Cyclone 'Nada' to wind down as deep depression this evening December 01,2016

 Relief to TN, Puducherry as cyclone Nada weakens

Cyclone 'Nada' is forecast to wind down in strength as a deep depression by this evening December 01,2016, while still being based over the water. 

It is forecast to cross the Tamil Nadu coast early tomorrow morning Dec 02,2016

India Met Department (IMD) located 'Nada' to about 330 km south-southeast of Chennai, 270 km southeast of Puducherry and 210 km north-northeast of Trincomalee (Sri Lanka), according to latest available information. 

The system is likely to move west-northwestward to cross the North Tamil Nadu coast between Vedaranniyam and Puducherry, south of Cuddalore. 

The Met has forecast light to moderate rainfall at most places in Tamil Nadu and Puducherry with isolated heavy to very heavy rainfall during the next two days. 

Light to moderate rainfall has also been forecast at many places in Kerala with isolated heavy falls tomorrow and the day after. 

Squally winds speed reaching 45- to 55 km/hr and gusting to 65 km/hr would prevail along and off the Tamil Nadu and Puducherry coasts until tomorrow. 

Sea condition would be rough to very rough these coasts during this period. Fishermen are advised not to venture into sea. 

The weakening of the storm will occur due to high vertical wind shear values, or the speed at which winds change direction with height at a given place

.

This is despite the support 'Nada' enjoys from the ground level (higher sea surface temperatures, which fuels it) and 'window effect' at the top (helping it 'breath out' and in turn draw incremental strength from within). 

But high wind shear values prevent the storm from building in height (of up to 10 to 12 km, depending on size) and lops off the head of the storm tower, undermining its overall strength. 

In addition, the sea waters are cooler towards the coast of Tamil Nadu, which is a disincentive for the cyclone as it hits the home stretch.