Thunderstorm activity will continue over many parts of the State till the weekend ahead of the formation of a weather system over Bay of Bengal.
With westerly winds strengthening over the region, it would lead to convective activity and thunderstorms. The low pressure area brewing over the Bay of Bengal would also influence a rise in mercury level and rain over the State. Chennai may also get light rain during the next two days.
Officials of the Meteorological Department said scattered rainfall will continue over Tamil Nadu till May 22. On Thursday, heavy spells of rain may occur at a few places over the Nilgiris, Theni, Villupuram, Tirupattur and Vellore. Thunderstorms are also likely in interior and coastal parts of the State till May 23. However, the intensity and spatial spread of the rainfall may decrease once the weather system forms over the Bay of Bengal around May 22.
During the past 24 hours ending 8.30 a.m. on Wednesday, Udhagamandalam received 4 cm rain. This was followed by 3 cm of rain over Krishnarayapuram in Karur district. The Meteorological Department has also forecast that southwest monsoon may advance into south Andaman sea and adjoining southeast Bay of Bengal around Friday.
S. Balachandran, Deputy Director General of Meteorology, Chennai, said the low pressure area is expected to form over north Andaman sea and adjoining east-central Bay of Bengal on Saturday. It is likely to become a cyclone and move towards West Bengal and Orissa coasts. Madden-Julian Oscillation (MJO), a global weather phenomenon, had initially influenced the formation of cyclone Tauktae in Arabian sea. With other favourable weather conditions, MJO, the east-moving pulse of clouds and rain, is also aiding the forming of low pressure over Bay of Bengal. This also strengthened the monsoon current and triggered onset of SW monsoon over the Andaman sea, he added.
The department has also warned fishermen not to venture into sea on May 22 and May 23 as strong southwesterly winds with speed reaching 45 to 55 km per hour is likely along and off Tamil Nadu coast.
On Wednesday, the city recorded a maximum temperature of 35.2 degree Celsius and this is set to further increase to 37 degree Celsius till Friday, according to the department.