"We don't classify it as a tornado; the more specific definition has to do with the structure of the vortex column and its genesis. What I saw was a fire whirlwind," Paulo Narciso, from the Portuguese Institute of the Sea and Atmosphere (IPMA), explained to Lusa news agency.

According to the head of the Radar Meteorology Division, which studies tornado reports, this type of phenomenon, which lasts a very short amount of time, around 20 seconds, can occur more often than recorded.

"In forest fires, the conditions are enhanced by the fire itself for these types of fire whirls to occur, as there is overheating," said Paulo Narciso, adding that temperatures can rise "up to one thousand degrees."

He acknowledges that "differentiated temperature rises are created, causing strong upward currents, where there is a sudden change in wind."

In other words, "we see this type of phenomenon because we see the material being transported, the flames, the dust, the debris," said Paulo Narciso, adding that there may be more such phenomena, "but they can be difficult to detect because the fire is no longer burning."

"This was witnessed; it was visible at night because the contrast is evident, the updraft, with a small vortex," a column of air similar to a tornado, but not one, he explained.

According to the officer, the fact that it was recorded proves its existence, and the risk situation requires proximity to the fire for further study. Therefore, he acknowledges, "the danger is great, and the phenomenon's lifespan is short."

There are also videos on social media depicting a fire whirlwind phenomenon, also recorded in the fire that has been raging since Sunday afternoon in Sobral de São Miguel, in the municipality of Covilhã.

Paulo Narciso also reported that similar phenomena had already occurred during the large fires in Pedrógão Grande, in the Leiria district, in 2017.

According to the National Emergency and Civil Protection Authority website, the fire that started Friday afternoon in Alvite, Moimenta da Beira, was extinguished on Sunday night.