Cyclone Burevi, which degraded to a deep depression on Friday morning and remained stationary over the Gulf of Mannar for several hours, further weakened into a depression. Nonetheless, it was one of the unusual weather systems that covered most of the state with rain.
It may continue to have an impact on Tamil Nadu, and the rain wave may last two more days, even if it is not of the same intensity. Heavy to very heavy rains can occur in one or two places on Saturday.
As a depression, it will slowly move west-southwest through Ramanathapuram into southern Kerala and lose its strength to become a well-marked low-pressure area on Saturday.
S. Balachandran, Deputy Director General for Meteorology for Chennai, said that as the meteorological disturbance remained stationary for several hours over the Gulf of Mannar, it pushed moisture towards the ground and brought heavy rain. The external power strips of the stagnant system also brought rain to Chennai.
More than 50 weather stations received heavy rains of up to 12 cm during the last 24 hours until Friday morning. A total of 11 stations had very heavy rains, and five locations received extremely heavy rains of more than 24 cm. Kollidam in Nagapattinam district received 36 cm.
Only the far southern regions like Kanniyakumari and some areas of the western Ghats, including Coimbatore, have yet to receive enough rain. “In a single day, the weather system helped reduce the state’s rainfall deficit to a mere 2% from 12% the day before. Tamil Nadu’s total rainfall is now 36.2 cm against its seasonal normal of 37 cm since October 1, ”Balachandran said.
On the heavy rain that also spread to the northern parts, Balachandran said that vertical wind shear (a sudden change in direction or speed over a short distance in the atmosphere) had displaced the rain bands of the main meteorological system. . “This system has broadly covered the central and southern parts and has also impacted the northern region,” he said.
Chennai and Ennore received 2cm of rain until 7pm on Friday. The Indian Meteorological Department has forecast that moderate rains, which can sometimes be heavy, are likely to occur in Chennai for two days.
Senior meteorologist YEA Raj noted that this system was unusual in that there were no clouds over the nearest areas like Kanniyakumari or Tirunelveli. There was a disconnect between the center of the storm and the rain clouds.
In addition to the wind shear that pushed the clouds northward, the weather system also tilted northward with height due to a colder temperature prevailing in northern India. “Cyclone Nivar gave rain along its path. This system gave more rain and covered more areas ”.
The system was stationary for many hours possibly because it was trapped in the quiet region of the upper troposphere, where the winds would be weak, he said.
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