Rain and thunderstorms are about to return with greater intensity to mainland Portugal. According to the latest update of the European ECMWF model analysed by Meteored, it will be from 3:00 PM on Saturday, September 5th that thunderstorms should intensify in the North and Centre of the country, with the period between 3:00 PM and 6:00 PM emerging as the one in which electrical activity could be most pronounced. Rain should become more significant from 5:00 PM onwards, especially in the interior of the North and Centre, which may be accompanied by sometimes intense thunderstorms.
The most consistent signal of instability is concentrated in the North and Centre of mainland Portugal, especially in the interior. Projections indicate greater thunderstorm potential in areas of these two regions, with some nuclei possibly becoming locally intense during the afternoon. Meteored even points to cells capable of producing moderate to heavy precipitation over short periods, with accumulations locally close to 8 millimetres in one hour and densities exceeding 15 lightning strikes per square kilometre, with also a localised possibility of hail and strong gusts.
The arrival of instability does not mean the immediate end of the heat. IPMA maintains 14 districts of mainland Portugal under yellow warning for hot weather, with only Aveiro, Braga, Porto and Viana do Castelo outside that warning. Maximum temperatures could range from approximately 27°C in Viana do Castelo and Aveiro to 38°C in Évora and Beja. It is precisely the contrast between strong heating near the surface and relatively colder air at altitude that will help create conditions for the development of convective cells.
The instability should be relatively short-lived, with Sunday, September 6th, bringing a significant improvement and the return of more stable conditions across most of the territory. Temperatures should also begin to drop, especially on the North and Central coast, with maximum temperatures close to 21°C in Viana do Castelo, while in the southern interior the heat may continue intense, with Évora and Beja possibly reaching 37°C.
