India: Adverse weather forecast across southern regions through at least Dec. 2

Severe weather is forecast across southern India through at least Dec. 2 following the formation of Cyclone Fengal over the southwestern Bay of Bengal on Nov. 29. The Indian Meteorological Department (IMD) issued a bulletin and warnings on Nov. 29 of thunderstorms, lightning, and heavy rain across southern India through Dec. 2.

The IMD has issued the following severe weather warnings:

Nov. 29

• Red thunderstorm, heavy rain, and lightning warnings (the highest level on a three-tier scale): Puducherry, Rayalaseema, and Tamil Nadu.

• Orange thunderstorm, heavy rain, and lightning warnings: Coastal Andhra Pradesh.

Nov. 30

• Red thunderstorm, heavy rain, and lightning warnings (the highest level on a three-tier scale): Coastal Andhra Pradesh, Puducherry, Rayalaseema, and Tamil Nadu.

• Yellow heavy rain warnings: Telangana, southern interior Karnataka, and Kerala.

• Yellow thunderstorm and lightning warnings: Southern interior Karnataka, and Kerala.

Dec. 1

• Orange thunderstorm, heavy rain, and lightning warnings: Southern interior Karnataka, Kerala, Puducherry, and Tamil Nadu.

• Yellow heavy rain warnings: Rayalaseema and coastal Andhra Pradesh.

• Yellow thunderstorm and lightning warnings: Telangana.

Dec. 2

• Orange thunderstorm, heavy rain, and lightning warnings: Southern interior Karnataka and Kerala.

• Yellow heavy rain warnings: Telangana.

• Yellow thunderstorm and lightning warnings: Coastal Karnataka, Puducherry, and Tamil Nadu.

Officials could update and extend the coverage of 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.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

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 regional airports.

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.

Flooding could heighten the threat of disease outbreaks. Backflow from drains 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 water-borne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.