Tropical Storm Bret is moving quickly towards the Lesser Antilles on Tuesday afternoon and is forecast to move across the central Lesser Antilles islands by Thursday evening. While the core of the system is forecast to remain near St. Lucia and Martinique, showers and thunderstorms are forecast across much of the island chain, with the heaviest rainfall remaining between St. Vincent and the Grenadines to Dominica.
While Tropical Storm Bret poses no direct threat to Trinidad and Tobago at this time, periods of showers and thunderstorms associated with outer bands and influenced convergence from Bret are forecast from Wednesday evening through Friday night across and near the country.
What you need to know
— What has changed: Tropical Storm Bret is now forecast to be a weaker system, a moderate tropical storm, as it moves through the central Lesser Antilles, with the track for the center of circulation adjusted marginally south. While the stronger winds are still forecast to remain north of the center of circulation, heavy rains trailing the center may affect much of the Windwards and French Antilles.
— Where is it forecast to move: Forecast models have honed in on the center of circulation moving across the central Lesser Antilles, well north of Trinidad and Tobago.
— The Intensity & Impacts: The current forecast track places islands northward of St. Vincent and Barbados and southward of Dominica at the highest risk for damaging winds, flooding rainfall, storm surge, and hazardous seas. The National Hurricane Center’s forecast calls for a tropical storm with sustained winds up to 100 KM/H and gusts to 120 KM/H moving across the central Lesser Antilles. For the southern Windwards, southward of St. Vincent and the Grenadines, as well as Barbados to Trinidad and Tobago, feeder bands could extend southward, bringing showers/thunderstorms and gusty winds. In addition, light to near-calm winds will lead to increased daytime temperatures, localized, slow-moving afternoon showers and thunderstorms, and agitated seas mainly on Thursday, with increased winds from the southeast on Friday.
— Latest from officials: A tropical storm watch is now in effect for Barbados. Additional watches will be required for other islands later tonight. T&T is not under any tropical storm watch or warning.
The latest
At 5:00 PM Tuesday, June 20th, 2023, Tropical Storm Bret’s approximate center of circulation was located at 12.2°N and 48.6°W, placing the center approximately 1,330 kilometers east of Tobago and 1,230 kilometers east of Barbados.
According to the National Hurricane Center’s 5:00 PM Advisory, Tropical Storm Bret is moving west at a brisk pace of 30 KM/H, and this is forecast to continue for the next several days, approaching the Lesser Antilles by Thursday into Friday.
Maximum sustained winds have increased to 75 KM/H with gusts to 90 KM/H, with strengthening forecast over the next day or so. The NHC says this system is forecast to remain a tropical storm as it moves across the Lesser Antilles, with weakening forecast thereafter in the Caribbean Sea. The current minimum central pressure is 1006 millibars, with tropical-storm-force winds extending outwards up to 75 kilometers from the center.
Tropical Storm Bret continues to produce bursts of convection on the east side of the circulation. There is some westerly shear affecting Bret over the last 24 hours, which has limited strengthening, and elevated westerly shear is forecast to continue, particularly at the mid-levels of the atmosphere. However, with sea-surface temperatures between 27°C and 29°C, strengthening remains forecast.
Current Watches & Warnings
Tropical storm watches are now in effect for the following countries:
- Barbados
- Dominica
A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.
Interests elsewhere in the Lesser Antilles should monitor the progress of Bret. Tropical storm watches will likely be required for other islands later tonight.
There are no alerts, watches, or warnings in effect for Trinidad and Tobago at this time from the Trinidad and Tobago Meteorological Service.
Track and Intensity
Tropical Storm Bret is following a low to mid-level ridge, pushing the storm quickly west to west-northwestward. However, this fast forward movement, particularly at the lowest levels, has prevented the system from strengthening further. Given that Bret remains weaker, this near-westward motion is forecast to continue into the Lesser Antilles, with a weaker system moving slightly faster into the central Lesser Antilles than explicitly forecast. Given that the NHC’s average errors for the two and three-day periods are between 60 to 75 nautical miles, it is still too soon to know exactly where the center will track across the Lesser Antilles chain.
With westerly shear affecting Bret through the next several days, no significant strengthening is forecast, and while the system is still expected to remain a tropical storm as it moves through the Lesser Antilles, it is expected to dissipate in the eastern Caribbean Sea. The National Hurricane Center is forecasting Tropical Storm Bret to move across the central Lesser Antilles with sustained winds up to 100 KM/H and gusts to 120 KM/H, in line with most reliable intensity models.
What could be the impacts?
For Barbados and the central Lesser Antilles, tropical-storm conditions are possible on Thursday with sustained winds up to 100 KM/H, which can produce wind damage across the islands. Seas are forecast to become hazardous, with forecast rainfall totals likely to produce street/flash flooding and landslides.
For St. Vincent, southward to Tobago (and to a lesser extent Trinidad), and north of Guadeloupe, feeder bands could produce periods of heavy rainfall and gusty winds which would be capable of producing localized wind damage, street/flash flooding, and locally rough/choppy seas.
For the remainder of the Leewards and westernmost Greater Antilles, little to no major impacts are forecast.
Wind
As mentioned above, the National Hurricane Center is forecasting, as of 5:00 PM Tuesday, June 20th, 2023, a tropical storm with sustained winds up to 100 KM/H and gusts to 120 KM/H moving across the French Antilles, mainly between St. Vincent and Dominica.
Certainty has increased in both track and intensity, with nearly all intensity models, in line with the National Hurricane Center’s forecast, showing a tropical storm (at the 48-hour mark in the above graphic) at the time of Bret’s passage across the Lesser Antilles.
Over the last 24 hours, the track has shifted south as a result of Bret remaining weaker than initially forecast with the latest track marginally northward.
With weaker tropical cyclones, the stronger winds generally remain on the northern half of the system’s circulation, meaning St. Lucia, Martinique, Dominica, and even Guadeloupe, could see winds of tropical storm strength.
With feeder bands forecast to traverse much of the eastern Caribbean over the next 48-72 hours, the National Hurricane Center has the entire eastern Caribbean area under a low to medium probability of experiencing tropical storm-force winds, but higher probabilities exist for the northern half of the island chain.
While the southern Windwards aren’t in the direct line of fire from Tropical Storm Bret at this time, outer bands from the tropical cyclone could still have strong showers and thunderstorms that produce tropical-storm-force wind gusts or sustained winds for brief moments – hence the risk is not zero.
Global models, which keep Bret weaker, show higher winds remaining north of the southern Windward Islands, including Trinidad and Tobago. As mentioned earlier, when strong low-pressure systems (strong tropical waves, tropical storms, or even hurricanes) move sufficiently north of T&T, the winds across Trinidad and Tobago become light to near-calm as the pressure gradient across the area slackens. By Friday, across Trinidad and Tobago, winds are forecast to increase from the southeast, with faster-moving showers and thunderstorms forecast.
Rainfall
Generally, rainfall totals associated with Bret are forecast to range between 50 and 150 millimeters (2-6 inches), with higher totals up to 250 millimeters (10 inches) along Windward facing coastlines near the center of circulation in the central Lesser Antilles. Isolated higher amounts are possible, but the fast-moving nature of Bret is forecast to limit persisting heavy rainfall and higher accumulations.
As mentioned above, feeder bands, convergence associated with Bret, and local topography could produce locally heavy rainfall totals that may trigger localized flooding and mudslides/landslides. Ultimately, all islands across the Lesser Antilles should remain on guard for some form of flooding rainfall associated with this tropical cyclone later this week, whether there is a direct impact or not.
Seas and Storm Surge
Similar to the rainfall totals, how agitated seas become and the level of storm surge is dependent on the strength of the tropical cyclone.
Forecast models are showing waves in open waters are forecast to exceed 2.5 meters and up to 3.5 meters near east-facing coastlines. For areas near the center, waves can reach as high as 6.5 meters (21 feet) in open waters. These higher seas are forecast to remain well north of Trinidad and Tobago, with hazardous seas likely from St. Vincent and the Grenadines, as well as Barbados northward.
For Trinidad and Tobago
In nearly all forecast model guidance as of 5:00 PM Tuesday, June 20th, 2023, Bret’s center of circulation moves well north of Trinidad and Tobago.
As the system nears on Wednesday night into Thursday, convergence ahead of the tropical cyclone, with winds coming from the northeast to north, moves some of the outer bands across the southern Windwards and Trinidad and Tobago. Then, on Thursday, as the center tracks north of Barbados, showers and thunderstorms move across Trinidad, Tobago, and the southern Windwards from the south to the north, feeding into the circulation (feeder bands and localized climatic effects). By Friday into Saturday, southerly to southeasterly wind flow feeds into the tropical cyclone with showers and thunderstorms trailing, moving across Trinidad, Tobago, and the Windwards again.
On Thursday, due to slack to near-calm winds, localized climatic effects like daytime heating, sea breeze convergence, and orographic effects take over, producing slow-moving showers and thunderstorms that are enhanced by topography. These effects can trigger locally heavy rainfall, producing street/flash flooding, gusty winds, and other hazardous weather impacts in localized areas while most of the region experience sweltering temperatures.
Pay close attention to official forecasts in the coming days from your respective authorities. For Trinidad and Tobago, official forecasts and early warnings come from the Trinidad and Tobago Meteorological Service.
