After El Niño, the La Niña phenomenon will arrive very soon! Towards altered atmospheric circulation?
The El Niño phenomenon is rapidly weakening, ending at the end of spring and giving way to La Niña from this summer of 2024. Will we go from drought to heavy rain?
The update of Thursday 14 March, 2024 of the Climate Prediction Center indicates that the El Niño phenomenon continues to weaken with a thermal anomaly of +1.4 °C in region 3.4, the cooling of the sea accelerating in the coming weeks with the passage of winds towards the East.
Intensity probabilities: La Niña is getting closer and closer
All dynamic and statistical models continue to be observed to weaken El Niño this spring, moving to a neutral phase between April and May with a potential of 83%, while La Niña is approaching or would officially begin in May or June.
It is very likely, more than 70%, that La Niña will be present during the second half of 2024, including in winter. It is difficult to determine its intensity, but current forecasts suggest it could have anomalies of -1.5°C or less, which corresponds to a strong to very strong La Niña.
This scenario should resemble what happened between 2007 and 2012, when we experienced a prolonged Niña, followed by a brief strong El Niño in 2010 and a return to a strong Niña, an event that triggered the worst drought in recent Mexican history.
In 1998, after a Super El Niño, a strong Niña quickly followed, a scenario that could be somewhat similar to this one in 2024.
What conditions will arise in the coming months?
As we have seen, the atmospheric circulation will evolve according to these phenomena, the influences of El Niño expected to persist this spring and until the summer and beyond, the effects of La Niña being felt.
Trend for April and May
Most models maintain a drier and warmer than thenormal scenario across most of the country, and this is very likely to remain true. However, other models emphasise wetter conditions in the northeastern and eastern states from Coahuila to Veracruz.
This could be associated with more active cold fronts producing thunderstorms, some being locally severe in turbulent conditions with the appearance of hail and tornadoes. Likewise, temperature drops can still be observed during strong northerly winds in the Gulf of Mexico.
Heat waves will become more and more likely, as is the case this season and even more so under El Niño. It is important to point out that it is IMPOSSIBLE to know if the heat will be record high or to know the dates and extent of heat waves.
Summer Scenario Update
To summarise, with La Niña, the tropical cyclone season in the Atlantic (including the Caribbean and Gulf of Mexico) is greater in number and, possibly, intensity, with the 2024 season being subject to a special attention due to warmer than normal seas, so it would not be surprising if an extreme situation occurs.
Above Mexico there would be a greater influence of the intertropical convergence zone, waves and the tropical cyclones themselves, whose trajectories are statistically directed towards our country. In the Pacific, the number of cyclones is lower, but not necessarily their intensity, which generates a very rainy season.
The southeastern, eastern, central, southern states and parts of the west and northeast could receive more rain this season. Over the northwest, the monsoon could eventually become more active with significant precipitation, but overall accumulations would be below normal.
Advantages and negative effects
It is well known that dams, lakes, lagoons, rivers and groundwater are drying up in various regions of Mexico. Arguably, the fastest way for these water masses to fill is under the impact of tropical cyclones, or also under rainstorms due to the interaction of the systems.
There is no doubt that no matter how much rainfall will reduce or end the drought, negative urban effects are very likely. In this context, it is important that the population is aware of the impacts on their locality and that they prepare for them by updating an emergency plan in good time.
If this scenario continues and depending on the needs, April and May would be a good time to take preventive measures.