The Australian Government’s Bureau of Meteorology’s Climate Service reported on its website on Tuesday, March 30, that most indicators related to ENSO (El Niനോo / Oscillano Zul) La Nina went from neutral to neutral.

In other words, the The La Nina phenomenon is over And the ocean Equatorial Pacific Returned to Neutrality.

The potential for climate models suggests that the Equatorial Pacific will survive Neutrality of ENOS until the end of winter.

ENOS or El Niനോo / South oscillation is a phenomenon of oceanic-atmospheric interaction with changes in oceanic and atmospheric conditions in the Equatorial Pacific region. When the temperature values ​​in the eastern equatorial Pacific show that the la nina condition is below average, that is, when we observe a negative anomaly of the SST (ocean surface temperature) and when there is a change in the air circulation associated with this pattern. “, Explains meteorologist Bianca Lobo.

The surface temperature of the ocean

As Ocean surface temperature The tropical Pacific Ocean remains neutral ENSO values ​​in recent weeks. Below the surface, most of the tropical Pacific is now approaching average temperature.

Atmospheric indicators

You are Atmospheric indicators, In general, indicates Neutral ENSO levels. The Southern Oscillation Index (SOI) is close to zero, while the trade wind strengthens the Madden-Julian Oscillation (MJO). Only the cloud near the equator shows a weak pattern similar to La Nina.

These changes are consistent with the analysis of climate models a Equatorial Pacific Return to Neutrality in the Autumn of the Southern Hemisphere Not expecting La Nina to return to normal in the coming months.

The return of neutral conditions in the Equatorial Pacific in the fall is also a model of the life cycle of ENSO events. Indicates all weather models ENSO will remain neutral until the end of the winter in the Southern Hemisphere.

Influence of MJO and AAO by the end of 2021

Without La Nina, with the neutrality of Equatorial Pacific, Other atmospheric indicators Start big Relevance to the analysis of variations in Weather In Brazil and South America in the fall.

Factors such as The Madden-Julian movement (Madden-Julian Oscillation, MJO) and South undo mode (To distinguish between Antarctic oscillation, AEO, AO, and Arctic oscillation) Helps to predict changes in rainfall and temperature over the next few weeks.

“Madden-Julian oscillations can be understood as clusters of convection clouds forming in the Indian Ocean near the Earth’s equator, which then travel around the world, increasing or decreasing rainfall over many continents. These changes occur at intervals of 30 to 60 days,” explains meteorologist Ana Clara Marquez. Climatempo.

O South undo mode (AAO) is currently neutral and is expected to remain neutral for the next fortnight.

“South Annual mode is basically the difference between the pressure level in the middle latitudes between 45 60 and 60 ഉയർന്ന and the high latitudes in the range between the latitudes between 60 90 and 90. If AAO is negative it means that more hurricanes and colder fronts are coming to Brazil than AAOA is positive. It is difficult for cold fronts to overtake Argentina and reach Brazil, ”explains Ana Clara Marquez.

Forecast for April

Starting in April Positive phase South Annual Mode above South America Cold fronts Continue on a more sea route, Without having a great influence on the inner continent.

“It simply came to our notice then The first 10 days are April We will observe the dominance of dry air mass in the central-southern part of Brazil. Therefore, most parts of the South, Southeast, and Midwest will have sunny days and dry weather. During this period, until April 10, rainfall over Brazil will concentrate in the northern region and the northeastern north coast, ”Ana Clara predicts.

After April 10, a Big change in rain pattern must occur in Brazil due to the influence of a Positive phase from MJO About the country.

“After April 10, the positive phase of the MJO begins to operate in Brazil, and we will see that Increased cloud cover and rainfall conditions In the Southeast, Midwest, and Northeast. Gois, Minas Gerais, Rio de Janeiro and Esperito Santo are the states that benefit the most from the rains. Some areas of Bahia and Sao Paulo, including Greater Sao Paulo, will experience increased rainfall. O Increased rainfall should be noted by the end of the first half of April. Ana Clara Marquez explains

Autumn chill

O April begins with the influence of a cold air mass Polar origin of heat dissipation in the southern states in the Midwest and Southeastern region.

As Capital Beginning of the month in Porto Alegre, Florianapolis, Curitiba, Campo Grande, Sao Paulo, Rio de Janeiro and Belo Horizonte Light mornings The lowest temperature ever recorded in 2021.

But this “new autumn” will not last for many days The heat will intensify over the Easter weekend. Those who enjoy the cold weather will have to wait until the end of April to experience the polar air again.

“The end of April will be marked by moderate to strong cold winds, but it will not have a major impact on the interior of Brazil. Temperatures are expected to fall sharply in the south, as well as in areas south and east of Sao Paulo, including Greater Sao Paulo,” said Ana Clara Marquez.