Poor monsoon leaves city with 54% deficit
U.Tejonmayam@timesgroup.com
Chennai:18.121.2018
The city is staring at a huge rain deficit of 54% with just 13 days left for the northeast monsoon season to end officially. Chennai has got 343.4mm rain since October 1, against the expected 747.1mm.
However, expect a bit of rain over the weekend after a dry spell for the next three days. This is because the energy left in the ocean and the atmosphere after cyclone Phethai, as a trough or low atmospheric pressure over an elongated region, could help.
“It’s called easterly wave, but it’s not a strong system like a low pressure or depression or a cyclone that brings very heavy rainfall. It will, however, give sustained rainfall over two or three days, which may bring 80mm-100mm and cut the deficit. But we will still be looking at a 40% deficit,” said Prof Sridhar Balasubramaniam, a climate expert from IIT Bombay.
Experts said such a trough is a common phenomenon after a tropical cyclone hits the coast. As the Bay of Bengal retains enough moisture after a cyclone, and the temperature over the sea is also higher, it leads to a convection process.
“Chennai received rainfall in the last week of November, a few days after Gaja, which was due to an easterly wave. This weekend too, Chennai will see a similar system,” Balasubramanian said. For the next three days, the city will have dry weather.
Cheer as rain forecast for city this weekend
IMD deputy director-general S Balachandran said, “There may be some rainfall at the end of this week. But we have to wait and see.”
The regional meteorological centre faltered twice in predicting the onset of the northeast monsoon. The first announcement with a red alert on October 7 and triggered a scare before private weather bloggers allayed fears of heavy rain. The city did not get rain and the met officials retracted the red alert and said that the monsoon did not set in because of a change in wind direction. The met department later said that the monsoon would set in around October 26.
When cyclone Gaja was first forecast to cross between Cuddalore and Chennai, there were hopes of rain for the city. However, the cyclone shifted course and Chennai missed rain.
With Phethai too there were hopes of rain for Chennai. “The outer band of the system was only 40km from Chennai before it moved northwards to the Andhra coast. We expected that band to touch north coastal Tamil Nadu and bring rains,” said Pradeep John, weather blogger.
In 2017, the city had recorded 554.2mm rain in November first week itself. It was 74% of the long term average of 750mm rain received annually from the rainy season.
HOPES HIGH
U.Tejonmayam@timesgroup.com
Chennai:18.121.2018
The city is staring at a huge rain deficit of 54% with just 13 days left for the northeast monsoon season to end officially. Chennai has got 343.4mm rain since October 1, against the expected 747.1mm.
However, expect a bit of rain over the weekend after a dry spell for the next three days. This is because the energy left in the ocean and the atmosphere after cyclone Phethai, as a trough or low atmospheric pressure over an elongated region, could help.
“It’s called easterly wave, but it’s not a strong system like a low pressure or depression or a cyclone that brings very heavy rainfall. It will, however, give sustained rainfall over two or three days, which may bring 80mm-100mm and cut the deficit. But we will still be looking at a 40% deficit,” said Prof Sridhar Balasubramaniam, a climate expert from IIT Bombay.
Experts said such a trough is a common phenomenon after a tropical cyclone hits the coast. As the Bay of Bengal retains enough moisture after a cyclone, and the temperature over the sea is also higher, it leads to a convection process.
“Chennai received rainfall in the last week of November, a few days after Gaja, which was due to an easterly wave. This weekend too, Chennai will see a similar system,” Balasubramanian said. For the next three days, the city will have dry weather.
Cheer as rain forecast for city this weekend
IMD deputy director-general S Balachandran said, “There may be some rainfall at the end of this week. But we have to wait and see.”
The regional meteorological centre faltered twice in predicting the onset of the northeast monsoon. The first announcement with a red alert on October 7 and triggered a scare before private weather bloggers allayed fears of heavy rain. The city did not get rain and the met officials retracted the red alert and said that the monsoon did not set in because of a change in wind direction. The met department later said that the monsoon would set in around October 26.
When cyclone Gaja was first forecast to cross between Cuddalore and Chennai, there were hopes of rain for the city. However, the cyclone shifted course and Chennai missed rain.
With Phethai too there were hopes of rain for Chennai. “The outer band of the system was only 40km from Chennai before it moved northwards to the Andhra coast. We expected that band to touch north coastal Tamil Nadu and bring rains,” said Pradeep John, weather blogger.
In 2017, the city had recorded 554.2mm rain in November first week itself. It was 74% of the long term average of 750mm rain received annually from the rainy season.
HOPES HIGH
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