To the measure that the Atlantic polar front walks for the equator the tropical instabilidades if dislocate for East or Southeast, announcing with tropical clouds and most of the time, rains, advent of the Atlantic polar front with anticipation of one day, will be able not to more reach the region. In accordance with Tubelis, on advent of the fronts in the Region, assures. The lines of tropical instability are associates with the undulation of the polar front. They form themselves in number of one or two, to the north of the polar front. They present orientation North-South highway and if they dislocate from west for east or Southeast, with speed of up to 60 km/h, being able to remain half-stationary. (TUBELIS, p.241). The Instabilidades Tropical that invades the Region Northeast, most of the time, if forms on Par and Gois.
From there, they dislocate themselves for East. Going for the south of the Region, repeated times, adentrando on the Bahia, and if losing on the ocean, simultaneously the air of the Atlantic retrocedes for the East. However, to the north, rare they reach to cross the State of the Piau, prevented for persistent high the tropical one on the interior of the Region, in the small latitudes. Another space repetidamente restrained to these inconstncias is in the eastern coast of the Northeast Region. In this place the Tropical lines of Instabilidades rare are consequences of transposies by means of the Maranho, constituted on of the proper coast. However, the presence of the depressions modified in the Northeast Region is lowered to written down in the interior of the Amaznia and the Regions the Center-West and Southeast. This drift consequently despite in the Summer, being the center of performance of the South Atlantic remaining alleviated and acuado for the East, on the ocean, and its inversion thermal she is very high, on the Northeast Region continuing in a raised back, adequately intense to block or to prevent the incursion of West of for insane chains.