Starting the news with a more comprehensive analysis of the climate, NOAA sees La Niña dissipating in March, entering a neutral phase. However, we mainly observe starting in April, a more defined climate pattern in the Southeast and Central West regions, without extreme drought or heavy rains. Still in this theory, there may be a decrease in rainfall in the north of the country, such as in the east of Amazonas, which will also be influenced by the movement of the ITCZ towards the northern hemisphere, that is, moving away from Brazil.
Evidently, the extreme north of Brazil, that is, Roraima and Amapá, will follow the opposite path, with large accumulations, influenced by the ITCZ in the equatorial region.
In the coming weeks, the Antarctic Oscillation in the positive phase will keep the weather stable for longer in the southern region of Brazil, as can be seen in graph 1, attached.
Graph 1 – Antarctic Oscillation (AAO)
Finally, for this week, the highest volumes of precipitation occur in the North of the country, the Center-West and mainly in the Southeast, which will have the highest accumulated rainfall of the week (behind Amapá and the extreme north of Pará), concentrating in the central-southern portion of Minas Gerais, Rio de Janeiro and Espírito Santo, as shown in image 1.
Image 1 – 7-day accumulated precipitation
In the North region, heavy rains occur due to the action of the ZCIT, with special attention to the north of Amazonas, especially the region of Maturacá and São Gabriel da Cachoeira, both in Amazonas, on the border with RR.
On Monday, the last cold spell that ed over the southeast is now at sea, near Espírito Santo, dissipating. However, the remnants of the frontal system still generate precipitation over Rio de Janeiro, which leaves the meteorological minimums below VMC at the airports of the capital of Rio de Janeiro in the morning, and generates convective precipitation over the region of Juiz de Fora, in Minas Gerais.
On Tuesday, a low pressure center appears at sea near Rio Grande do Sul, anchoring the humidity corridor coming from the Amazon, as seen in images 2 and 3, generating rainfall in Santa Catarina, Paraná, São Paulo and Mato Grosso do Sul.
Image 2 – Surface wind circulation, for 18/03.
Image 3 – Wind circulation at 10.000ft, for 18/03
On Wednesday, the low pressure center will become an extratropical cyclone, anchoring a new frontal system, with its main action in the Southeast, bringing large accumulations of rain from the north of São Paulo to the center of Minas Gerais, in addition to the coast of São Paulo and the entire state of Rio de Janeiro.
On Thursday, the cold front tends to park itself between the north of Rio de Janeiro and the south of Espírito Santo, increasing rainfall levels, especially in the capital Vitória. Also pay attention to the east of Minas Gerais, such as Barbacena.
Image 4 – Accumulated rainfall valid for 23:59 (UTC-3) on Thursday.
On Friday, the cold front begins to dissipate, but convective instabilities remain over Minas Gerais.
Following the opposite path, the entire Northeast region, with the exception of Paraíba to Maranhão, which still suffer from the ZCIT, has stable weather throughout the week, with little accumulation.
