A slow-moving cold front that already produced flooding rainfall across parts of Argentina and southern Uruguay will shift northeast during the first half of the week ahead.
The front will then stall over southeast Brazil as a wave of low pressure moves along it from Tuesday into Wednesday, leading to rounds of rain over the same areas.
As a result, 50-100 mm (2-4 inches) of rain will fall leading to flooding and an elevated risk for mudslides.
The heaviest rain will shift to the north and east of Buenos Aires, Argentina and Montevideo, Uruguay where 50-100 mm (2-4 inches) fell Saturday into Sunday.
Downpours will briefly target Asuncion, Paraguay Sunday night before moving to the east by Monday.
From Monday into Wednesday the greatest threat for flooding will include Posadas, Argentina and Porto Alegre, Brazil but will remain to the southwest of Curitiba, Brazil.
The front will finally lift northward late Wednesday into Thursday bringing relief to the areas that experience the heaviest rainfall early in the week.
Several days of largely dry weather will follow as high pressure builds across Argentina and Uruguay.