Cold front to change weather with heavy rain and thunderstorms with gales

Cold front will advance through Southern Brazil at the beginning of this week with a high risk of locally heavy rain and isolated thunderstorms with wind and hail as it meets a warm air mass ahead of it, warns MetSul Meteorologia.
The Southern Region is currently under the influence of a warm, humid, and very unstable air mass causing very hot temperatures this Sunday with readings exceeding 35°C in Rio Grande do Sul and Paraná.
This warm and unstable air mass already caused isolated heavy rain and thunderstorms yesterday in the late afternoon and early evening in some areas from the Center to the Northeast of Rio Grande do Sul, but in the next hours, the atmosphere will be even hotter than on Saturday.
In the next few hours, the cold front will start to organize between the West and South of Rio Grande do Sul with rain that is expected to be locally heavy and accompanied by lightning, not ruling out isolated hail and localized gales. Even before the front arrives, the intense heat can trigger isolated instability in other regions of Rio Grande do Sul from the afternoon to the night of this Sunday due to intense heat with the highest temperatures in some cities since the end of summer and the beginning of autumn.
At the beginning of Monday, a not intense cold air mass begins to approach and enter the state of Rio Grande do Sul from Argentina and Uruguay, which will reinforce the front and make the system move North, bringing widespread rain to all regions of the state throughout the day.
The maps below, of precipitation and pressure, show the predicted movement of the cold front on Sunday night and in the early morning, morning, and afternoon of this Monday based on data from the European Meteorological Center (ECMWF) model.
As seen in the maps, the instability at the end of this Sunday will be greater in locations in the West and South of Rio Grande do Sul, although rain and thunderstorms will not be ruled out in other parts of the state that will be experiencing very high temperatures. The instability reaches its peak with the advance of the frontal system in the early morning and morning of this Monday. There is a possibility that the front will organize a line of thunderstorms that will bring locally heavy rain and thunderstorms, some of them isolated strong to severe, with hail and gales.
In the afternoon and evening of this Monday, the instability associated with the front will be more pronounced in the Northern Half of Rio Grande do Sul while in the West and South, the weather will gradually improve. Also on Monday, the system will destabilize the weather in various parts of Santa Catarina and in some areas of Paraná, such as in sectors of Western and Southern Paraná.