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Sanjeev Kumar Patro

Bhubaneswar: Already grappling with the COVID menace imported from overseas, the country is keenly watching at the development of another danger brewing in the seas this time. And which coincidentally shares the same initial 'C'  - the 'Cyclone' in the Andaman seas.

This cyclone seems not in a hurry. Many international Met models predict it to acquire the stature of a very severe cyclonic storm. And the latest prediction is the developing cyclone will make landfall on around May 13-14.

As per the Regional Specialised Meteorological Centre - Tropical Cyclones, New Delhi,  a Low Pressure Area (LOPAR) over the south Andaman sea and the adjoining South east Bay of Bengal has been identified on May 1. The prediction is its intensification is likely to get further delayed owing to pronounced diurnal variation in convection and slight increase in vertical wind shear over the region.

What seems impeding the faster brewing of the system into a tropical cyclone is the pronounced variation in the maximum daytime and minimum night time temperature in the region. Moreover, a tad higher vertical wind shear is preventing its updraft. The result is the cyclonegenesis is taking more time to develop into a cyclonic storm.

Will the LOPAR dissipate then?

Seems very unlikely. Weathermen say the cyclonegenesis will start on May 7, when the LOPAR will become well marked.  And within 24 hours after May 7, it will develop into a tropical depression.

The Reason: MJO (Madden Julian Oscillation) phase will support enhancement of convective activity over Bay of Bengal during next 2-days. Moreover, the minimum cloud top temperature recorded stood at (-) 90 degree Celsius. This shows the cloud top temperature is nearly uber cool, which will greatly assist in updraft activity of the LOPAR.

Satellite pictures show broken, low and medium clouds embedded with intense to very intense convection (see the image above).

This condition facilitates heat transfer, a condition vital for cyclonegensis. Also the sea surface temperature in the BoB region is around 30-31 degree C, far higher than normal sea surface temperature of 28 deg C during summer.

What Met Models Say?

As per the ECMWF (European Center for Medium Range Weather Forecast), the LOPAR will develop into a very severe cyclonic storm. The system will first move towards north Andhra - south Odisha (see the image below) due to the effect of easterly winds.

[caption id="attachment_448893" align="alignnone" width="650"]Track of Cyclone Amphan Left to right: 1) Formation of depression, 2) Movement towards Indian coasts 3) Landfall in Myanmar[/caption]

Later, will deflect towards the north and further bend eastwards to make landfall in Myanmar on May 13.

US-based GFS: Model of this ace Met agency is in unanimity with the ECMWF model. It says after initially veering towards Andhra-Odisha coasts, will recurve towards Myanmar to make landfall on May 13. (see the image below)

[caption id="attachment_448894" align="aligncenter" width="650"]Cyclone Amphan track forecast by US-GFS Left to Right: 1) Cyclone Amphan veering towards Indian coasts 2) Making Landfall in Myanmar[/caption]

Indian Cyclone Watch Agencies: Models of Indian Institute of Tropical Meteorology, Pune and NCMRWF (National Centre for Medium Range Weather Forecasting) are in unanimity with the ECMWF and US-GFS. The models show it will veer towards Indian coasts (north Andhra-south Odisha) initially (May 12), and then move towards north and north east to make landfall in Myanmar on around May 13.  

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