PEOPLE should brace for heavy showers and thunderstorms due to hit Trinidad and Tobago on Wednesday evening/Thursday morning as part of a tropical wave moving in from the Atlantic Ocean, according to the Met Office.
Meteorologist Stefan Dickson told Newsday on Tuesday that despite uncertainty as to how the disturbance might develop, it TT was virtually certain to face stormy weather.
The Caribbean has just faced Hurricane Fiona, which knocked out the Dominican Republic's power grid, brought heavy flooding to Puerto Rico, and damaged roads, homes and bridges in Guadeloupe, for which the French Government promised assistance.
The Met Office posted an adverse weather alert (yellow level) after lunchtime on Tuesday to last from Wednesday at 5 am to Thursday at 8 pm.
It said, "Showers and isolated thunderstorms, at times heavy, are expected from Wednesday morning over oceanic waters and extending across TT."
This activity is associated with an active tropical wave with potential for development over the next few days.
"Gusty winds in excess of 70km/hr can be expected along with rainfall accumulations of 75–125 mm. Street or flash flooding are likely in areas of heavy downpours.
"Impacts can include larger than normal waves in both open waters and in the Gulf of Paria. Tree branches and loose objects can be displaced during strong winds. Traffic disruptions are likely in flooded areas. Expect periods of lull between bursts of rainfall and thunderstorm activity."
On Tuesday morning both the Met Office and the Miami-based National Hurricane Center had posted updates.
The Met Office, in a post on its website titled, Active Tropical Wave east of the Southern Windward Islands, said it was monitoring the progress of the wave. It said the system had a medium potential (50 per cent chance) for cyclone development in the next five days, that is by Sunday.
Asked if a cyclone was a hurricane, Dickson later told Newsday, "A cyclone is a broad term for depressions, storms and hurricanes."
The Met Office post said that at 8 am, the leading edge of the tropical wave was about 450 km east of the southern Windward Islands.
"The wave is accompanied by heavy showers and thunderstorms moving westward at 28 km/h. There is the possibility of gradual development over the next few days.
"On this present course, this system is expected to move across the Windward Islands during Wednesday/Thursday. Regardless of cyclone development, this system is expected to bring unstable conditions, resulting in moderate to heavy rainfall accompanied by thunderstorm activity, affecting TT and the Windward Islands."
The Met Office urged the public to stay informed on its website www.metoffice.gov.tt, via its app or by its updates on Twitter, Facebook and Instagram.
Asked what was meant by a cyclone organising or developing, Dickson said it meant all of the energy consolidating into one area, to develop further into a system.
"For tropical cyclones to develop we need those areas of convection, those areas of thunderstorms, to be grouped closely together.
Alternatively, if the thunderstorms stay scattered or patchy, no system will develop.
Dickson said, "This morning it was looking a bit more organised – the thunderstorms were a bit more clustered together – but over the course of the day we've seen that organisation has broken down somewhat. But it is expected to reorganise again sometime tomorrow."
The US National Hurricane Center said on Tuesday morning satellite data showed the tropical wave had just become organised, several hundred miles east of the Windwards , in a statement headlined: 70 per cent chance of cyclone formation in five days.
"Additional development is expected and a tropical depression is likely to form within the next few days as the system moves westward to west-northwestward at 15-20 miles per hour across the eastern and central Caribbean Sea.
"Interests in the Windward Islands should closely monitor the progress of this system as heavy rainfall and gusty winds could affect these islands beginning on Wednesday."
Dickson said, "We've already been experiencing some showers and storms and that will continue into tonight. As we go into tomorrow (Wednesday) between 5-8 am we expect the intensity to go up a bit in terms of the heavier showers and thunderstorms, and then it will peak some time during Wednesday evening to Thursday morning.
"Whether it will develop or not is still a bit uncertain, but regardless of development we're still looking at those periods of heavy showers and thunderstorms."
In terms of predictions by satellite imagery, Dickson said these can give estimates but were limited by the large distances involved.