MetSul Meteorology alert from Sunday And yesterday he reinforced his warning for a wave of thunderstorms with excessive rain and locally strong to severe thunderstorms with wind affecting Rio Grande do Sul in the second half of Tuesday and throughout Wednesday, with some models extending strong instability into early Thursday at North and in the northeastern Gaucho.
A very complex weather scenario with multiple weather systems in action will drive this period of elevated weather risk due to the wave of storms with the potential for significant damage and impacts on the population. The scenario involves two areas of low atmospheric pressure, an intense jet at low altitude with warm air and the meeting of colder air with a very warm air mass with the formation of a cold front (frontogenesis).
Understand. Low pressure in the middle and upper levels of the atmosphere (cold at low altitude) advances from the Chilean Andes and the Mendoza region of Argentina into central Argentina during this Tuesday. This low-level cold will hit Uruguay and parts of Rio Grande do Sul this Wednesday.
This type of system is most common to observe in the autumn months, when segregated low systems (cut-off lows) advance from west to east in South America, causing rain in the Atacama Desert and then thunderstorms with cyclonic formations in the center of the continent.
This system, however, will act in January, at the warmest time of the year and under abundant heated and unstable tropical air with strong to intense jets at low altitudes (between 1000 and 1500 m) within the continent which brings air that is too hot.
The strong wind currents, when they interact with the low cold temperatures at medium and high altitudes, end up significantly increasing the risk of strong phenomena with locally intense to heavy rainfall and thunderstorms which in some places can be very strong and destructive.
This low pressure is accompanied by colder air which, meeting the warm atmosphere, leads to the formation of very heavy clouds in Argentina, Uruguay and subsequently in Rio Grande do Sul, giving rise to waves of thunderstorms. If that’s not enough, a second low pressure, on the surface, will deepen in Northeast Argentina and advance towards Rio Grande do Sul this Wednesday, reinforcing the instability with heavy to heavy rain in several regions with the likelihood of new thunderstorms .
(1) An area of low pressure (cold) at middle and upper levels of the atmosphere advances from Chile towards western and central Argentina, heading towards Uruguay and southern Rio Grande do Sul before reaching the Atlantic with heavy rains and storms. (2) a second low pressure center advances from northeast Argentina to Rio Grande do Sul this Wednesday, reinforcing instability in the state with lots of rain and thunderstorms. (3) At the same time, an intense wind current will advance across Northern Argentina towards Uruguay and Rio Grande do Sul with very hot air that will provide energy to abruptly destabilize the atmosphere, generating intense and excessive rainfall with strong thunderstorms at high temperatures. wind and hail. | ART: JONATHAS COSTA/CORREIO DO POVO/METSUL
It is therefore not an ordinary and typical summer condition, in which the heat forms heavy clouds with isolated showers and thunderstorms. Instead, large-scale systems will operate in the state with a high potential for heavy to excessive precipitation and severe weather that will bring multiple risks.
The weather risk is high today and tomorrow with dangerous conditions across parts of the state, leading to a red alert being issued by official bodies in light of the spate of storms. Very high volumes of rainfall are expected in several areas with the risk of extreme precipitation accumulations. A large number of cities are expected to see between 100 and 200mm by Thursday, but there may be isolated signs of between 200 and 300mm.
The Central, Southern and Eastern parts of the state are expected to have the highest volumes, according to computer projections. Porto Alegre and the region are at high risk of excessive rainfall. To some extent, the scenario is similar to that of January 2010, even with El Niño, with heavy rains in the center of Rio Grande do Sul and the bridge disaster in Agudo. Conditions will be conducive to flash flooding, flooding, river overflows, stream overflows, landslides and barrier collapses.
Another risk is storms. Locally strong to severe thunderstorms could impact the state today and tomorrow. Today the risk is greater in the South, part of the West, part of the Center and part of the East. Tomorrow the risk applies to all regions. Hail may fall, but wind is the biggest threat with the potential for storm damage from gusts near and above 100 km/h, which can cause trees, poles, roofs to fall and leave large numbers of people in the Rio Grande do Sul without electricity.
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2024-01-16 14:29:10
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