The analysis of the hourly rain frequency over Fortaleza City, located at Ceará State coast and in the north-northeastern Brazil, confirmed the well known higher rain incidence in the nocturnal period of the day, mainly during dawn until the early morning, throughout the year. The rain frequency analysis also showed a local reduction of the rains during the afternoon. The observation of meteorological satellite images, rainfall data and wind fields produced by numerical weather models have suggested, in this study, that the transit through the Fortaleza area (including its surroundings) of the western portion of the land-breeze front (system originated frequently between the eastern Ceara coast and the northern Rio Grande do Norte), may facilitate, through the convergence with the southeasterly winds, the occurrence of short duration, light rains mainly near dawn until the early morning. Moreover, the convergence of those breezes with large scale systems may also contribute to the high frequency of rains in the mentioned period. In this case, heavy precipitation can be generated. Otherwise, the sea-breeze observed in Ceara seems to cooperate to the lesser observed rain incidence in Fortaleza (under an area of cumulus suppression) during the afternoon period.
meso-scale meteorology; land-see breeze; rain; Ceara
