Abstract

The ability to anticipate meteorological extreme events beyond the synoptic range of ~1 week offers direct applications, e.g. to limit their ecological and socio‐economical impacts. This study focuses on precursors of summer (December‐February, DJF) warm events, particularly heat waves, in central Chile (CCh), which are typically induced by low‐level anticyclonic anomalies located to the south of this region. Considering that such atmospheric configuration can be part of a large‐scale wave‐train circulation pattern located upstream of CCh, we investigate signals that might provide guidance concerning the genesis of warm events in CCh. For a historical period (DJF 1872‐2010) based on the 20th Century Reanalysis version 2 (20CR), our results present teleconnections that indicate higher probabilities of occurrence of such warm events with respect to expected climatological values. These signals can be monitored at least ~2 weeks in advance. Specifically, we explore the relationship between warm events in CCh and 1) the Madden‐Julian Oscillation (MJO) as a tropical source of variability, and 2) an extra‐tropical index (ETI), representative of the internal dynamics of the Southern Hemipshere mid‐latitudes, presented as an original contribution from this study following a novel approach. Both signals, and apparently their constructive superposition, seem to contribute to the organization of the large‐scale circulation anomalies leading ultimately to heat waves in CCh. We confirm these results for recent decades (DJF 1981‐2020) using temperature observations and further datasets, namely the NCEP‐NCAR Reanalysis (NNR) and the Climate Forecast System Reanalysis versions 1 and 2 (CFSR and CFSv2, respectively). Finally, we describe three recent heat wave events in CCh (DJF 2019‐2020) to illustrate the suitability of this conceptualization.