Cold front advances with heavy to intense rain, lightning and isolated thunderstorms | GABRIEL ZAPAROLLI
A cold front begins to enter the west and south of Rio Grande do Sul, causing locally heavy to intense rain and localized thunderstorms, some of strong intensity. The frontal system moves across the state throughout this Thursday, adding more disruptions and problems that will worsen an already dramatic situation in several communities in Rio Grande do Sul.
The cold front, as it advances through the state, will encounter very hot, humid and unstable air at altitude, which will favor the formation of clouds with great vertical development of storms, capable of generating abundant precipitation and storms of wind and hail.
MetSul warns that there will be episodes of heavy to torrential rain that will leave high or excessive accumulations in a short period of time, which will bring new flooding and worsen existing floods. The risk of landslides is high because the soil is already saturated.
In most locations, instability should be greater between dawn and morning. In the Northern Half, instability will remain strong throughout the day. Municipalities that have so far escaped excessive rain, such as the Northwest and several in Middle and Upper Uruguay, may have a lot of water.
The passage of the frontal system through Rio Grande do Sul will also bring a lot of lightning and thunderstorms with a high incidence of cloud-to-ground lightning in some places, affecting the electrical grid, since colder air will find the atmosphere quite heated at altitude.
Since a jet stream (wind) with hot air acts in the state, the risk of very isolated severe wind phenomena increases, such as tornadoes or atmospheric microexplosions when the front passes, but this is a different condition from the March event of widespread violent windstorms .
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The period of greatest risk for the passage of this cold front, therefore, will be between dawn and the morning of this Thursday. Over the course of the day, instability is more concentrated in the Northern Half while moving from the Center to the West and South of the state with the ingress of colder air. The day ends cold in the South and in the Campaign. See the evolution of the cold front on European model maps below.
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It is warned that the cold front reaches Santa Catarina, causing heavy rain and storms, especially in cities in the West and Midwest of Santa Catarina. The frontal system, then, should remain almost stationary over the North of Rio Grande do Sul and the state of Santa Catarina with excessive rain. The map below shows the five-day rainfall projection from the German Icon model as of today’s 9am startup.
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MetSul warns that rainfall can be very high to extreme in the north of the state, close to the border with Santa Catarina, and in several regions of Santa Catarina with river floods, flooding and floods. There will also be isolated storms, some of strong intensity.
The cold air in the front line will not be able to progress to break the atmospheric blockage of the warmer air that covers much of Brazil. The tendency is to bring smaller and milder brands only in Rio Grande do Sul. The Southeast of Brazil will continue to experience very intense and anomalous heat in May.
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