Brazil, Paraguay: Adverse weather forecast across parts of southern Brazil and much of Paraguay through at least Oct. 11 /update 1

Severe weather is forecast across parts of southern Brazil and much of Paraguay through at least Oct. 11. Heavy rainfall and thunderstorms are forecast across the region; strong winds, lightning, and possible hail may accompany storms. Heavy downpours could lead to flooding in low-lying areas and landslides on unstable slopes. Strong winds may cause property damage and power outages.

As of early Oct. 9, Brazil's National Institute of Meteorology (INMET) has issued orange storm warnings (the middle level on a three-tier scale) across parts of southwestern Parana, northern and western Rio Grande do Sul, and western Santa Catarina states. Rainfall amounts of 3-6 cm (1.2-2.4 inches) per hour or 5-10 cm (2-4 inches) in 24 hours, winds gusting between 60-100 kph (37-62 mph), and hail are likely in the affected area. Yellow storm warnings are in place across most of the rest of the affected area in Brazil.

Paraguay's Directorate of Meteorology and Hydrology has issued a special weather bulletin for storms across central, eastern, and southern regions of the country Oct. 9-11. Daily rainfall totals of 6-9 cm (2.4-3.5 inches) and winds gusting up to 100 kph (62 mph) are expected in eastern regions and rainfall amounts of 3-5 cm (1.2-2 inches) and winds gusting up to 80 kph (50 mph) are expected across central and southern areas. A short-term warning for moderate-to-strong rainfall with thunderstorms, moderate-to-strong wind gusts, and occasional hail has also been issued across much of the country early Oct. 9.

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

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 are 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. 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.