By Meghak Gupta 
Early Monday morning, Mumbai experienced its most significant one-day rainfall since 2019, catching both residents and meteorologists off guard. The deluge, which inundated several parts of the city with over 300 mm of rain within hours, highlighted gaps in weather forecasting models and left experts baffled.
The Indian Meteorological Department (IMD) attributed this unprecedented rainfall to the sudden strengthening of an offshore trough around midnight, a phenomenon that wasn’t adequately captured by existing weather predictions.
According to data from the Brihanmumbai Municipal Corporation (BMC), the eastern suburbs bore the brunt of the downpour, with areas like Vikhroli and Powai recording 315.6 mm and 314.5 mm of rain respectively. In contrast, Santacruz, a key recording station, registered 268 mm of rainfall, while Colaba recorded only 84 mm over the same period.
IMD scientists noted that while a nowcast warning was issued around midnight, the intensity of rainfall escalated dramatically after 2:30 am. Sushma Nair from IMD Mumbai explained, “Santacruz initially recorded 40.9 mm by 2:30 am, followed by a rapid surge to 210.9 mm between 2:30 am and 4:00 am.”
The unexpected nature of the downpour drew criticism as the city struggled with waterlogged streets throughout Monday. An IMD official acknowledged, “Our models failed to predict this intense, localized weather system. The offshore vortex responsible for these rains was beyond the scope of our current forecasting capabilities.”
Meteorologists and climate experts, including Professors from IIT-Bombay, echoed these sentiments, highlighting that multiple models, including the ECMWF and NCEP-GFS, had underestimated the rainfall. They attributed the anomaly to the northward expansion of the southwesterly jet, which suddenly brought moisture directly over Mumbai.
Despite a temporary lull in suburban rain activity, the island city continued to receive heavy showers, prompting the IMD to issue a red alert until Tuesday morning. Sunil Kamble, IMD Mumbai’s director, warned, “We expect over 100 mm of rainfall in the next 12 hours, necessitating the red alert.”
As Mumbai braces for continued heavy rainfall, the IMD has extended a yellow alert for Tuesday across Mumbai and its neighboring districts. The city remains on high alert, navigating unpredictable weather patterns that defy conventional forecasting models.
Stay updated with the latest developments on Mumbai’s weather challenges as experts work to understand and predict these complex weather events.