Tropical Update Overview:
— There are no systems in the Atlantic, as of 8:00 PM Monday, being officially monitored for tropical cyclone development.
— Tropical Wave 2 – A axis of a weak tropical wave moved across Trinidad and Tobago, bringing isolated thunderstorms, showers, and gusty winds on Monday. The wave is now in the Caribbean Sea and across Venezuela.
— Tropical Wave 3 – This weak, low-latitude, tropical wave in the Atlantic is forecast to move across the Windward Islands on Thursday into Friday, bringing potentially heavy rainfall on Friday across T&T.
— Tropical Wave 4 – A tropical wave has emerged in the Atlantic Ocean. This tropical wave is forecast to move across the region next seven to eight days.
— Impacts to T&T – There are no direct tropical threats facing T&T over the next 5 days. Tropical-wave-enhanced rainfall is forecast from late Thursday through the weekend.
Before we dive into the forecast and tropical update, a few notes:
- Tropical waves are a normal part of the rainy season.
- Not every tropical wave will form into a tropical cyclone.
- Weaker tropical waves produce more rainfall across Eastern parts of the islands with mostly cloudy conditions and a few showers across western parts of the islands.
- Rainfall will be more isolated and intermittent with weaker tropical waves that do not have ITCZ or upper-level support.
- Saharan Dust may weaken tropical waves.
Tropical Wave 2
As of the 8:00 PM Tropical Update, the 2nd tropical wave for the 2021 Atlantic Hurricane Season is located from 14N, along 63W based on our analysis. The wave axis is moving westward around 10 to 15 knots (18 to 27 KM/H).
This wave moved across T&T on Monday morning, bringing showers and isolated thunderstorms mainly across the southern half of Trinidad as forecast. Lingering moisture may bring few early morning showers across T&T through the first half of Tuesday as the axis moves westward.
Tropical Wave 3
As of the 8:00 PM Tropical Update, the 3rd tropical wave for the 2021 Atlantic Hurricane Season is located from 13N southward, along 45W, based on our analysis. The wave axis is moving westward around 10 to 15 knots (18 to 27 KM/H). This wave is forecast to move across the region on Friday. However, as this wave moves across T&T, moisture from equatorial regions will accompany the wave axis, moving across the Windward Islands.
With high levels of atmospheric moisture, favorable low-level convergence, and upper-level conditions, scattered showers, isolated thunderstorms, and cloudy skies are forecast mainly from Friday through Sunday. However, cloudiness and showers may begin by late Thursday. The heaviest rainfall is forecast to occur on Friday into Saturday across T&T. Wind shear is also forecast to be light to moderate from the west to southwest, allowing for heavy shower or thunderstorm development but still keeping heavier overall rainfall offshore eastern Trinidad.
Tropical Wave 4
As of the 8:00 PM Tropical Update, the 4th tropical wave for the 2021 Atlantic Hurricane Season is located from 17N southward, along 15W, based on our analysis. The wave axis is moving westward around 10 to 15 knots (18 to 27 KM/H).
This tropical wave is several days away, forecast to move across the region early to the middle of next week. It is too early to tell impacts, if any, to T&T.
At this time, there are no alerts, watches, or warnings issued for T&T from the Trinidad and Tobago Meteorological Service.
Tuesday: After a few morning showers, a mostly hazy, breezy, and partly cloudy day is forecast across Trinidad and Tobago.
Wednesday: A mostly hazy, breezy, and partly cloudy day is forecast. Temperatures will be hot across Trinidad and Tobago.
Thursday: Initially, a mostly hazy, breezy, and partly cloudy day is forecast. By the late morning through the afternoon, an increase in cloud cover and isolated showers are likely through the night due to an approaching tropical wave. Though heavier rainfall will stay offshore, showers and the odd thunderstorm will favor Trinidad’s eastern and southern halves from the afternoon through midnight.
Friday and Saturday: Isolated to scattered showers with mostly cloudy to cloudy skies are forecast across Trinidad and Tobago. Isolated thunderstorm activity is also expected throughout the day, with heavier rainfall favoring eastern and southern areas of both islands, though overall higher totals are forecast to remain offshore. Lingering showers and isolated thunderstorms are forecast through the overnight hours. On Saturday, thunderstorm activity is forecast to mainly stay north of the country.
Sunday: Isolated showers with cloudy periods are forecast across T&T, gradually settling into the evening. Heavier rainfall to favor southern and eastern areas, with isolated thunderstorms possible during the late morning through the afternoon.
Through the forecast period, Saharan Dust concentrations will be variable, with seas remaining moderate in open waters and less than 1.0 meters to near calm in sheltered areas. In heavy showers or thunderstorms, sheltered seas may become choppy.
Across both islands, overnight lows are forecast to be mild, with daytime highs warm.
The minimum low for Trinidad is forecast to be 23.0°C to 25.0°C. In Tobago, a minimum low between 24.0°C to 26.0°C is forecast. The maximum high for Trinidad and Tobago is forecast to be between 30.0°C and 33.0°C, higher across Trinidad. Temperatures may record higher in urban and built-up areas, particularly between 9:00 AM and 3:00 PM. The maximum heat index in Trinidad is forecast to be between 35.0°C and 40.0°C while across Tobago between 33.0°C and 36.0°C. The highest temperatures for the week may occur on Wednesday.
On days with increased cloud cover, such as Friday through the weekend, maximum high temperatures may be lower.
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, absorbing solar radiation more than surrounding areas.
Through the next two days, the main hazards are reduced air quality due to Saharan Dust and gusty winds accompanying brisk showers. However, by later this week, hazards include heavy rainfall and gusty winds, particularly in moderate to heavy showers or thunderstorms, bringing the risk of street flooding or flash flooding.
Heavier rainfall is forecast to favor Western Trinidad during the afternoons while across Eastern and Southern Trinidad during other times of day, reducing visibility and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.
Sustained surface winds up to 35 KM/H. In shower activity, gusts up to and in excess of 55 KM/H are possible. With wind gusts in excess of 55 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.
No significant rainfall is forecast for T&T through the next 48 hours. T&T may experience heavier rainfall by the end of the week due to the passage of Tropical Wave 03.
- Tuesday: Little to no rainfall across the country. Generally, less than 5 millimeters are possible across the southern half of Trinidad
- Wednesday: Little to no rainfall across the country. Isolated totals, favoring southern and western Trinidad less than 5 millimeters.
- Thursday: Less than 5 millimeters, with totals up to 15 millimeters favoring eastern halves of Trinidad and Tobago. Heavier rainfall to remain offshore.
- Friday: Between 10-30 millimeters across the country, with higher rainfall totals favoring southern and eastern areas up to 50 millimeters. Offshore areas may have higher accumulations.
- Saturday: Between 10-20 millimeters across the country, with higher rainfall totals favoring eastern and northern areas up to 40 millimeters.
- Sunday: Less than 10 millimeters across the country, with higher rainfall totals favoring eastern and southern areas up to 20 millimeters.
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.
Lightning: 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.
Brisk, isolated rainfall is forecast Tuesday through Thursday, with scattered to widespread rainfall possible from Friday into Saturday.