The Hindu Business Line : Wet spell on as ‘low’ gets pushed by a day

Thiruvananthapuram, Nov. 23 A prevailing easterly wave helped sustain active northeast monsoon conditions over Tamil Nadu and parts of the southern peninsula even as the watch for a low-pressure in the Bay of Bengal area was maintained.

India Meteorological Department (IMD) said in its outlook on Sunday that the ‘low’ watch was being pushed by another day to November 27 (Thursday). It expected the system to get a move to the west-northwest.

The Global Forecast System model of the US Fleet Numerical Meteorology and Oceanography Centre saw the ‘low’ intensifying into a cyclone and hitting the southern Tamil Nadu-north Sri Lanka belt around November 30.

OPINIONS VARY

Unlike the IMD, the US model doesn’t show marked west-northwest movement of the system, but takes it along a less pronounced incline aiming to hit the south Tamil Nadu. In doing so, it would adhere to the pattern conventionally identified with an easterly wave – fast in lateral movement and straight in direction.

This is exactly what has led forecasters here to doubt whether the wave would get the time and space to intensify rapidly to become a cyclone while not denying that easterly waves have in the past gone on to become just that, especially during the month of November.

Another US-based forecaster, the Centre for Ocean-Land-Atmosphere Studies, had predicted in initial model runs that the brewing system in the Bay might take a west-northwest course and head for the Andhra Pradesh-Orissa coasts.

ACTIVE MONSOON

Meanwhile, the Chennai Met Centre said in its update that the State of Tamil Nadu, especially the coastal regions, witnessed active monsoon conditions during the 24 hours ending Sunday morning.

Rainfall occurred at most places over coastal Tamil Nadu, at many places in the interior and at a few places over Rayalaseema, Kerala and south interior Karnataka. Isolated rainfall occurred over coastal Andhra Pradesh, Telangana, coastal Karnataka and Lakshadweep.

A rain-driving cyclonic circulation over the southwest Bay off south Tamil Nadu-Sri Lanka coasts persisted from overnight. Model runs by the National Oceanic and Atmosphere Administration of the US suggested that it would move west-northwest and cross into south Kerala, before sliding into the Arabian Sea.

BETTER CONVERGENCE

The parent trough of low (hosting the cyclonic circulation) covered the southwest and adjoining southeast Bay on Sunday. Coastal Tamil Nadu is tipped to witness increasing convergence of moisture-laden easterlies over the next few days.

This would keep the prevailing wet weather going until Thursday when the ‘low’ is expected to materialise over the southeast Bay.

Outlook for the next two days aid rain or thundershowers are likely to occur at most places over coastal Tamil Nadu and Puducherry and at many places over interior Tamil Nadu, south Kerala and south coastal Andhra Pradesh and at a few places over North Kerala, Rayalaseema, south interior Karnataka and Lakshadweep.

Isolated rain or thundershowers are likely to occur over Telangana, north coastal Andhra Pradesh, coastal and north interior Karnataka.

A separate warning spoke of the possibility of isolated heavy to very heavy rain over coastal Tamil Nadu and Puducherry during the next two days. Isolated heavy rain is likely over interior Tamil Nadu and south Kerala during the same period.

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