Early Winter Heat and Dryness in South America

Fig. 1-2: The GFS 15-day temperature and precipitation anomaly forecast for South America.

Discussion: Central, southwest, and interior southeast portions of Brazil have observed a wet 30-day period dating back to late May. During the past week, central and southern portions of Argentina have received plenty of rain. However, the latest 15-day outlook projects an amplified upper-level high-pressure ridge centered over west-central South America. As a result, the South America climate pattern into the early middle third of July turns unusually hot (Fig. 1). The subsidence produced by the upper ridge propels an exceptionally dry climate for most of Brazil and Argentina in the latest 15-day outlook (Fig. 2). Maximum temperature exceeds 35C across interior Brazil and as far south as Northern Argentina during the medium range. Beyond 15 days, the ensembles ease the amplitude of the upper ridge in Argentina while Brazil stays hot and dry.