Rare February system likely to bring heavy rain to parts of south T.N. on February 21 and 22

The Bay of Bengal has witnessed only five weather systems that intensified into a depression in February since 1891. This year’s February low-pressure area is expected to become more marked and could bring isolated heavy rainfall to parts of southern Tamil Nadu on February 21 and 22.

The low-pressure area that has formed over east equatorial Indian Ocean and the adjoining central parts of south Bay of Bengal is likely to become more marked over southwest Bay of Bengal and the adjoining east equatorial Indian Ocean by February 18.

Citing records of cyclones and depression tracks, B. Amudha, Head, Regional Meteorological Centre (RMC), said the most recent weather systems during February were seen in 1961, 1999, and 2011. However, none of these further developed into a cyclone.

February typically records very few rainy days and low rainfall totals across many districts. For instance, in Kanniyakumari district, the average February rainfall is only 7.9 mm, with a normal of just 0.7 rainy day during the month. Similarly, Nagapattinam district gets an average rainfall of 13 mm, with a normal of 0.8 day. Nungambakkam in Chennai too receives normal rainfall of 5.5 mm, with only half a rainy day. However, there have been occasions when these districts recorded more than their average rainfall during this period.

Officials of the India Meteorological Department (IMD), New Delhi, said while the formation of a low-pressure area in February was not uncommon, the weather system intensifying into a depression was rare and such systems largely impacted Sri Lanka. Large scale atmospheric features, including Madden-Julian Oscillation, can also influence cloud cover and rainfall in the south Bay of Bengal and east Equatorial Indian Ocean. The current February system is likely to bring rainfall over Sri Lanka and parts of Tamil Nadu and Kerala, officials said.

V.R. Durai, Director, Area Cyclone Warning Centre, RMC, Chennai, said a strong temperature anomaly persisted in the east equatorial Indian Ocean. Warm sea surface temperature in the region this time had favoured formation of a low-pressure area. However, the system is being monitored for further intensification. The RMC has forecast a possibility of wet spell in south-coastal Tamil Nadu and delta districts between February 19 and 22. “We have predicted isolated heavy rainfall in some delta and south Tamil Nadu districts, going by the weather models,” Mr. Durai added.