Pune: Aug has only just begun, but the city has already recorded more rainfall than its June-Aug seasonal normal. This comes even as India Meteorological Department (IMD)’s latest long-range outlook indicated below-normal rainfall over Maharashtra in Aug, an unexpected contrast in a monsoon season that has already reshaped the city’s rainfall record.According to IMD’s 1971-2020 climatological normals, Pune receives an average of 166.3mm rainfall in June, 189.1mm in July and 145.5mm in Aug. Yet, with most of Aug still remaining, the city has already logged 630.1mm of rainfall so far this season, overshooting the three-month normal of 500.9mm by more than 120mm.IMD scientist SD Sanap attributed Pune’s exceptional rainfall to a succession of favourable weather systems through July rather than a single heavy rain event. “A large share of Pune’s seasonal rainfall came during the first eight days of July. The city received rainfall comparable to its normal seasonal accumulation within that short period because of a combination of highly favourable weather systems,” he said.July, in particular, was unusually active. Sanap said the intense spell between July 1 and 8 was triggered by a depression over the Bay of Bengal. At the same time, an offshore trough and an east-west shear zone around 21°N created ideal conditions for widespread and heavy rainfall across Pune city and district, he said.Although rainfall activity weakened between July 9 and 15, another system developed over the Bay of Bengal, reinvigorating the monsoon flow and reviving rainfall over the region. Later in the month, a westward-moving weather system, coupled with a low-pressure area over southwest Rajasthan and adjoining regions, enhanced moisture incursion and further strengthened monsoon currents, bringing another spell of widespread rain.Sanap said four low-pressure systems influenced the region during July. “Of these, two intensified into depressions, one became a well-marked low-pressure area, while another remained a low-pressure area over land. In sharp contrast, June saw no low-pressure systems form at all,” he said.Beyond these synoptic systems, atmospheric features like the offshore trough and the east-west shear zone played a crucial role in amplifying rainfall. Repeated strengthening of the monsoon circulation ensured a sustained supply of moisture over Pune and the adjoining Ghat regions, supporting prolonged rainfall activity.“The cumulative effect of these successive systems and supportive atmospheric conditions resulted in exceptionally high monthly rainfall and helped Pune cross its seasonal rainfall normal much earlier than usual,” Sanap said.
