South America: Monsoon storms likely in most of South America through April 2023

Event

The South American Monsoon is forecast to produce regular showers and thunderstorms in parts of northern Argentina, Brazil, Bolivia, northern Chile, Paraguay, Peru, and Uruguay through at least the end of April 2023. The rains typically begin in early October over the Brazilian Highlands and spread northwards as the monsoon progresses.

Severe storms could produce torrential downpours, flash flooding, hail, and strong winds. Normally dry streams, creeks, and arroyos could quickly become inundated with floodwaters. Wind gusts of up to 80 kph (50 mph) have the potential to produce power outages throughout the affected area. Localized disruptions could persist well after hazardous events have concluded - it could take days or weeks for floodwaters to subside and for authorities to clear landslide debris. Rural communities and informal settlements often suffer the greatest damage and casualties during such events due to their poor infrastructure.

The potential for flooding is highest in low-lying communities near watercourses in recognized floodplains. Rivers and their tributaries in major basins such as the Amazon, Iguacu, La Plata, and Parana regularly overflow their banks during periods of intense rainfall. Flash floods, which often occur with little-to-no warning, can pose a threat to communities downstream of major rivers or dams in the event of infrastructural failure. Urban flooding is possible in areas with poorly maintained, inadequate, or non-existent drainage systems. Storm surges may trigger flooding in coastal areas. Landslides and mudslides are possible in hilly and mountainous areas, including the Andean Mountains.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around 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 flight delays and cancellations at domestic and international airports in the affected area over the coming months. Authorities may temporarily suspend port operations or close beach fronts if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.

Health
The threat of disease outbreaks is elevated during the monsoon season. Backflow from drains that has mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become a breeding ground for mosquitoes and bacteria, increasing the incidence of insect- and waterborne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.

Advice

Monitor local media for updates and advisories on weather conditions. Confirm all transport reservations prior to travel. Make allowances for possible supply chain disruptions throughout the monsoon season, particularly in areas affected by flooding and or/landslide events.

Stay away from streams, creeks, arroyos, and other watercourses that may be prone to flash flooding. Seek updated information on road conditions before driving or routing shipments through areas where severe weather or flooding is forecast. Plan for possible supply chain disruptions if routing shipments through South America. Do not attempt to drive on flooded roads. Confirm flights.

Resources

Argentina Servicio Meteorologico Nacional
Direccion Meteorologica de Chile
Paraguay Direccion de Meteorologia e Hidrologia
Peru Servicio Nacional de Meteorologia e Hidrologia
Uruguay Direccion Nacional de Meteorologia