Brazil, Uruguay: Adverse weather forecast across southern Brazil and northern Uruguay Oct. 1

Thunderstorms and heavy rainfall are forecast across parts of southern Brazil and northern Uruguay Oct. 1. Storms may be accompanied by strong wind gusts, lightning, and possible hail. heavy downpours may trigger flooding in low-lying areas and landslides on unstable slopes. Strong winds could cause property damage and power outages.

As of early Oct. 1, Brazil's National Institute of Meteorology (INMET) has issued orange storm warnings (the middle level on a three-tier scale) across the southern half of Rio Grande do Sul State. Rainfall totals of 3-6 cm (1.1-2.4 inches) per hour or 5-10 cm (2-4 inches) per day are forecast, as well as winds of 60-100 kph (37-62 mph) and possible hail storms. Yellow storm warnings are in place across the rest Rio Grande do Sul and parts of southern Santa Catarina State.

Uruguay's Institute of Meteorology (Inumet) has issued an orange warning for strong storms and heavy rainfall (the middle level on a three-tier scale) across Artigas and Salto and parts of northwestern Paysandu, northwestern Rivera, and northern Tacuarembo departments. A yellow warning for strong storms and heavy rainfall is in effect across much of the rest of northern Uruguay.

Officials could update and possibly extend the coverage of weather alerts over the coming hours and days.

The storms could produce rounds of heavy precipitation, strong winds, and isolated thunderstorm activity in the affected area. Sustained heavy rainfall could trigger flash and areal flooding. Such flooding is possible in low-lying communities near watercourses and other large bodies of water and in urban areas with easily overwhelmed stormwater drainage systems. Sites downstream of large reservoirs may be subject to flash flooding after relatively short periods of intense rainfall. Sporadic power outages may occur throughout the affected area.

The severe weather will likely contribute to transport disruptions across parts of the impacted region. Traffic and commercial trucking delays might occur along regional highways. Flooding downpours could inundate some low-lying roads in areas with poor drainage. Strong winds might also pose a hazard to high-profile vehicles. Hazardous weather conditions might cause flight delays and cancellations at regional airports.