India: Adverse weather forecast across northeastern regions through at least April 21

Severe weather is forecast across northeastern India through at least April 21. The Indian Meteorological Department (IMD) has issued a special message warning of light-to-moderate rainfall accompanied by thunderstorms and lightning over the northeastern regions April 16-21. As of early April 16, the IMD has issued the following severe weather warnings across the affected area:

• Orange thunderstorm, heavy rain, lightning, and hailstorm warnings (the middle level on a three-tier scale): Sikkim and northern West Bengal states April 16 and Arunachal Pradesh, Assam, Manipur, Mizoram, Nagaland, and Tripura states April 20.

• Yellow thunderstorm, heavy rain, strong wind, and lightning warnings: the rest of the affected area through April 21.

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.