Portugal on alert as storms Bruna and Charles raise sting jet risk of 160 km/h winds

Portugal is on alert as the depressions Bruna and Charles pass over the country. For this Wednesday there is also the possibility of a phenomenon called sting jet, a rare meteorological event that can produce gusts with greater destructive power, as happened with Kristin at the beginning of the year, when it devastated several regions of the district of Leiria.The Greater Lisbon area deserves particular attention because this phenomenon may occur there, especially between midday and late afternoon on Wednesday.On Tuesday, during a precautionary press conference held by Civil Protection, IPMA acknowledged the possibility that a sting jet could form.

"There are some signs that it may occur, but it is very hard to predict. That is what happened in storm Kristin and it is on the table," said Jorge Ponte of IPMA.According to the Portuguese Institute for Sea and Atmosphere (IPMA), a sting jet is an air current that descends rapidly inside an extratropical depression and can hit the surface with great intensity. This phenomenon, which occurs in a relatively small and localised area, can produce very strong wind gusts, which may exceed 160 kilometres per hour, and cause significant damage.Climate change specialist Duarte Costa, who turned to social media to explain the phenomenon and warn of the associated risks, describes it as "an extremely violent jet of wind that drops from the mid-levels of a storm down to the surface, suddenly and in a very localised way, as a result of a strong intensification when passing through a jet stream".Simulations from the European ECMWF model show a hook-shaped pattern, "a dangerous similarity to the sting jet phenomenon", says Duarte Costa.The big difference compared with Kristin is that this time the storm will be most intense during daytime, that is, when more people are on the streets and roads, which worsens the situation.Duarte Costa warns that if the phenomenon coincides with rush hour, the period when travel is most intense, the risks could be heightened.Preventive measures in placeThe Portuguese government has declared a state of alert for this Wednesday across the entire mainland territory, in view of the approach of depression Charles.The Minister for Internal Administration, Luís Neves, announced the closure of all schools (public and private) and non-essential public services, a ban on movement in parks, forests and gardens, and urged the population to stay at home, warning that there may be "very difficult moments of need for rescue", with particular concern about urban flooding, falling trees and interruptions to the power supply.IPMA has placed eight districts under red warning: Beja, Évora, Faro, Leiria, Lisbon, Portalegre, Santarém and Setúbal, until 21:00 this Wednesday.All tunnels and parks in the city of Lisbon, as well as some bridges, will be closed from midnight.

The speed on the Vasco da Gama and 25 de Abril bridges, which connect the two banks of the river Tagus, has been limited to 60 km/h, and motorbike travel is discouraged.Lisbon Metro and Fertagus expect to maintain public transport services. However, the Carris bus operation may be adjusted during the day, depending on the severity of the bad weather and safety conditions.For its part, Rede Expressos has suspended services between 10:00 and midnight this Wednesday.