In the coming months, the equatorial Pacific could cool rapidly to start a new event of the cold phase of ENSO, a climate phenomenon known as La Niña. What is expected in Mexico?
The report issued by CLIMATE PREDICTION CENTER (CPC for its acronym in English) on July 8, notes that once again SURVEILLANCE returns likely the phenomenon of La Niña into this fall, based on the current trend of ocean conditions -atmospheric and its forecast. For now, we remain in a neutral phase as the anomalies persist near 0 ° C. Below the surface of the equatorial Pacific Sea, the water is becoming colder, a sign that La Niña is approaching.
The dynamic-statistical forecast assemblies indicate a probability greater than 60% for this cold phase to return sometime between September or October, persisting at least until next spring. Likewise, the intensity that it would present could be moderate on average, although we must wait for the phenomenon to consolidate in order to have a more accurate picture.
What effects can occur in Mexico?
Each ENSO event is unique and will depend on many factors to specifically determine the weather conditions that may occur. However, there is a statistic that does not help to know what could under this La Niña scenario: cyclone activity may increase in the Atlantic basin, decreasing in the Pacific, a situation that would generate increased rainfall over eastern and southeastern states. and parts of the center-south, while they are notably reduced in the north and west.
This generally occurs in late summer or autumn, when the interaction of tropical systems (wave and/or cyclones) with the first cold fronts can result in torrential rains over the mentioned regions. Towards winter, dry conditions will persist in the north and west, and Drought may develop; over the states of the Slope from Coahuila to Veracruz are probable incursions of arctic air with severe NORTES and very cold periods, interspersed with heat. On the Altiplano and mountainous portions, there can be days with dry cold and significant frosts.
What is La Niña?
On the surface waters of the equatorial Pacific Sea, temperature changes are monitored, from the coasts of Peru to the central portion of said ocean. Basically, when these waters cool down, it is called La Niña (otherwise, under warming it is called El Niño). Both phases involve changes in the circulation of the ocean and the atmosphere, but at a global level, La Niña favors a decrease in the average global temperature, as has occurred in recent months.
Statistically, this phenomenon can become more extensive in duration either by periods or by oneself and of less intensity compared to El Niño. The rain and temperature patterns in Mexico with the cold phase are on average: less hot and more rainy summers and extreme (hot-cold) and dry winters. We will be from Meteored updating all the changes that arise in this regard so that the population and sectors such as agriculture take the appropriate prevention measures.