Brazil: Adverse weather forecast across southern regions through at least May 6 /update 2

Severe weather is forecast across southern Brazil through at least May 6. Heavy rainfall since April 29 has resulted in widespread flooding and landslides. Rio Grande do Sul State is the worst affected; authorities have declared a state of calamity for 180 days.

Officials have confirmed that the severe weather killed 29 people and injured 11 others, with at least 60 people across the state missing. The death toll is likely to rise as recovery efforts continue. Over 67,800 people have been affected, with almost 15,000 displaced and 1,500 stranded.

A dam of the 14 de Julho hydroelectric power plant in Cotipora Municipality, between Cotipora and Bento Goncalves cities, has partially collapsed and will likely suffer further damage. The Blang, Dal Bo, and Santa Lucia dams also risk rupturing. The Taquari and Cai rivers are also in danger of flooding, and authorities have advised residents in the vicinity and downstream of the rivers and dams to evacuate the area. Almost 140 sections across 60 highways are totally or partially closed. Damaged or flooded roads or bridges have isolated several towns. Reports indicate that power outages are affecting more than 329,000 people, and water outages are affecting more than 541,000 people across the state. Around 48 cities also do not have telecommunications or internet services. Authorities have suspended classes statewide through May 3.

As of May 2, 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.

Sustained heavy rainfall could trigger further 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 regional airports, 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.