• Investment World
• eWorld
• Brand Line
• Mentor
• Life
• Brand Quest
• The New Manager
• BL Club
• Smartbuy

Stocks

• Quotes
• SE Diary
• Scoreboard
• Open-End Mutual Fund

Cross Currency

• Rates
  
  

Shipping

• Ports
  
  

Archives

• Yesterday
• Datewise
• Resources
• In Focus
• In Depth
• Events 2007

Group Sites

• The Hindu
• The Hindu ePaper
• Business Line
• Business Line ePaper
• Sportstar
• Frontline
• The Hindu eBooks
• The Hindu Images

Vinson Kurian

Thiruvananthapuram, Nov. 26 Tuesday’s well-marked ‘low’ over southwest Bay of Bengal underwent three rounds of intensification in rapid succession to become Tropical Cyclone Nisha on Wednesday.

The system has tracked a northwesterly course to approach the Tamil Nadu coast near Vedaranniyam. Its behaviour was being watched with interest given the proximity to land and, more important, the distance `it did not’ travel over water.

These factors were seen as not aiding the evolution of Nisha as a storm, but what apparently did is her extended stay over the water – being too slow in lateral movement, even stubbornly so at times. This was evidenced in the manner in which the entourage dropped anchor off Vedaranniyam since Wednesday afternoon.

This extended stay allowed the system to feed further on the moisture available – piped in from as far away as the southwest Indian Ocean off the Horn of Africa – and kick up convection to sustain its bearings, if not build further on them altogether.

Landfall instantaneously cuts off the warmth of the sea surface, which helps fuel convection; the moisture feed is compromised, too. This leads to rapid weakening of the system, although pre-existing flooded surfaces have been known to aid convection to a limited extent over land.

The Joint Typhoon Warning Centre of the US Military had said in its outlook on Tuesday that it expected the cyclone to cross India’s southeast coast by Thursday.

The Regional Met Centre, Chennai, said in its update that Nisha helped ramp up the northeast monsoon over Tamil Nadu and adjoining regions in the south peninsula. Most places in Tamil Nadu, pronouncedly towards the coast, received very to very heavy rainfall during the 24 hours ending Wednesday morning. It was isolated over coastal Andhra Pradesh, Rayalaseema, Kerala and Lakshadweep.

Forecast for the next two days said most places in Tamil Nadu and Puducherry would witness rainfall with heavy to very heavy falls at a few places. Isolated extremely heavy falls (above 25 cm) are likely during the next 24 hours. Many places over Kerala, south interior Karnataka and Lakshadweep also would come under the heavy to very heavy rain belt.

Gale winds reaching up to 65-75 to 85 km/hr are likely along and off the Tamil Nadu and Puducherry coasts during the next 12 hours. The sea condition would be ‘high’ along and off these coasts.

Extended forecasts until December 1 said that the enhanced rainfall activity is likely to continue over the south peninsula. Isolated to scattered rain is likely over Marathawada, Madhya Maharashtra, Konkan and Goa.

Forecasts by the Joint typhoon Warning Centre of the US indicated that Nisha would continue to track west-northwest after crossing coast, weaken thereafter and wade into Karnataka. Later, it would slide into the Arabian Sea where it would be put under watch for regeneration.

Convection is concentrated more to the northern flanks of a cyclone during a northeast monsoon and this would drive rains into south coastal Andhra Pradesh and adjoining Maharashtra as well.

Rain or thundershowers have been forecast at many places over south coastal Andhra Pradesh, Rayalaseema, south interior Karnataka, Kerala and Lakshadweep and at a few places over north coastal Andhra Pradesh.

Isolated rain or thundershowers are likely over Telangana, coastal and north interior Karnataka.

More Stories on : Climate & Weather | Climate & Weather

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page

Copyright © 2008, The Hindu Business Line. Republication or redissemination of the contents of this screen are expressly prohibited without the written consent of The Hindu Business Line