Following two days of relatively cool temperatures across T&T, the heat is forecast to return on Tuesday as a surface to low-level ridge builds and atmospheric moisture briefly decreases. However, unlike our past week, winds are forecast to increase due to the presence of a low-level jet (a narrow band of fast-moving air at low levels of the atmosphere).
A weak tropical wave (Tropical Wave 52) is moving across the islands today as well through the mid-morning, but much of the activity will remain north of T&T.
By nightfall, moisture ahead of Tropical Wave 53 begins to move across the islands, with the ITCZ north of T&T. Due to a favorable mid to upper-level atmosphere, isolated to scattered showers and thunderstorms are possible across T&T, particularly after midnight. This activity will persist through Friday, with periods of heavy rainfall forecast for T&T.
With a low-level jet present across the region, particularly in areas where strong showers and thunderstorms occur, gusty winds may mix down to the surface, producing downburst-like activity with damaging wind gusts, particularly on Wednesday through Friday.
There are no alerts, watches, or warnings from the Trinidad and Tobago Meteorological Service at this time.
Overview: A surface to low-level high-pressure ridge is forecast to briefly strengthen, reducing atmospheric moisture and increasing wind speeds across the region, particularly due to the presence of a low-level jet. Tropical Wave 52 will move across the islands today but much of the shower and thunderstorm activity will remain north of T&T. Daytime heating and sea breeze convergence are may act as triggers for late morning afternoon shower and thunderstorm development, though precipitation chances remain low for Tuesday.
Forecast: A mostly hot and sunny day is forecast across both islands. By the late morning, partly cloudy skies are forecast to develop Trinidad. By 11 AM, isolated showers are possible, mainly across hilly areas, but by the afternoon, isolated thunderstorms are possible across Western Trinidad. Conditions are forecast to settle by the evening, with shower and thunderstorms possible by nightfall, particularly after midnight.
Marine: Seas are forecast to be slight to moderate. Generally, in open waters, waves between 1.0 meter and 1.5 meters are possible, particularly north and east of T&T. In sheltered areas, generally below 1 meter to near calm conditions.
Hazards: With mostly settled conditions, today’s high temperatures and heat indices will be the main hazard so particularly between 9:00 AM and 3:00 PM, stay cool and hydrated! In the event of a heavy downpour or thunderstorm during the afternoon, the main hazards include localized heavy rainfall, which may reduce visibility and gusty winds in downburst-like fashion, up to and in excess of 50 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible.
Across both islands, hot and somewhat humid conditions are forecast. The maximum high for Trinidad is forecast to be near 34.0°C, up to 37.0°C in urban and built-up areas, particularly between 9:00 AM and 3:00 PM. In Tobago, the maximum high is forecast to be near 33.0°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 near dangerous levels on Tuesday across Trinidad and Tobago. The heat index and 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, the maximum heat index is forecast to be between 35°C and 45°C and even higher in urbanized areas. In Tobago, the maximum heat index is forecast to be between 35°C and 42°C
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.
Heat index is generally classified into four categories: caution, extreme caution, dangerous, and extremely dangerous. On Tuesday, the heat index is forecast to be near dangerous levels! Remain hydrated!
Sustained surface winds will be light but increasing throughout the day. By the afternoon, sustained winds between 25 KM/H and 35 KM/H with gusts up to and in excess of 50 KM/H are possible.
With wind gusts in excess of 50 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, little to no rainfall is anticipated, with maximum accumulation totals near 5 millimeters. In areas where isolated heavy showers or thunderstorms occur, accumulations up to 25 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.
Highly isolated rainfall is forecast on Tuesday. Most will experience very hot and sunny conditions.