Sanjeev Kumar Patro

News Highlights

  • The system will bring rainfall in and around Chennai and other coastal districts of Tamil Nadu and Sri Lanka. The system may also bring a spell of rainfall in Kerala.
  • Analysis of the IITM MME clearly reveals that rain is unlikely in Odisha till the end of April, even as pre-monsoon activities (rainfall of around 5mm/day)witness a kick-start in the neighbouring states like West Bengal and Jharkhand.

Bay of Bengal had given birth to a low pressure system in the first week of March. Keeping the trend, the bay will be hosting a fresh low pressure area over the Andaman seas at night hours on April 5 (April first week).

The area where the low pressure area will take shape has all the elements to nourish the system. The tropical cyclone heat potential is predicted to remain at over 110 kjcm2. While at the place of the genesis of the system, the sea surface temperature is predicted at over 30 deg C, the sea surface temperature of the Bay of Bengal as a whole is predicted to hover between 28 - 32 deg C.

April Showers?

With such favourable indices, will the system grow up to become a cyclonic storm then? Historically verifying, between 1891 and 2021, the month of April had seen a total of 8 cyclones, including one super cyclone.

However, the significant fact here is that none of the systems has formed in the first week of April. Almost all cyclones in April developed after the first fortnight only. A total of two cyclones (Bijli -2009 and Marutha -2017) formed in the second week of April (14-17) could grow up to only category -1 cyclonic storms.

Data with IMD shows that the landfall of both cyclonic storms took place in Bangladesh (near Chittagong) and Myanmar (near Sandoway). And the place of origin has been around the same (Andaman Seas and southeast BoB) region.

April 2022 Story?

Will April 2022 join the years of 2009 and 2017? The history of April is evident that both the cyclones in the first fortnight after the initial westward/northwest track took a recurve towards Myanmar (and Bangladesh).

However, even as the system has all the elements to gain strength, the predicted high wind shear of around 25-30 knots will be going to prove as the major hurdle before the fresh low pressure system's intensification.

As per IMD, INCOIS, NCEP-GFS and ECMWF model analysis, due to high wind shear of over 20 knots, the system is unlikely to grow into a cyclonic system.

The Myanmar Weather Department has today predicted that the system will grow up to become a depression and will chart a westward track.

A study of the wind models of IMD, INCOIS, NCEP-GFS and ECMWF shows that the surface level wind speed of the system will hover between 30-60 km/hr. As a consequence, the analysis reveals that the upcoming low pressure system is unlikely to steam up to a cyclonic system.

However, the system will bring rainfall in and around Chennai and other coastal districts of Tamil Nadu and Sri Lanka. The system may also bring a spell of rainfall in Kerala.

Odisha Impact

Analysis of the IITM MME clearly reveals that rain is unlikely in Odisha till the end of April, even as pre-monsoon activities (rainfall of around 5mm/day) witness a kick-start in the neighbouring states like West Bengal and Jharkhand in the second fortnight of the month.

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