12 Jul 2023 | 05:15 AM UTC
Brazil: Adverse weather forecast across southern regions through at least July 15
Heavy rainfall and strong winds likely over southern Brazil through July 15. Flooding, landslides, and transport disruptions possible.
Event
Heavy rainfall and strong winds are forecast across southern Brazil through at least July 15 due to an extratropical cyclone. Heavy downpours could trigger flooding in low-lying areas and landslides on unstable slopes. Transport disruptions and power outages are also possible in affected areas.
As of late July 11, Brazil's National Institute of Meteorology (Inmet) has issued the following weather warnings across the affected area:
Orange (the middle level on a three-tier scale) warning for heavy rainfall: Rio Grande do Sul and Santa Catarina states. 3-6 cm (1-2 inches) of rain per hour or 5-10 cm (2-4 inches) of rain per day, with strong winds of 60-100 kph (37-62 mph) and hail are forecast.
Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.
Winds are likely to intensify over eastern Rio Grande do Sul State and over the mountainous areas of the state the afternoon of July 12 before spreading over Santa Catarina State July 13, and over Rio de Janeiro State July 15. Storm surge is possible between Laguna and Campos dos Goytacazes July 13, with waves of up to 4 meters (13 feet). Frost is possible in the mountainous areas of Rio Grande do Sul and Santa Catarina states July 14 and in southern Sao Paulo State and across the Mantiqueira Mountains July 15.
Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. In developed areas with easily overwhelmed stormwater drainage systems, additional urban flooding is also possible. 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 rainfall has saturated the soil. Power outages and disruptions to telecommunications services are likely where significant flooding, landslides, or strong winds impact utility networks.
Transport
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. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and track inundation. Localized business disruptions may occur in low-lying areas.
Advice
Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.
