The Hindu Business Line : Cyclonic pattern under close watch: Met Office

THE upper air cyclonic circulation that triggered widespread rain/thundershowers in parts of Coastal Andhra Pradesh, Tamil Nadu and Kerala could well be the precursor to the southwest monsoon, if last year's trend is any indication.

Mr M. D. Ramachandran, Director, Met Office, Thiruvananthapuram, told Business Line that the respective run-ups to the `big climatologic event' of the year provides for striking comparison.

Last May, the country experienced two major weather disturbances - the cyclonic circulations on May 1 and 19. The latter one pulled off a coup of sorts by drawing in the advancing monsoon currents, dumping rain on the southwest coast and bringing about an early onset in Kerala.

This time round, upper air cyclonic circulation has more or less kept date, with a lag of only one day compared to the last year. According to Mr Ramachandran, the Met Office is closely watching the system since any descent to the surface level could mean its conversion into a low-pressure area.

While the official long-range India Meteorological Department (IMD) forecast has indicated a `normal' monsoon this year, sufficient hints have been dropped to the effect that the onset could be earlier this year, too. The Bangalore-based Centre for Mathematical Modelling and Computer Simulation (C-MMACS) has taken a call in this regard saying the onset could happen as early as May 26.

During the 24 hours ending at 8.30 a.m. on Monday, rainfall occurred at many places over Coastal Andhra Pradesh and at a few places over Tamil Nadu, Telengana, Rayalaseema, Karnataka, Kerala and Lakshadweep.

The maximum rainfall of eight cm each was recorded at Cheyyar and Polur in Tamil Nadu. Forecast valid till Wednesday said rain or thundershowers are likely to occur at a few places over Tamil Nadu, Pondicherry and Coastal Andhra Pradesh.

Isolated rain or thundershowers are likely to occur over Telengana, Rayalaseema, South Interior Karnataka and Kerala. Mainly dry weather will prevail over Coastal and North Interior Karnataka and Lakshadweep.

Kerala weather

According to the Agromet Bulletin issued by the Met Office, Thiruvananthapuram, rain or thundershowers occurred at isolated places in the State during the three days ending May 1.

The chief amounts of rainfall in cm are (April 28 to May 1):

April 28: Ambalavayal - 3 and Kuppady - 1.

April 29: Kuppady - 5; Chengannur - 3; Munnar - 2 and Devikolam - 1.

May 1: Munnar - 4; Kollam - 3 and Punalur and Kollengode - 1 each.

Mean maximum temperature varied between 34°C and 35°C in various districts. Kannur recorded the highest maximum temperature of 35.4°C on May 1.

The highest maximum temperature was 3°C above normal in Thiruvananthapuram district on April 29 and May 1.

Mean relative humidity varied between 64 per cent and 81 per cent in various districts, mean cloud coverage between one okta and five okta and mean wind speed, two kmph and 10 kmph.

Forecast valid until the morning of Wednesday spoke about the possibility of rain or thundershowers at a few places in all districts of the State. Outlook for the two subsequent days did not indicate any change.

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