1.- Agroclimatic scenarios for the month of May.
2.- Projections of the warm El Niño event and the beginning of La Niña.
The warm El Niño event continues its influence over the central-northern area of Chile. In the Maule region, the city of Curicó has accumulated, as of May 7, 72 millimeters of rain. The normal is 66.0 millimeters. Therefore, a surplus of 9.1% is reached. The frontal system on Tuesday, May 7, also left snow in the mountain range, with an isotherm of 800 to 1,000 meters high. All of the above is positive, since it is necessary for autumn to generate all the possibilities of rain and snow because the uncertainty about the eventual arrival of the La Niña event in the middle of the year would reduce the possibilities of intense precipitation and the corresponding snowfall during the second half of the year. Proof of the above is that during 2023, on the same date, it had rained only 35.2 millimeters. We must remember that until May of that year the cold La Niña event was present.
Dynamic and statistical models allow forecasting temperature and rainfall scenarios up to May 20. From the point of view of rainfall, after May 7, there should be no new precipitation. Thermal trends indicate a predominance of partially cloudy skies with maximum temperatures between 12 and 17° C and, importantly, the occurrence of morning frosts. Estimated values may range from 0° to -3° C below with a duration of 3 to 6 continuous hours.
It is recommended to take precautions against these events, which will become more recurrent as the cold event La Niña begins to generate its effects in the central zone of Chile: clear skies, fog, cold humidity and greater occurrences of radioactive frosts after each sporadic rain, or due to the greater presence of polar air masses in the central zone of Chile. All typical phenomena during winters influenced by the La Niña event.
Evolution of the La Niña phenomenon as of May 2024
According to the probabilistic model of the National Oceanic and Atmospheric Administration (NOAA) of the United States shown in the graph, sea surface temperature (SST) values would start to be negative from June onwards. From this month onwards, all statistical and dynamic models predict a cooling of the central equatorial Pacific Ocean (area 3.4) of up to 2° C below normal. This would become permanent from August to December (probably continuing into 2025). The month of June would be the month of transition to La Niña conditions, which would apparently be classified as “strong” on the intensity scale. Based on the above and in the current final stages of the current El Niño event, which contributes to generating rain and snow from cold frontal systems, intense but short-lived precipitation followed by frost should be expected in May and part of June.
Finally, one of the positive consequences that would accompany this phenomenon is the probability of accumulating a greater number of cold hours (base 7° C) between 1,000 and 1,600 hours between May and August. This would favor spring flowering without difficulties.
