A surface to low-level shear line resulting from the influence of Tropical Storm Laura is approaching Trinidad and Tobago. This activity will produce isolated to scattered showers and thunderstorm activity after midnight through Sunday afternoon, with heavier activity favoring Trinidad.
There are no alerts, watches, or warnings in effect from the Trinidad and Tobago Meteorological Service as of 10:00 PM Saturday 22nd August 2020.
Abundant low-level moisture associated the last of Tropical Storm Laura will be moving across T&T, associated with a surface to low-level shearline, increasing surface to low-level instability across the region tonight. Occasionally cloudy skies with light to moderate showers and possible isolated thunderstorms are expected during the passage of this feature. Conditions are expected to gradually improve across by Sunday afternoon. Favorable low-level convergence and low wind shear will allow for isolated strong thunderstorms and heavy showers mainly across Trinidad.
Through the afternoon on Sunday, isolated strong thunderstorms are possible across Trinidad and Tobago. These thunderstorms may produce damaging wind gusts, flooding rainfall, and dangerous lightning.
Through tonight, mainly after 2:00 AM, isolated to scattered showers and thunderstorms are forecast to begin Trinidad, as well as Tobago, with heavy rainfall forecast through daybreak. Conditions will gradually subside through the morning, with lingering light to moderate rain, but isolated thunderstorms and showers may return during the late morning through the afternoon across both islands, generally favoring Southern and Western areas of Trinidad
A mostly settled evening into the night is forecast across both islands with the odd lingering shower. An increase in Saharan Dust is anticipated
Seas forecast to be slight to moderate, with waves up to 1.5 meters in open waters. In sheltered areas, near calm but choppy in areas of heavy showers or thunderstorms.
The main hazards include heavy rainfall, which may reduce 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 also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage. Landslides are possible in heavy rainfall.
Note that with weak winds, from the northeast on Sunday, with sea breeze convergence, heat, and orographic effects may act as triggers for additional shower and thunderstorm development across western and hilly areas of Trinidad, particularly on Sunday afternoon.
Sustained surface winds will be weak, generally below 25 KM/H, increasing to 40 KM/H during the afternoon at its peak. However, Gusts up to and in excess of 55 KM/H are possible in heavy showers or thunderstorms across Trinidad and Tobago.
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.
Overall, less than 10 millimeters are forecast, with areas across southern and western Trinidad recording up to 25 millimeters, particularly in slow-moving downpours or thunderstorms.
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: In addition, with forecast thunderstorms, frequent lightning is likely. 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 Constant 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.
Scattered activity is forecast through the early morning, gradually becoming isolated as the day progresses on Sunday.