A layer of smog hovered over the city in the early hours of Wednesday due to Bhogi celebrations. However, cloudy skies and strong north easterlies helped improve visibility, early, in many areas, according to the Meteorological Department.
While shallow fog was observed for a short period between 7.10 a.m. and 8 a.m., the horizontal visibility, reported over the Chennai airport, Meenambakkam, was up to 1,000 m, on Wednesday, unlike the previous years, when visibility in the early morning of Bhogi would drop to even 50 m.
Officials of the Department said normally, clear skies during the night, in January, helped in the formation of radiation fog. However, this time, cloudy skies prevented dense fog.
B. Amudha, scientist-E and in-charge of the Aerodrome Meteorological Office, Meenambakkam, said the horizontal visibility, observed through polar diagrams for the Chennai airport, between 7 a.m. and 8 a.m., was 1,000 m. Visibility improved after 8 a.m.
“This year, calm winds prevailed only for a short duration, between 2 a.m. and 6 a.m. on Wednesday, and strong north easterlies, due to the Northeast monsoon spillover, kept night temperatures on the warmer side, at 25 degrees Celsius in Meenambakkam. Winds also helped dissipate mist quicker,” she said.
On January 14 (Bhogi) last year, westerly winds brought smoke from inland to the airport region, during the early morning hours. Visibility reduced to the lowest, at 150 m, at 7.15 a.m., and improved to 800 m, only at 9 a.m., she recalled.
The Department has also forecast that wet weather, over south coastal areas and places along the Western Ghats, is likely to prevail till January 16. A trough of low running from Comorin-Maldives area to the Lakshadweep area, with an embedded cyclonic circulation, triggered the rain. However, intense rain may ease out, and dry weather may return from Sunday. In the last 24 hours, ending 8.30 a.m. on Wednesday, Parangipettai in Cuddalore district recorded heavy rain of 28 cm. Rainfall continued over districts such as Tirunelveli, Thoothukudi, Thenkasi and Nagapattinam on Wednesday too.
N. Puviarasan, director, Area Cyclone Warning Centre, Chennai, said light to moderate rain was likely to occur over south coastal and delta districts and areas along the Western Ghats, till Friday. The withdrawal of the Northeast monsoon would be declared only after dry weather sets in, he said.
This month will be one of the wettest January for the State. All districts have received excess rainfallwith their deviation percentage running in hundreds. Tamil Nadu, so far, has received an average of 11 cm of rain, which is 966% more than its monthly share.
To encourage people’s participation, the Department has launched a crowdsourcing interface on its website, wherein citizens are asked to share details about weather events and their impact in their region. “This will help in data collection and to improve weather forecast,” he said.
