Next 10 (Hot and Dry) Days Important Determining Central Brazil Summer Drought Risk

Fig. 1: Deep layer soil moisture deficits highlight where in Brazil summer of 2023-24 drought is most likely intense. In green, are areas of recent deep layer soil moisture improvement.

Discussion: The region of primary drought concern for summer 2023-24 is across Northern Brazil (Fig. 1). Deep layer (10-200 CM) soil moisture anomalies identify this risk area. Recently, the deep layer soil moisture deficit region has expanded southward into Central Brazil warranting drought concern for Brazil’s northern crop areas. During the past 7-10 days, the deep layer soil moisture deficit has eased slightly. During the next 10 days, the Central/East-central Brazil region is likely to encounter harsh anomalous hot and dry conditions (Fig. 2-3). However, in the 11-15-day period and day-15, the forecast for Central Brazil trends wetter (Fig. 4-5). Amplified high pressure over Southeast Brazil is the catalyst to the upcoming hot and dry period. A frontal boundary extending northwest from a low-pressure area east of Argentina invites tropical moisture across Central Brazil in the extended-range and likely to continue into the 16-20-day period. Climate Impact Company continues to project drought concerns for NOV/DEC/JAN in Central Brazil. However, based on the 2+ week operational forecast, the effectiveness of the 10-day hot/dry period ahead may dictate how dry soil conditions are as meteorological summer approaches.

Fig. 2-5: Mega-cluster ensemble upper air forecast through the next 15 days and attendant very hot/very dry (and wet) risk areas.