Early southwest monsoon rainfall in Mangalore an all-time record for May

The pristine beach of Panambur in Mangaluru, Karnataka witnessed a record single-day rainfall for the month of May. The rainguage at Panambur recorded 33 cm of rain in 24 hours starting from May 29, 0830 hours to May 30, 0830 hours.

Just about 10 km into the land, at the Mangaluru airport in Bajpe town, the India Meteorological Department (IMD) recorded 28 cm rainfall, lower than that on the coast. 

The IMD declared the onset of monsoon in Kerala on the morning of May 29. Later on in the day, a vortex formed out of a well-marked low-pressure area along the Mangaluru coast—carrying immense moisture—remained at the same spot and dissipated in parts of Karnataka, with reducing intensity over the land. 

After these rains, the IMD on May 30 declared the arrival of Monsoon in Mangaluru. 

A well-marked low-pressure area (WML, in IMD terminology) near Karnataka-Kerala coast facilitated the pull for the early advance of the southwest monsoon winds into Kerala, or mainland India. The WML then shifted upwards—on the same day when IMD declared monsoon onset in Kerala, May 29—till latitude close to Mangaluru, and transformed into a vortex.

The process of vortex formation involved fresh convection or the upward movement of moisture from sea surface, and since the vortex did not move much during the day on May 29, the region in its immediate vicinity received massive rains. 

A vortex is nothing but a circular (or cyclonic) wind circulation, or a very weak form of a cyclone (but not a cyclone). The WML which caused the vortex and subsequent precipitation has now become “less marked”, meaning it has shed power, according to IMD. 

As the vortex was situated very near to the coast, areas farther from the coast received lesser rains, according to IMD data. Heavy rain has been forecast by IMD’s Bengaluru centre in various districts of Karnataka till June 2, their latest release said.