A slow-moving storm will unleash several days of heavy rain and thunderstorms on parts of Argentina and Uruguay this week.
The greatest threat for flooding will be from Monday afternoon into Wednesday morning as repeated downpours occur from Vera and Santa Fe to Salto and Treinta y Tres.
This region is expected to receive 50-100 mm (2-4 inches) of rain with local amounts over 150 mm (6 inches).
This region already received 25-75 mm (1-3 inches) of rain on April 1, causing river levels to rise and resulting in saturated ground ahead of the new round of rainfall. This combination of recent rain and additional heavy rainfall will cause a high risk for widespread flooding.
Significant travel delays are expected and some areas could become isolated from outside aid due to flooding and mudslides making roadways impassible.
New rainfall of 25-50 mm (1-2 inches) will be common to the north and south of the hardest-hit areas. Areas likely to experience locally heavy rainfall, with a lower threat for flooding include: Rosario, Buenos Aires and Montevideo.
A slight shift southward in the storm track could bring heavier rainfall into these cities causing flooding problems. Even if the heaviest rain remains to the north, downpours can still briefly impact travel and result in flooding in poor drainage areas.
The weather will improve from west to east on Wednesday with any rainfall limited to the morning in Buenos Aires and Montevideo.
Dry weather will be brief as another storm develops over northern Argentina on Wednesday night, bringing another round of downpours to northeast Argentina and much of Uruguay from Thursday into Friday. New rainfall of 25-50 mm (1-2 inches) is possible with this storm which would worsen flooding problems across the region.
Total rainfall from Monday through Saturday could exceed 300 mm (12 inches) in the hardest-hit areas, which may include Salto.
Long-range forecasts indicate a period of dry weather is expected from Sunday into the following week which would allow flood waters to recede and benefit cleanup efforts.