A storm system will move out of the Andes and across central Argentina on Thursday and Friday bringing heavy rain and localized severe thunderstorms to a large portion of Argentina, Uruguay, Paraguay and southeastern Brazil.
The storm system will move eastward on Thursday resulting in rain and thunderstorms from Neuguen and Mendoza states into Rio Negro, La Pampa and western Buenos Aires states.
As the storm moves eastward Thursday night, rain will spread across the remainder of Buenos Aires state. Rain is expected to begin in Buenos Aires late Thursday night and continue into Friday. The heaviest rainfall will pass south of the city, with rainfall amounts of around 13 mm (0.50 of an inch). Areas across western and southern Buenos Aires state can expect rainfall of 25-50 mm (1-2 inches) resulting in localized flooding problems.
North and west of Buenos Aires, strong thunderstorms will develop Thursday night, impacting areas from Cordoba to Chaco and Tucuman states.
These strong thunderstorms will be capable of producing torrential downpours resulting in flash flooding, along with the threat for damaging winds and hail.
The worst of the storms will shift into northeastern Argentina, southern Paraguay and the Brazilian state of Rio Grande do Sul. Farther south, heavy rain and thunderstorms will move across Uruguay and eastern Buenos Aires state before moving over the Atlantic Ocean by the end of the day.
By Friday night, the worst weather will be found across Paraguay and southeastern Brazil where thunderstorms will rumble through the cities of Asuncion and Porto Alegre.
This front will continue to lift northward over the weekend resulting in scattered showers and thunderstorms across eastern Brazil, including around the cities of San Paulo and Rio de Janeiro.