IPMA confirms two tornadoes in Lisbon and Silves last week

The Portuguese Institute of the Sea and Atmosphere (IPMA) confirmed this Thursday two tornadoes over the Tagus River, in Lisbon and in the municipality of Silves, with damage confirmed in the south of the country.

In a statement, IPMA explained that on March 28, the southern edge of the Nelson Trench and associated frontal waves affected the mainland.

The Barlavento Algarve event was reported in the late afternoon of March 28 in Benaciata, parish of São Bartolomeu de Messina, municipality of Silves, in an incident that IPMA linked to a tornado after analyzing “radar observations, documentation and reports.” .

“This tornado destroyed two prefabricated homes, damaged other homes, and caused large trees to fall, damage vehicles, and telecommunications and electrical poles fall. The length and width of the destruction path of this event is unknown,” the institute said. statement.

The IPMA said that “preliminary analysis of the damage reported at the site indicates that the event reached at least F1/T2 intensity (classical Fujita scale/Torro scale),” stressing that the values ​​are still preliminary. .

Earlier, on the afternoon of March 28, a tornado was observed over the Tagus River.

“Based on analysis of the elements currently available, the tornado originated over the estuary waters, likely east of the Vasco da Gama Bridge, between 2:21 p.m. and 2:24 p.m.,” he added.

IPMA also noted that no known damage associated with the tornado allowed the institute to “assess its intensity.”

“In the central and southern regions, during the transition of the frontal swell from the northwest to the southeast, the necessary ingredients gathered for the formation of clouds with vertical development, sometimes with a supercellular (SC) nature. These disturbances are characterized by the presence of a mesocyclone. (MC), which corresponds to an organized rotational movement in the cloud, but is fixed only at altitude,” IPMA said.

“Only under very specific conditions is it possible for a tornado to form from the above-mentioned mesocyclone. A tornado implies, by definition, the presence of a vortex in contact with the surface,” he further emphasized.

Last week, a civil defense source told Lusa about the occurrence of two strong wind events following the passage of Storm Nelson through mainland Portugal, remembering that IPMA had to classify them as tornadoes or not.