Aug. 5, 2019
Monsoon downpours will continue to bring the risk for flooding to parts of India during the week ahead.
Heavy rains 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 much-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.
Over the course of this week, this tropical low will creep farther and farther inland, spreading waves of heavy rain with it.
There will be the risk for heavy downpours that can reduce visibility and also lead to flash flooding. With how dry the soil is following several months of below-normal rainfall, 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.
The heaviest rain will stretch from the coast of Odisha 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 in 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 downpours will continue for the week, bringing heavy rainfall from coastal Karnataka and Maharashtra, including Mumbai. The city had over 1,400 mm (56 inches) of rainfall in the month of July.
Mumbai and surrounding areas can expect 150-300 mm (6-12 inches) of rainfall in the week ahead with local amounts up to 450 mm (18 inches).
Flooding and transportation delays are expected during the heaviest rainfall and mudslides will be possible in areas of rugged terrain.