Instituto de Meteorologia - Portugal
In Portugal research on tornadoes is very recent and has shown that they are not as rare as it is believed by public and even by scientific opinion. As tornadoes only affect a small area, the probability of their being observed at a meteorological station is very small. Thus most of the existing records are people’s recollections, some description in newspapers, and some photos.
It was possible to find data on 21 tornadoes that occurred since 1936 to 2000. This number is undoubtedly underestimated, because the database is always under construction. Those tornadoes were from moderate to strongly devastating, some of them causing great damage. The strongest tornado in Portugal, T7, happened on November 1954, causing 5 deathly casualties. The less intense tornadoes are, for sure, underestimated. During the year 2001, a more careful look for reports reveals the existence of some light tornadoes.
Tornadoes have been reported all over the country except on the Northeast mountainous area, but most of them were near the coast. There are 3 confirmed records of waterspouts moving inland.
Tornadoes occur mainly from October to January in severe cold fronts or line squalls. Most cases were in association with deep depressions west of Portugal, when there was a moist and warm southwest strong to gale-force flow and a generalised severe weather over the country. Some cases happened in a very unstable west flow.
There are also records on summer tornadoes, developing on strong thunderstorm cells. Those cells are mesoscale low pressure systems resulting from strong heating of the centre of the Iberian Peninsula.