Southern parts of the city and suburbs received heavy rainfall accompanied by heavy winds on Monday evening which brought much-needed respite after a hot day.
The showers in many localities, including Adyar, Velachery, Tambaram, Okkiam Thoraippakkam, Pammal and Chromepet, lasted for over two hours. Traffic on arterial roads was thrown out of gear owing to the rain. Many motorists had to take shelter at bus stands and under bridges.
A huge tree fell on GST Road near the road overbridge at Tambaram, affecting the movement of vehicles towards Tambaram from Chengalpattu. This resulted in a pile up of vehicles as far as Guduvanchery. Diversion of vehicles through the Chennai Bypass was of little help. After nearly an hour's struggle, the uprooted tree was removed.
Traffic flow on other stretches of the national highway, including in Tambaram Sanatorium and Chromepet, was also hit. Power supply was disrupted as a precautionary measure in many places.
V.Santhanam, a resident of Chromepet, said water entered many houses in Chromepet and Sholavaram Nagar, Pammal, following the heavy showers. Many people bound for Chennai airport had a tough time negotiating traffic.
According to the Meteorological department, Nungambakkam and Meenambakkam registered a maximum temperature of 34.3 degree Celsius and 35.8 degree Celsius respectively on Monday. The maximum temperature normally recorded during this period is 34 degree Celsius.
However, it only drizzled in many localities in the city. While Nungambakkam did not record any rainfall, Meenambakkam recorded 9 mm during the 12-hour period ending 8.30 p.m. Officials of the department said thunder squalls were common during such rainfall. Unlike monsoon rainfall, showers due to convective activity was scattered based on the clouding pattern.Chennai has already received nearly twice the amount of rainfall so far for this season – between June and September. Since June 1 to Monday, the observatory in Nungambakkam recorded 62 cm as against the average rainfall of 34 cm for the season. The facility in Meenambakkam registered 47 cm against the normal of 38 cm.
Y.E.A. Raj, Deputy Director General of Meteorology, Regional Meteorological Centre, said though rainfall during this period is normal, rain at such frequent intervals that has been seen this year is rather unusual.
The convective activity following high temperature during noon is aided by sea breeze, which brings in moisture as it sets in around 3 p.m., results in rainfall.
Normally, depression forms over the Bay of Bengal frequently during this season, providing rainfall to other States. However, this year, there were no depressions that proved favourable to the city, he said.
There has been a rise in annual average rainfall as well, going by the statistics of past four decades from 1969. The annual normal has been increased from 122 cm to 140 cm. In recent years, as in 1996 and 2005, the city had recorded an annual rainfall of over 200 cm, Dr.Raj said.
The department forecasts rain or thundershower would occur in some areas during evening or night for the next two days.
