Tropical Wave 59, a weak tropical wave, is moving across T&T and the Lesser Antilles on Monday night. A favorably positioned upper-level trough is enhancing activity mainly north and east of T&T. Still, brief shower and thunderstorm activity is forecast over the next 36 hours.
Higher rainfall accumulations are forecast to favor isolated areas of West-Central and Northern Trinidad and Tobago, though rainfall will be brief.
There are no alerts, watches, or warnings from the Trinidad and Tobago Meteorological Service at this time.
Forecast For Monday Into Tuesday
Forecast: Variably cloudy skies are forecast across T&T overnight, with increasing cloudiness after midnight. Isolated showers and thunderstorms are forecast to remain offshore, affecting eastern areas. On Tuesday, an initially settled start to the day will give way to brief showers and isolated thunderstorms across Trinidad from the late morning through the afternoon. By the late afternoon, showers and thunderstorms may favor the northern half of Trinidad, as well as Tobago.
Conditions will gradually settle through the night, with brisk, isolated rainfall possible.
Hazards: The main hazards include brief but heavy to violent rainfall, which may reduce visibility and gusty winds up to and in excess of 45 KM/H. Street or flash flooding will be possible in violent showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.
Marine: Seas are forecast to be moderate, with waves up to 2.5 meters in open waters. Swells are forecast to be from the north to the northeast, with a swell period between 10 to 14 seconds. In sheltered areas, below 1 meter. However, in areas where thunderstorms occur, seas can become choppy and locally rough.
Winds are forecast to be between 10 to 15 knots prevailing from the east to southeast.
Forecast Discussion: Tropical Wave 59 is traversing the Lesser Antilles. An upper-level low centered near 14N, 59W is enhancing activity, mainly northeast of T&T. Moisture trailing the wave will continue to affect T&T, with that upper-level low enhancing showers and thunderstorms. Winds are forecast to reduce slightly across the region on Tuesday through Wednesday.
Across Trinidad, by the late morning through the afternoon, light winds, daytime heating, and sea breeze convergence will act as triggers for shower and thunderstorm development across western parts of Trinidad, with orographic lift triggering/enhancing showers along hilly topography.
Activity will be enhanced by favorable upper-level conditions due to the positioning of an upper-level trough. However, strong southwesterly wind shear will limit persisting deep convection, keeping heavier activity to our east.
Across both islands, even with the forecast showers and thunderstorms, warm and humid conditions are anticipated. Trinidad’s maximum high is forecast to be near 32.0°C, up to 34.0°C in urban and built-up areas. In Tobago, the maximum high is forecast to be near 31.0°C.
Temperatures in cities, such as Port of Spain, tend to be much higher than surrounding locations due to a phenomenon called the Urban Heat Island Effect. There are several causes, but the main instigator for this phenomenon tends to be increased dark surfaces such as roads and pavement in cities, which absorb solar radiation more than surrounding areas.
The Heat Index
The heat index will be high across Trinidad and Tobago. The heat index is a combination of air temperature and relative humidity, determining what the air feels like to a person, i.e., how hot it actually feels.
Across Trinidad and Tobago, the maximum heat index is forecast to be between 33°C and 38°C and even higher in urbanized areas.
The heat index is important because of sweating. Your body sweats to cool the skin and maintain a constant, healthy body temperature. This cooling process means that the sweat has to evaporate off the skin to remove heat. However, if the sweat is unable to evaporate, the body isn’t able to regulate temperature.
Sustained surface winds will be light, peaking during the afternoon. By the afternoon, sustained winds up to 20 KM/H with gusts up to and in excess of 45 KM/H are possible.
With wind gusts in excess of 45 KM/H, whole trees are expected to be in motion, and there may be some inconvenience when walking against the wind gusts. Light outdoor objects may topple or become airborne such as garbage cans, potted plants, loose galvanize or construction material, and other outdoor furniture. Tents may jump. Older/weaker trees may fall, bringing down utility poles and lines.
Across most areas of Trinidad and Tobago, low rainfall accumulations are anticipated, with maximum accumulation totals less than 5 millimeters over the next 36 hours.
In isolated areas across Trinidad, rainfall accumulations between 15-25 millimeters are possible. In areas where torrential rainfall occurs with possible severe thunderstorms, accumulations up to 50 millimeters are possible.
Generally, with heavy showers and thunderstorm activity, street flooding, particularly in flood-prone areas or areas with poor drainage, is possible as well as flash flooding in areas where more prolonged heavy rainfall may occur.
Frequent Lightning: Frequent lightning is possible in thunderstorm activity. Lightning can cause power outages, voltage dips, damage to life and property, particularly during cloud-to-ground lightning strikes.
Why I May Not/Will Not See Rainfall?
A frequent complaint is the forecast is wrong because I didn’t experience any rainfall. Scattered showers mean that you, individually, may experience some showers intermittently throughout the day and there is a higher chance for this activity than isolated activity. Widespread showers mean that nearly all persons and areas may experience rainfall.
Brief, isolated to scattered rainfall is forecast on Monday night and Tuesday, interrupting partly to mostly cloudy periods as Tropical Wave 59 moves westward.