On Thursday, the prospect is that a stationary branch of the frontal system will limit the spread of the icy south air northward between Mato Grosso do Sul and São Paulo. This will occur at the same time as warm, moist northwest air flows along the front. The difference in temperature and the pattern of upper-level winds will reinforce upward movements and the occurrence of precipitation that can result in high accumulations, especially in the Paraná border region with the south and east of São Paulo.
During Friday, a powerful upper level disturbance gains energy and drives the jet stream northward between Brazil and the Atlantic, also supporting a high pressure system in Argentina and regions of low ocean pressure. This is a classic setup for cold air in the country. And in response, icy winds from the south push the cold front further north.
The peak of the cold wave will occur exactly over the weekend, where it is expected by widespread frosts in most of the states of Central-South Brazil. Some points in the Southern Region may have severe frost. To get an idea of ​​the cold, we are talking about temperatures close to zero degrees on Saturday morning in practically all of the Southern Region (except for coastal areas) and lower than 10 ° C throughout the State of São Paulo (except for the coastal zone ), much of Mato Grosso do Sul and southern Minas Gerais (including Minas Gerais triangle). Maximum temperatures do not rise in these places during the afternoon, although the sun shines in the sky. The southern portion of the Northern Region will also experience declining temperatures (chilly).
On Sunday morning, the pattern quoted above repeats itself. However, in the afternoon it is expected to dissipate the cold front on the continent, but the system will remain active in the ocean at the time of Salvador (Bahia).
With regard to snow in the coming days, tourists can be frustrated. In the last updates of the numerical predictions (GFS / ECMWF) there was a reduction in the availability of air humidity in the mountainous regions between the states of Rio Grande do Sul and Santa Catarina, which may limit the occurrence of winter precipitation in these locations. However, other models still maintain the snow (eg ICON and GEM).
Note: Information subject to updates.
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Meteorologist Bruno Capucin