone would "create serious risks" throughout the day. In the same way, the rescue and security services can no longer circulate on the French island until further notice.
The only sign of relief is that "Belal is not expected to reach the stage of an intense tropical cyclone," the meteorological service said, comparing its impact to that of Cyclone Firinga in 1989. For the time being, the prefecture has confirmed a first death in Saint-Gilles, that of a homeless person who had not taken shelter. Reunion Island has not been hit by an intense cyclone for ten years and the passage of Bejisa in the first days of 2014.