North-east monsoon to be normal, La Nina to remain neutral: IMD
New Delhi: Southern peninsular India will receive normal rainfall during the October to December north-east monsoon season, which accounts for 30% of the region’s annual rainfall, the India Meteorological Department (IMD) said.
In an operational forecast, the IMD said rainfall during the 2016 north-east monsoon is most likely to be normal or 90-00% of the long period average (LPA) and that rainfall over Tamil Nadu is similarly likely to be normal.
The north-east monsoon is particularly important for Tamil Nadu, which receives 48% of its annual rainfall during the season. The southern peninsular region consists of five subdivisions: Tamil Nadu, coastal Andhra Pradesh, Rayalaseema, Kerala and south interior Karnataka.
The currently weak La Nina conditions over equatorial east Pacific will turn to cool neutral conditions during the north-east monsoon season, according to IMD. La Nina is an ocean-cooling weather phenomenon that causes heavy rain in India.
The weather forecaster also said the current weak negative Indian Ocean Dipole (IOD ) conditions are likely to continue during the north-east monsoon season. A positive Indian Ocean Dipole is associated with more rainfall in the country.
IOD refers to the difference in surface temperatures between the western and eastern parts of the sea. Negative IOD is characterized by warmer than normal sea surface temperature in eastern Indian Ocean and cooler than normal sea surface temperature in the western part.
“Neutral La Nina and negative Indian Ocean Dipole will play an important role during this north east monsoon season,” said D.S. Pai, head of long-range forecasting at IMD.
Last year, IMD had forecast above normal north-east monsoon—111% of its LPA for the region and 112% of the LPA for Tamil Nadu.
The actual rainfall over the south peninsula was 132% of its LPA and 152% of the LPA over Tamil Nadu.