As expected, a persisting low-pressure area over the South Andaman Sea and the adjoining South-East Bay of Bengal has weakened and is likely fading out. Only a remnant cyclonic circulation lingered on Wednesday, more or less bringing to closure a prolonged wait for a previously expected pre-monsoon storm here.

On Wednesday morning, the India Meteorological Department (IMD) spotted scattered to broken low and medium clouds with embedded moderate to intense convection over the South-East Bay. Interestingly, scattered low and medium clouds with embedded moderate to intense convection hovered also over the South-East Arabian Sea (around the Kerala coast) to the other side of the peninsula.

No model consensus

Global and domestic weather models are employing different methods to arrive at a consensus with respect to the evolving weather over the Bay. The European Centre for Medium-Range Weather Forecasts (ECMWF) persists with its prediction of fresh cyclogenesis (birth of a circulation) over the South-East Bay, not too far away from where the extant low-pressure area is fading out.

Latest ECMWF model runs indicated that the cyclogenesis might take place around May 13 and the system may move to the West-North-West into the open waters of the Bay the next day. The IMD’s Genesis Potential Parameter index forecast sees a potential zone of cyclogenesis not just over the South Andaman Sea during the two next days (May 6-8), but also another over the South-West Bay (closer to Sri Lanka and Tamil Nadu coast) and a movement to the North (May 7-12).

The IMD-GFS (Global Forecast System) sees potential cyclogenesis around May 15 with intensification and tracking of the system to the North. Meanwhile, satellites picked winds speeding up to strength of 28 km/hr over South Andaman Sea on Tuesday. The IMD summarised that environmental features indicate further weakening of the current system over the South Andaman Sea and that most other models do not predict any cyclogenesis over the Bay at least until May 11.

Delayed heat wave

Heat wave conditions are getting established with some delay, thanks to a surplus run of the pre-monsoon thunderstorms in many parts of the country. In the short-term, Vidarbha (next two days) and West Rajasthan during (Friday and Saturday) will get impacted. Maximum temperatures may remain at 41-43 degrees Celsius over parts of Telangana, Rayalaseema and North Interior Karnataka; at 41-44 degrees Celsius over Madhya Maharashtra, Marathwada and Vidarbha; and at 40-41 degrees Celsius over interior Tamil Nadu during the next two days.

Incoming moisture mopped up winds from the Bay and supporting upper atmospheric features will trigger fairly widespread to widespread rain/thundershowers over North-East India and scattered to fairly widespread over East India during the next 2-3 days. Confluence between westerlies and moist easterlies may drop scattered to fairly widespread rain/thundershowers over the hills of North-West India.

It will be isolated to scattered over the adjoining plains in the North-West until Thursday. Thunderstorms accompanied with lightning, gusty winds/squalls and hailstorm are likely to lash these regions. Isolated to scattered rain/thundershowers are forecast over parts of Central and South Peninsular India during the next 4-5 days. Thunderstorms accompanied with lightning and gusty winds (30-40 km/hr) are also likely over parts of these regions.

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