The Hindu Business Line : Easterly wave tightens grip over peninsular weather

Thiruvananthapuram, Nov. 20 Active northeast monsoon conditions prevailed over coastal Tamil Nadu on Thursday as an itinerant easterly wave firmed up its grip over peninsular weather. The wet weather over the peninsula may hold for another four to five days.

There is growing model consensus over a likely cyclone brewing off the Tamil Nadu coast towards the month-end but they differed in the choice of a projected area for landfall.

On Thursday, the European Centre for Medium-Range Weather Forecasts (ECMWF) retained its outlook for the event while model runs at the US-based Centre for Ocean-Land-Atmosphere Studies (COLA) and the Fleet Numerical Meteorology and Oceanography Centre (FNMOC) seemed to concur.

The FNMOC runs two models – Navy Operational Global Atmospheric Prediction System (NOGAPS) and Global Forecast System (GFS). Of this, NOGAPS gave out a resounding endorsement of the ECMWF outlook.

It saw converging winds around a building weather system in the central Bay of Bengal speeding up to 30-35 knots (56-65 km/hour) on November 26-27. This is just a churn away from being classified as a cyclone, but these are initial days yet to take a call, according to forecasters.

LANDFALL AREA

The ECMWF model took the storm straight into the Tamil Nadu coast, but COLA sees the system veering to west-northwest and aiming to hit the Andhra Pradesh-Orissa coasts. On Thursday, FNMOC model forecasts were available up to November 27 only and did not suggest indicative landfall co-ordinates.

An India Meteorological Department (IMD) update said that an expectant trough of low-pressure persisted from overnight over the southeast Bay. So too, did the cyclonic circulation over southwest Bay off the south Tamil Nadu-Sri Lanka coasts, as easterlies-to-northeasterlies firmly established their presence across the peninsula.

IN TANDEM

According to consensus ‘cyclone evolution phase’ analysis, the southwest Bay system is acting in tandem with the easterly wave to extend the rain cover to Sri Lanka and later west-northwest to extreme south peninsular India (south Kerala and neighbourhood).

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