South America: Water deficits to persist in central Brazil, Chile, southern Argentina

The Big Picture
As seen in the 12-month map (below), widespread water deficits – including vast areas of exceptional deficit – are forecast from Brazil’s northern states southward through the center of the country and deficits trace a clear path along the Amazon River and its tributaries. Exceptional surpluses are expected to persist in La Rioja and Mendoza, Argentina, and moderate surpluses in central Paraguay, Uruguay and Entre Rios, Argentina.

Impacts
“Severe drought conditions at the start of the dry season have set the stage for extreme fire risk in 2016 across the southern Amazon,” warns NASA Earth scientist Doug Morton, co-creator of the Amazon fire forecast. The Brazilian states of Pará, Mato Grosso and Amazonas have the highest fire risk according to the forecast, as El Niño has reduced rainfall during the wet season leaving conditions at the start of the 2016 dry season the worst since 2002.

A study by researchers at the Universities of Exeter and Leeds has found that, not just by killing trees but also by slowing their growth, the droughts of 2005 and 2010 shut down the Amazon Basin's carbon sink known as the "green lungs."

Forecast Breakdown
The 3-month maps (below) for the same 12-month period illustrate conditions in more detail.

Exceptional water deficits (greater than 40 year expected frequency) are in the forecast for much of Brazil north of São Paulo from July into October. Moderate (5 to 10 year) to extreme (20 to 40 year) deficits are forecast for: Suriname, French Guiana, northern Venezuela, southwestern Colombia, Peru, southern Bolivia and rivers in Bolivia, much of Chile, southern Argentina, Tierra del Fuego, and the Falkland Islands. A band of moderate deficits is forecast to emerge in the State of Santa Catarina in southern Brazil. Surpluses may persist in Uruguay, though not as severe as in prior months. Surpluses are also forecast to persist in central Argentina.

In November and December the extent of exceptional water deficits in Brazil is forecast to diminish though extreme to exceptional deficits will persist along the Amazon River and in the northeastern states of Amapá and Maranhão. Widespread deficits are expected to emerge across northern South American countries. In Chile deficits are forecast to persist though with diminished severity during this period. Likewise, deficits in some parts of southern Argentina will diminish, except along the Rios Chubut, Chico, and Negro.

(It should be noted that forecast skill declines with longer lead times.)