December 2023 was marked by episodes of rain and impacts on agribusiness

The National Institute of Meteorology (Inmet) published today (10/01), a survey of the main meteorological phenomena that occurred in Brazil in December 2023.

The month was marked by episodes of rain that caused flooding, landslides and impacts on agribusiness. The rains that occurred in the states of Pará, Mato Grosso, Piauí and Rio Grande do Sul stand out, as the accumulated rainfall exceeded the historical average.

Still in December, in areas of the North, Central-West and Southeast regions, below-average rainfall was observed, due to the combination of the effects of the El Niño phenomenon and the warmer-than-normal Tropical Atlantic. The month was also marked by extreme heat.

Rain

In December, the largest rainfall accumulations (blue tones on the map in figure 1) were concentrated in the western part of the country, mainly in the northwest and south of Brazil due to the combination of heat and high humidity. 

In the South Region, in particular, the formation of low pressure and cold fronts were responsible for the occurrence of heavy rains, especially in the states of Rio Grande do Sul and Santa Catarina. While in part of the interior of the Northeast region, rainfall was below average.

In the North and Northeast Regions, the combination of High Level Cyclonic Vortices (VCAN) and heat and high humidity, cause rain showers in areas of Pará, Acre and Bahia. Highlight for Tarauacá (AC) with 129,0 mm, on the 7th; Itaituba (PA) with 147 mm, on the 18th and Ilhéus (BA) with 145,2 mm, on the 20th.

The formation of a humidity channel combined with hot and humid weather, increased instability in areas of the Central-West and Southeast Regions, causing accumulated rainfall in the municipalities of Padre Ricardo Remetter (MT) with 106,7 mm, on the 22nd; São Sebastião do Paraíso (MG) with 129,2 mm, on the 23rd and Paracatu (MG) with 133,4 mm, on the 24th.

Finally, the rain that occurred in the South Region is due to the combination of meteorological systems such as cold fronts and low pressure, together with the effects of the El Niño phenomenon. On the 4th, Passo Fundo (RS) accumulated 91,2 mm and Santiago (RS) reached 96,8 mm, on the 23rd. 

Figure 2a shows the satellite image from the 18th, at 18:40 pm (Brasília time), which highlights rain in a large part of the country, but especially in Itaituba (PA), which accumulated 147 mm. Furthermore, on the 20th, it was exceptionally rainy in areas of Bahia and Minas Gerais (figure 2b). It should be noted that areas in red indicate regions that are more favorable for the occurrence of intense rains.