Severe cyclonic storm Nivar is likely to cross the Tamil Nadu coast between Karaikal and Mamallapuram of the southern state on Wednesday. Nivar, the first cyclonic storm to impact the Indian coast this season will have a wind speed of 100 to 110kmph gusting to 120kmph and bring extremely heavy rain to Tamil Nadu and Puducherry on Wednesday and Thursday.

The weather bureau has said that the depression over southwest and adjoining the southeast Bay of Bengal has moved west-northwestwards and lay centred about 520km east-southeast of Puducherry and 560km southeast of Chennai. M Mohapatra, India Meteorological Department’s (IMD’s) director general, said on Monday that Nivar is very likely to intensify into a cyclonic storm during the next 24 hours.

Officials have said that Nivar is an Iranian name and comes from a list of names suggested by the 13 north Indian ocean countries affected by cyclones in the region.

Here is what to expect under the influence of Nivar:

1. Widespread rainfall and thunderstorm activity over Tamil Nadu, Puducherry and Karaikal are likely from Tuesday to Thursday and over south coastal Andhra Pradesh, Rayalseema and Telangana during Wednesday and Thursday.

2. Extremely heavy rainfall activity also very likely over Tamil Nadu and Puducherry on Tuesday and Wednesday, over south coastal Andhra Pradesh and over Rayalseema on Wednesday and Thursday and over Telangana on Thursday.

3. Wind speed of 55-65kmph gusting to 75kmph is prevailing over southwest and adjoining the southeast Bay of Bengal. It would increase gradually becoming 65-75kmph gusting to 85kmph over the southwest and adjoining west central Bay of Bengal from Tuesday morning. It would further increase becoming 100-110kmph gusting to 120kmph over the southwest Bay of Bengal from Wednesday morning for subsequent 12 hours.

4. Squally wind speed reaching 45-55kmph gusting to 65kmph would prevail along and off Tamil Nadu and Puducherry and adjoining south Andhra Pradesh coast and over the Gulf of Mannar from Tuesday morning. It will gradually increase and become 100-110kmph gusting to 120kmph along and off coastal districts of north Tamil Nadu and Puducherry (Nagapattinam, Karaikal, Myladuthurai, Cuddalore, Puducherry, Villupuram and Chengalpattu districts), 80-90 gusting to 100kmph very likely over Tiruvarur, Kanchipuram, Chennai, Tiruvallaur districts from Wednesday forenoon for

subsequent 12 hours.

5. Gale wind speed reaching 65-75kmph gusting to 85kmph very likely over adjoining the west-central Bay of Bengal and along and off south Andhra Pradesh’s Nellore and Chittoor districts, Gulf of Mannar

and along and off districts of south coastal districts of Tamil Nadu from Wednesday morning for subsequent 12 hours.

6. Sea conditions are likely to be ‘high’ to ‘very high’, with waves of 6 to 14 metres, along the coasts of Tamil Nadu and Puducherry on Wednesday. Tidal wave of one-metre height above the astronomical tide is also expected on Wednesday during landfall.

7. Fishermen have been asked not to venture into southwest and adjoining west-central and southeast Bay of Bengal, Gulf of Mannar and along and off Tamil Nadu, Puducherry and south Andhra Pradesh coasts from Monday to Tuesday. Those out at the sea have been asked to return to the coast and avoid these sea areas.

8. The weather bureau has warned of major damage to thatched houses or huts with the possibility of rooftops being blown off and unattached metal sheets flying. There could be damage to power and communication lines, it added. There could be major damage to paved and some damage to unpaved roads and flooding of escape routes. Tree branches could break and large avenue trees could be uprooted. There could be severe damage to banana and papaya trees, horticulture and crops and orchards and major damage to coastal crops and to embankments and salt pans, it has said.