Locally Heavy Rainfall on Wednesday into Thursday

Though the peak of the wet season is behind us as the Intertropical Convergence Zone drifts southward and tropical waves have stopped moving off the coast of Africa, other weather features continue to trigger rainfall across Trinidad and Tobago. Hence, the wet season carries on, for now.

In fact, a locally heavy rainfall event is forecast on Wednesday into Thursday as favorable low-level and upper-level conditions will support isolated to scattered showers and possible isolated thunderstorms across both islands, with heavier activity favoring Trinidad.

Note that heavy showers and thunderstorms will be short-lived due to howling wind shear across the region, up to 100 knots (185 KM/H) at times in some areas. This will impact the development of deep convection and persisting thunderstorms by tearing away the tops of the convection.

The Extended Weather Forecast

Tuesday: Brisk, isolated showers are forecast throughout the day affecting both islands, interrupting partly cloudy and breezy conditions. Heavier showers and isolated thunderstorms are forecast to favor Eastern and Southern Trinidad, as well as eastern coastal waters. After nightfall, increasing showers, becoming scattered, and cloudiness are forecast. Locally heavy rainfall and gusty winds, up to 65 KM/H possible. Seas are forecast to be rough to occasionally very rough, with waves between 3.0 meters to 3.5 meters, occasionally up to 4.0 meters in open waters, particularly in Eastern Coastal Waters. A Hazardous Seas Alert #2 remains in effect through 2 PM Wednesday.

Wednesday: Isolated to scattered showers are forecast across both islands, with heavier showers and isolated thunderstorms favoring Eastern and Southern areas of both islands. These showers will interrupt partly cloudy to cloudy skies. Showers are forecast to become more scattered by the evening through the night with mostly cloudy skies. Locally heavy rainfall and gusty winds up to 65 KM/H possible. Seas are forecast to remain rough into Thursday, although that Hazardous Seas Alert #2 expires at 2 PM.

Thursday: Isolated to scattered showers are forecast across both islands, with heavier showers and isolated thunderstorms favoring Eastern and Southern areas of both islands, particularly during the afternoon. These showers will interrupt partly cloudy to cloudy skies. Showers are forecast to become more scattered by the evening through the night with mostly cloudy skies. Locally heavy rainfall and gusty winds up to 65 KM/H possible. Seas are forecast to start off rough, gradually returning to moderate levels by late Thursday.

Friday: The unsettled pattern remains mostly unchanged, with slow-moving isolated to scattered showers throughout the day bringing the threat of gusty winds. Conditions to become unfavorable for thunderstorms. Showers to interrupt partly cloudy to mostly cloudy skies, with heavier activity favoring the afternoon hours. Isolated showers to continue into nightfall.

Saturday: The unsettled pattern remains mostly unchanged, with slow-moving isolated to scattered showers throughout the day bringing the threat of gusty winds. Conditions to become unfavorable for thunderstorms. Showers to interrupt partly cloudy to mostly cloudy skies, with heavier activity favoring the afternoon hours. Isolated showers to continue into nightfall.

Impacts This Upcoming Week

Hazardous Seas: Although the Hazardous Seas Alert #2 is slated to expire at 2 PM Wednesday 15th January 2020, model guidance continues to show rough seas continuing into Thursday, with seas returning to moderate levels late Thursday through the weekend. Another rough seas event (much more short-lived) is forecast at the beginning of next week.

Sea state forecast for the next 7 days. A Hazardous Seas Alert #2 is in effect. No alerts in effect for inclement weather ahead of the heavy rainfall event forecast.
Sea state forecast for the next 7 days. A Hazardous Seas Alert #2 is in effect. No alerts in effect for inclement weather ahead of the heavy rainfall event forecast.

Winds: Sustained surface winds between 20 KM/H and 40 KM/H with gusts up to 65 KM/H are likely, accompanying all showers or thunderstorms across Trinidad and Tobago.

With wind gusts up to 65 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. Roof damage is also possible.

High Wind Event Precautions
High Wind Event Precautions

Rainfall: Throughout the week, daily rainfall accumulations are forecast to be isolated totals of less than 10 millimeters, with in excess of 15 millimeters in isolated thunderstorms or heavy downpours. Daily rainfall accumulations may range between 15-35 mm on Wednesday and Thursday.

On Wednesday, rainfall totals between 25-75 millimeters are possible, favoring Eastern and Southern Trinidad, as well as Tobago.

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.

This week, isolated to scattered activity is forecast.

Forecast - Isolated, Scattered, Widespread - What do they mean?

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