When will it finally rain? La Niña will trigger a season of heavy rains this summer in this country which needs water so much

In 2024, with La Niña, precipitation could be abundant in Mexico and tropical cyclones more numerous.
José Martin Cortés Meteored Mexico 05/13/2024 10:00 8 mins

All models simulating long-term conditions agree on the development of La Niña, a warmer Atlantic, lower wind shear and all of this combining for a more active hurricane season in the Atlantic and heavy rains in Mexico, we need to prepare!

La Niña is expected for the summer

The tropospheric circulation is gradually changing, which has already generated the first upwellings of water in the central-eastern equatorial Pacific, from the coast of Peru to the south of Mexico, leading to the weakening of El Niño, which will end in the coming weeks.

What if we could accurately forecast the climate using ECMWF’s Climate DT?

What if we could accurately forecast the climate using ECMWF's Climate DT?

In due course, we are already in a neutral phase with an anomaly close to 0°C, but the official monthly average is still above 0.5°C, meaning a weak El Niño is still in effect.

According to medium and long-term scenarios, at the end of May and the beginning of June, easterly winds over the Pacific will accelerate, causing the emergence of very cold deep waters, which will cause El Niño to collapse, transitioning to a brief neutral phase before officially reaching La Niña in June.

A warmer Atlantic and colder Pacific with La Niña would increase precipitation in Mexico.
A warmer Atlantic and colder Pacific with La Niña would increase precipitation in Mexico.

Global circulation will also be modified: the Pacific will cool, Atlantic winds will lose their intensity and precipitation will be more abundant in Central America, including Mexico. La Niña will be present throughout the summer and at least until spring 2025, with high intensity estimated.

Forecast for the coming months: heavy rain!

We could experience very radical changes, moving from this drought with a major water crisis due to weather conditions, but above all to overpopulation, which uses the vital liquid for its needs, to a situation of heavy rain with cyclones.

May: significant deficit due to El Niño

While this phenomenon dissipates, we will continue to experience a shortage of precipitation, due to the constant anticyclones that inhibit its formation, although eventually the troposphere has become unstable, supported by the relief and heat to generate violent storms, without this being enough to alleviate the drought.

Mowing your lawn during the month of May, a bad idea for biodiversity?

Mowing your lawn during the month of May, a bad idea for biodiversity?

However, during the second fortnight, the models show scenarios with the interaction of a cold front over the country and a possible first cyclone away from the Pacific coast, causing rainfall in the northeastern, central, eastern, southeastern and part of the western states. This phenomenon will be monitored.

June: start of changes

Tropical systems will strengthen in the tropical Atlantic and Caribbean, as well as in the Gulf of Tehuantepec, causing heavy precipitation (50-200 mm above normal) between Yucatan, Quintana Roo, Campeche, Chiapas, Tabasco, Oaxaca, Morelos, southern Veracruz and Puebla and eastern Guerrero.

In June, precipitation will increase significantly in the southeast and part of the center-east.
In June, precipitation will increase significantly in the southeast and part of the center-east.

A significant deficit is emerging in the west and along the Sierra Madre Occidental between Sonora, Chihuahua, Sinaloa, Durango, Nayarit, Jalisco, Colima, Michoacán and Guerrero with up to 200 mm below normal; between the Bajío, Valley of Mexico, north, northeast and east, the deficit may be lower with occasional precipitation.

July-September: time for action!

The models show an anomaly trajectory type, from the tropical Atlantic across the Caribbean and towards Mexico with heavy precipitation. In July, much of the country would have above normal precipitation with 25 to 150 mm, with the exception of Baja Californias, Sonora, Sinaloa and the coasts from Nayarit to Michoacán.

Floods, landslides or landslides, river overflows and dangerous watercourses will be very likely in this 2024 season.

August might be the rainiest month, as shown by almost all models, including ECMWF. Anomalies of 100 to 250 mm are likely in Coahuila, Nuevo Leon, Tamaulipas, Huasteca de San Luis Potosi, Hidalgo, Puebla, Veracruz, as well as southern Sinaloa in Chiapas.

Heavy rains are likely in August over much of the country; negative urban effects are possible.
Heavy rains are likely in August over much of the country; negative urban effects are possible.

From the Bajío to the Valley of Mexico, above-normal precipitation of 25 to 100 mm is forecast, although a deficit of 25 to 100 mm is expected in the northwestern states. The month of September is expected to continue with precipitation in states with positive anomaly, estimating 50 to 150 mm of additional precipitation.

Which systems will bring heavy precipitation?

The wind shear that prevents the formation of cloud systems or dissipates them would be very weak, which is common under La Niña, making the troposphere conducive to cloud formation. Additionally, the Atlantic Sea would be warmer, providing water vapor to generate clouds.

With La Niña and a warmer Atlantic, a large number of tropical cyclones could form and pose a threat to Mexico, in addition to heavy rainfall.

The circulation of the Azores High could play an important role in the hurricane season, extending towards Mexico, “delivering” these cyclones near or over the country. The Intertropical Convergence Zone, a rain belt located at the equator, would affect southern Mexico.

Recommendations or suggestions

It is important to have an emergency plan that allows you to know how to act in the event of extreme precipitation and/or a tropical cyclone, identifying evacuation routes, shelters, as well as home maintenance, having important documents at hand, among others.

Coastal tropical cyclones have intensified more rapidly in recent years

Coastal tropical cyclones have intensified more rapidly in recent years

We need to be aware of our surroundings: flood locations, proximity to a river, dangerous vegetation, saturated drainage, etc. All of this is important so as not to be caught off guard in the event of an emergency. Meteored will follow up on this issue.

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