Instability increases significantly in the south of Brazil this Thursday with rain in the three states of the region and locally heavy rain in several locations. The unstable weather will be a consequence of a low pressure center that will also be responsible for a very windy holiday, particularly in the state of Rio Grande do Sul.
Rainy weather holiday in much of southern Brazil | GILSON ABREU/AEN
According to MetSul Meteorologia’s forecast, the All Souls’ Day holiday in Rio Grande do Sul will be marked by a lot of rain and strong wind. An area of deep low pressure acts over the state this Thursday before giving rise to a cyclone on the coast on Friday.
Many clouds cover the Gaucho territory with rain in all regions. Rain in several places will at times be moderate to heavy with a risk of isolated torrential showers. Localized wind storms and hail may occur.
What many people call the “All Souls’ Wind”, the wind from the East quadrant that usually blows at this time of year, more from the afternoon to the evening, will be strong to intense this All Souls’ Day 2023, especially in Rio Grande do Sul.
Much of the state will have gusts of 50 km/h to 80 km/h during this Thursday as an effect of the pressure contrast between the low pressure center over the continent, which will give rise to a cyclone tomorrow when it reaches the sea, and a high pressure of 1,025 hPa in the South Atlantic.
Instability on this farm also increases a lot in Santa Catarina and part of the state of Paraná. It rains in most of both states. Rain alone will be moderate to heavy with lightning and thunderstorms, with localized storms not being ruled out as the area of low atmospheric pressure deepens in southern Brazil.
See the maps below for the precipitation projection for the dawn, morning, afternoon and night of this Thursday based on the European Meteorological Center (ECMWF) model, which shows how instability increases greatly in southern Brazil throughout the holiday.
MetSul reinforces the warning of high potential for severe weather during the cyclone formation process, cyclogenesis. Storms are expected to hit the three southern states and also places in the Central-West and Southeast of Brazil between this Thursday and Friday.
The greatest instability will occur on Friday, when deep low pressure is over Rio Grande do Sul and migrates towards the ocean, intensifying and giving rise to the cyclone. On Friday, the risk of severe weather is very high in southern Brazil.
Heavy clouds will bring torrential rain, localized gales and hail during Friday in the three southern states. The worst of the instability on Friday will occur in the Northern Half of Rio Grande do Sul, Santa Catarina and Paraná. Some localized storms can be strong to severe with damage and the formation of tornadoes cannot be ruled out due to the sharp divergence of winds in the atmosphere.
The formation of a pre-frontal squall line associated with the cyclone in southern Brazil cannot be ruled out with strong to severe storms late Thursday and early Friday, which would worsen the potential for severe weather damage.
The cold front associated with the cyclone as it advances to the North is expected to stimulate isolated thunderstorms in isolated parts of many areas of the Central-West and Southeast of Brazil between Friday and Saturday. As the cyclone will be intense and will form further north than usual, close to Rio Grande do Sul, the front will be able to reach the Northeast of Brazil with rain and storms as far as Bahia.
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