Brazil: Adverse weather forecast across southern regions through at least May 6 /update 1

Severe weather is forecast across southern Brazil through at least May 6. Rainfall totals of more than 10 cm (4 inches) are possible across the region.

As of May 1, Brazil's National Institute of Meteorology (INMET) has issued red heavy rainfall warnings (the highest level on a three-tier scale) across most of Rio Grande do Sul and far southern Santa Catarina states. Orange heavy rainfall warnings are in place across the rest of the affected area. Officials could update and extend the coverage of the relevant weather alerts over the coming days.

Rio Grande do Sul State is the worst affected by heavy rainfall, flooding, and landslides. Authorities have confirmed that 10 people were killed and 11 others injured, with at least 21 people across the state missing. More than 19,000 people have been affected, with more than 3,400 displaced and around 1,500 stranded. Several towns are isolated due to damaged or flooded roads or bridges. Reports indicate power and water outages affecting tens of thousands of people across parts of the state. Authorities have suspended classes statewide through May 3.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides remain possible in hilly or mountainous areas, especially where heavy rain has saturated the soil. Power outages and disruptions to telecommunications services may occur where significant flooding, landslides, or strong winds impact utility networks.

Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel in affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather could also trigger intermittent flight delays and cancellations at airports in the affected regions, though these are unlikely to be severe or prolonged. Authorities may temporarily suspend port operations or close beach fronts along the Atlantic coast if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and track inundation. Localized business disruptions may occur in low-lying areas.