El Niño and October rains: which areas of Argentina could exceed usual values

The European model anticipates rainfall above usual values in northeastern and western Argentina during October (Illustrative Image Infobae)The influence of El Niño appears as one of the factors that may influence the rainfall pattern forecast for October: rains above usual values are expected in productive areas of northern and western Argentina. The latest monthly projection from the European Centre for Medium-Range Weather Forecasts (ECMWF) anticipates a wetter pattern for large areas of Argentina, Paraguay, Uruguay and southern Brazil. The trend does not define what will happen each day nor does it anticipate precise accumulations by city, but it allows observing which regions have a higher probability of receiving rainfall above or below their usual levels during the month. According to meteorologist Leonardo De Benedictis, of Meteored, the new scenario "consolidates the wet pattern for much of the country." The projection places the greatest positive precipitation deviations over northeastern and areas of western Argentina, while southern Patagonia and sectors near the Andes mountain range show a different signal. The ECMWF monthly projection shows a wet signal that also covers Paraguay, Uruguay and southern Brazil (Illustrative Image Infobae)The ECMWF monthly forecast indicates that northeastern Argentina appears among the areas with the greatest chances of receiving rains above the historical October average. The west of the country also shows a trend favorable to more frequent or abundant precipitation compared to usual climate values. This is a positive precipitation anomaly. In simple terms, the model estimates that the total amount of rain for the month may be above the average calculated for that time of year in each region. It does not imply that it will rain every day or that there will be constant storms, but rather that the monthly balance would have more humidity than usual. The signal is not limited to Argentine borders. The model's maps show a continuity toward Paraguay, Uruguay and southern Brazil, with a rainfall configuration covering much of the region. That geographic extension makes it possible to identify a regional atmospheric behavior and not an isolated phenomenon over Argentine territory. Northeastern Argentina concentrates the highest probabilities of recording precipitation above the historical October average EFE/ Pedro Puente Hoyos The report does not establish a single cause for this behavior, although it places October as a period of seasonal transition. During this month, the systems that dominated winter lose influence and patterns typical of the warm months begin to gain ground. That transition modifies the circulation of moisture and the distribution of precipitation. Therefore, the north, center and south of the country may exhibit different responses within the same month. De Benedictis explained that monthly projections make it possible to identify "the bias or deviation of the period," based on the comparison between expected conditions and climatological values. In other words, they show a general trend for October, without describing what will happen day by day. The model also projects positive rainfall anomalies in part of the center and north of Patagonia. The signal, in any case, appears less uniform than in northeastern and western Argentina. The monthly forecast does not anticipate daily storms, but rather a trend of greater humidity in the October balance (Illustrative Image Infobae)This means there could be relevant differences between provinces, localities and even weeks. One sector of the region may record rains above the average, while another may remain close to normal values. For activities that depend on the weather, such as agricultural production, this information serves as a context indicator. However, it is not enough to define specific tasks, since those decisions require shorter-term forecasts and data observed in each area. Toward southern Patagonia, the signal of rains above the averages loses strength. In sectors close to the Andes, the scenario forecast by the ECMWF even points to monthly precipitation below usual levels. A negative precipitation anomaly does not mean a total absence of rain. It indicates that, at the end of the month, the estimated accumulation could be lower than the historical October average for that region. The data also does not allow anticipating the intensity of each event. There may be a month with a negative anomaly and, even so, a strong storm or a day with abundant rainfall may be recorded. The balance depends on how much it rains throughout the entire period. Sectors close to the Patagonian Andes could record monthly accumulations below the October average (Illustrative Image Infobae)Climate anomalies are differences between a forecast value and the historical average of an area. If the model estimates a positive rainfall anomaly, it projects monthly accumulations above the average. If it anticipates a negative anomaly, it expects records below the usual ones. This type of meteorological product does not replace daily forecasts. The monthly forecast does not report exactly when a storm will arrive, how much it will rain in a given city or which areas could experience intense events. The map does not constitute a forecast of accumulations by locality or of the conditions of each day. Its contribution consists of showing a broad-scale orientation, useful for recognizing trends and planning ahead. The October update incorporates a trend of average temperatures below normal values in much of central and western Argentina. The estimated deviations are between -0.5°C and -2°C, with a more marked signal in Andean and central-western sectors. A negative thermal anomaly means that the average temperature of the month could be below the historical reference. There may be mild or warm days, as long as other periods with lower readings compensate for those records in the monthly calculation. Northeastern Argentina and part of the east show a less defined signal, close to normal parameters or with slightly negative deviations. For that reason, the scenario does not allow defining October as a cold month uniformly across the entire national territory. A negative average temperature anomaly does not confirm frosts nor does it allow estimating specific minimum temperatures. The value corresponds to a monthly average, which may include days with high, low or near-normal temperatures. Specific events will have to be evaluated with daily forecasts and meteorological alerts.