India: Adverse weather forecast across southern regions through at least Jan. 8

Adverse weather is forecast across parts of southern India through at least Jan. 8. A low-pressure system is expected to bring isolated heavy rainfall accompanied by thunderstorms across the region over the coming days. Strong wind gusts, lightning, and hail storms may accompany thunderstorms. Heavy downpours could trigger flooding in low-lying areas and landslides on unstable slopes. Strong winds may cause property damage and power outages.

The India Meteorological Department (IMD) has issued orange heavy rainfall, thunderstorm, and lightning warnings (the middle level on a three-tier scale) for Kerala State and yellow warnings across southern interior Karnataka State, Lakshadweep Union Territory, Puducherry Union Territory, and Tamil Nadu State Jan. 5. Further orange warnings are in place across Puducherry Union Territory and Tamil Nadu State Jan. 7 and yellow warnings across other parts of the affected area Jan. 6-8. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change 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 the soil has become saturated by heavy rainfall.

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.