This agroclimatological report has two objectives:
1.- Analyze the thermo-pluviometric behavior of Curicó between January and April.
2.- Estimate the probabilistic development of the warm El Niño event 2023.
Climatic period January-April.
Summer was characterized by excessive heat. The highest extreme maximum temperature per month was 34.7° C in January; 35.0° C in February; 33.0° C in March and 29.2° C in April. The warmest month was February, which averaged an extreme maximum monthly temperature of 32.3° C: it was 1.7° C higher than the climatic average for the month (30.6° C). March was also 1.1° C higher than normal: 29.8° C above the average of 28.7° C for the month.
Regarding heat waves, defined as when for three consecutive days or more, the maximum daily temperature is above a predefined value. For example, for January, 33° C. Each month has its own thermal limit value. Curicó recorded 38 days with heat waves from January 1 to April 30. By month, there was 1 in January; February 2; March 2 and April 1. In total, there were 6 heat waves.
As for precipitation, the first three months of the year recorded 0.0 millimeters of rain. This could be explained by the end of the cold La Niña event that occurred between February and March.
A cold frontal system, associated with an atmospheric river (defined as a cloud corridor with high potential for atmospheric humidity, which emerges from the tropics and connects with the frontal system), produced a precipitation event between Friday 28th and the early hours of Sunday 30th April.
In total, 35.2 millimeters of rain fell, accompanied by winds that at times had gusts of 40 to 50 kilometers per hour. However, Curicó continues with a deficit of 25.9%. The normal amount to date should be 47.5 millimeters of rain.
According to the statistical models analysed, the weather over the next 6 days (2 to 7 May) will be clear to partly cloudy: with a low probability of rain, but with a drop in minimum morning temperatures: values of 2 to 4° C above zero, associated with morning fog. Maximum temperatures would range between 15 to 18 or even 20° C.
The next El Niño event 2023.
Statistical and dynamic models estimate that a new warm El Niño event will occur in the central equatorial Pacific Ocean starting in June. This phenomenon is associated with rainy winters, storms and snowfall in the mountain range. At least this has been the case for the last 80 years.
The probability of this event occurring in winter is 70 to 80% according to the latest analysis in April. However, we must consider some background information.
1.- Curicó and the Maule Region have been affected by a mega drought that has lasted 16 years since 2007.
2.- During the mega drought there were three El Niño events: 2009-2010; 2015-2016 and 2018-2019. In red we can see that, contrary to what was expected, Curicó registered droughts. It seems that climate change is causing the potential for generating rainfall to be lost. For example, in 2002 there was an El Niño event and the year ended with a surplus of 67.1%, but since the beginning of the current mega drought (2007) there has been a negative change in the rainfall patterns associated with El Niño.
3.- According to ocean-atmospheric models, the El Niño 2023 event is likely to have its greatest impact on the rise in sea temperatures during spring, around 85%. If the next forecasts confirm this trend, there is a probability that rains may occur with warm environments during October-November. We know that this type of phenomenon, of heat and humidity, is usually harmful to fruit growing. Therefore, monitoring must be maintained regarding the evolution that El Niño 2023 would have towards winter-spring.
