Sanjeev Kumar Patro

Bhubaneswar: Is a Low Pressure Area (LOPAR) likely to develop over the Andaman sea on November 4 later progress into a cyclone in Bay of Bengal (BoB)?

Significantly, October - November period has been the cyclone season in BoB. But post brewing up Fani in May this year, the BoB has been relatively quieter this year till date, when the usually cooler Arabian Sea has brewed up two cyclones - Kyarr and Maha -  in succession.

However, the models of INCOIS (Indian National Centre for Ocean Information Services), under Ministry of Earth Sciences, indicate the LOPAR system developing by November 4 over Andaman Sea will be later graduating into a deep depression by November 6.

Though the IMD in its last weather inference, didn't mention about any cyclone genesis, it made a forecast about formation of a LOPAR over north Andaman sea and adjoining south-east Bay of Bengal by November 4.

As the weather inferences show prevalence of the factors responsible for cyclone genesis in the Bay of Bengal, there is high probability of the LOPAR later developing into a depression and then intensifying further into a cyclonic storm by November 8.

The Bay of Bengal’s surface temperature at the LOPAR region is now hovering at over 31 – 32 degree Celsius, which is abnormally higher than the normal sea surface temperature during October.

Moreover, the model shows the sustaining wind velocity would be around 35km/hr by November 6. Along with blowing of easterly winds, as suggested by the models, and the wind direction predicted at around 82 – 90 degrees from north, the conditions seem favourable for developing of the LOPAR into a depression by November 6.

The persistence of the conditions beyond November 6 is likely to aid the system to graduate into a probable cyclonic system.

But the big question then is will the system move towards Odisha coast?

An analysis of sea surface temperature (SST) around Odisha coast predict the SST to hover at around 26 degrees Celsius. This reveals the coast adjoining to landmass of Odisha has relatively lower atmospheric pressure. Since cyclones are systems that move from low to high pressure fronts, the system may not veer towards Odisha coast.

However, as vertical wind shear plays a crucial role in cyclonic system's likely path, the forecast made about the wind direction near Odisha coast will be around 87-88 degrees C, which means they are vertical.

This is a bad news, because vertical winds play an important role in sustaining a cyclonic storm and influencing its movement too.

However, as most cyclones follow a linear path, the models suggest that the probable path of the ‘possible cyclonic storm’ will be between Srikakulum and Visakhapatnam coast.