Northeast monsoon: Chennai braces for more rain as IMD declares Orange alert

IMD maintains a network of Automatic Weather Stations (AWS) and Automatic Rain Gauge (ARG) stations across the State to measure rainfall on a real-time basis.

Students walking through slushy playground of Corporation High School at Vyasarpadi on Wednesday | DEBADATTA MALLICK

CHENNAI: Even as India Meteorological Department (IMD) announced the onset of the northeast monsoon on Wednesday with an ‘Orange alert,’ which means ‘Be Prepared,’ over 50 of its weather stations which record rainfall in the State are reportedly not working or functioning properly.

IMD maintains a network of Automatic Weather Stations (AWS) and Automatic Rain Gauge (ARG) stations across the State to measure rainfall on a real-time basis. The data generated helps administrators in staying prepared for the monsoon and in disaster management.

However, sources told Express the 51 stations have been malfunctioning for several days due to improper maintenance. Of them, 12 are AWSs and 39 are ARGs. Taramani ARG in Chennai is one of the systems that went rogue. S Balachandran, Deputy Director-General of Meteorology,  Regional Meteorological Centre, said there were technical issues with a few weather stations in the State and the matter was raised with the headquarters. “A few spares have to be replaced and they have to come from Pune. Efforts are being taken to address it.”

Interestingly, maximum faulty stations are located in and around Chennai. ARG stations at  Taramani, Avadi, Poonamallee, Puzhal, RK Pet and Kattupakkam are not reporting any data.  Monsoon rain has already started lashing Chennai and suburbs. In the last 24 hours ending 8.30 am on Wednesday, Poonamallee received highest rainfall in the State recording 11 cm. In the absence of ARG, authorities have to depend on standard rain gauge in which reading is taken manually only the next morning.
J Radhakrishnan, Commissioner of Revenue Administration, Disaster Management and Mitigation, said he would take up the matter with IMD.      

As per National Disaster Management Authority guidelines prepared in 2010', there should one ARG for every four sq km. Chennai core area, which is about 176 sq km, requires at least 44 ARGs. The document said lack of spatial and temporal rainfall data over urban areas on a real-time basis is a critical gap.
Mrutyunjay Mohapatra, Director-General of Meteorology, IMD, told Express, "Yes, Chennai does not have enough stations. We have plans to enhance it by another 30s."

Early arrival

• Southwest monsoon has withdrawn from the entire country. Northeast monsoon rain has commenced over Tamil Nadu, AP, Karnataka and Kerala.
   
• Retreat of southwest monsoon is one of the fastest realised in recent years.
   
• IMD has announced that northeast monsoon arrival has advanced by a day.   
   
• According to S Balachandran, DDGM, Kanniyakumari, Tirunelveli, Thoothukudi, Ramanathapuram, Tiruvallur, Kancheepuram, Cuddalore and Cauvery delta districts will receive heavy rain till Thursday.
   
• NE monsoon accounts for about 48 per cent of Tamil Nadu’s annual rainfall of around 945 mm and stretches till December.
   
• Fishermen have been advised against venturing into sea in Kanniyakumari on October 17 and 18.
   
• In Chennai, the sky is likely to be cloudy. One or two spells of rain or thundershowers is likely to occur.