Heavy rain to flood eastern India next week while monsoon continues in southwest

By Courtney Spamer, AccuWeather meteorologist

Heavier, tropical rain is expected to move across eastern India next week after a dry spell.

Monsoon downpours have spread over much of India in recent weeks bringing the country vital rainfall for water supplies and agriculture. However, not every region has received the needed rainfall.

India's southeast state of Tamil Nadu has been largely missed by any significant rainfall since the start of the yearly southwest monsoon. Some downpours dampened northeastern parts of the state, including Chennai, in late July. However, this has not been able to put more than a dent in the water shortages currently affecting the city of approximately 10 million people.

It's also been drier than normal in northeastern parts of India, including parts of West Bengal, Jharkhand and Odisha. The city of Kolkata had only 110 mm (4.35 inches) of rainfall in July, well shy of the average of 300 mm (11.85 inches) for the month.

The southwest monsoon has kept places along the western shores, including Mumbai, quite wet so far this summer, helping to replenish water supplies. While this monsoonal moisture is expected to continue in western parts of the country, a new low will bring tropical moisture to eastern parts of India.

After passing over the Indochinese peninsula, this low, which was once Tropical Storm Wipha in the Western Pacific Ocean, will emerge into the waters of the Bay of Bengal early in the week.

The weather pattern is not conducive for Wipha to redevelop in the Bay of Bengal; however, it will bring a wave of heavy rainfall into what has recently been a dry spot in eastern India.

From late in the weekend through the middle of next week, this tropical low will creep farther and farther inland, spreading with waves of heavy rain.

This rain will bring heavy downpours that can not only reduce visibility but also lead to flash flooding. With how dry the soil has been so far in July, the ground will have difficulty absorbing a lot of rain in a short period of time. Standing water will last well after rainfall has ended, possibly cutting off some villages and cities.

RELATED: 
India Weather Center 
Interactive India weather satellite 
What's the difference between heat exhaustion and heat stroke?

The heaviest rain will stretch from the coast of Odisha and West Bengal to Uttar Pradesh Monday through Wednesday. Total rainfall amounts of 75-150 mm (3-6 inches), with an AccuWeather Local StormMax™ of 225 mm (9 inches), are possible by the middle of the week across some locations.

Late in the week, the low will continue to move across India and toward the Arabian Sea. This will spread even more heavy rainfall to western India.

Meanwhile, the heavy southwest monsoon will continue for the next week, bringing heavy rainfall from coastal Karnataka and Maharashtra, including Mumbai. The city had over 140 cm (56 inches) of rainfall in the month of July.