Tropical Wave 07 Forecast To Bring Scattered Showers, Thunderstorms From Late Sunday

What you need to know:
— A fast-moving tropical wave is approaching Trinidad and Tobago, forecast to move across the islands Sunday night into Monday.
— Scattered showers and isolated thunderstorms are forecast to begin after nightfall on Sunday and continue through midday on Monday with mostly cloudy skies. A dry and breezy evening is forecast on Monday, with Saharan Dust returning across the region.
— There are no alerts, watches, or warnings in effect for T&T from the Trinidad and Tobago Meteorological Service at this time.

The Forecast

The Remainder of Saturday: Hazy with a light breeze. Very brisk, isolated showers possible lasting no longer and 1-2 minutes across both islands.

Sunday: Initially hot and hazy weather forecast across both islands. After midday, conditions will gradually become more humid, with isolated showers developing. By the evening and after nightfall through midnight, cloudiness is forecast to increase across T&T, as the axis of Tropical Wave 07 traverses the region, with isolated to scattered showers and isolated thunderstorms. Heavier rainfall is forecast to remain offshore eastern Trinidad and Tobago.

Monday: Showers and thunderstorms continue from midnight, gradually diminishing towards daybreak, with partly to mostly cloudy skies after sunrise. A few lingering showers are possible through midday, with breezy and hazy conditions returning for the second half of Monday. A mostly fair night is expected.

Marine: Seas are forecast to be slight over the next 36 hours, returning to moderate by the second half of Monday. Waves between 1.0 to 1.5 meters in Trinidad and Tobago’s open waters through Monday morning, becoming up to 2.0 meters by Monday night. Across sheltered coastlines, near calm seas are expected through Monday morning, with waves below 1.0 meters are likely by the evening. In heavy showers or thunderstorms, sheltered seas may become choppy.

Forecast Discussion

As of 5:00 PM, Tropical Wave 07 has been analyzed at 53W, south of 15N, moving westward at 15 to 20 knots (27 to 37 KM/H). This wave is still east of Trinidad and Tobago, but its large plume of moisture and instability will begin to move across the Lesser Antilles from Sunday afternoon.

Though the atmosphere remains fair dry at this time, this tropical wave is forecast to increase moisture at all levels of the atmosphere. Additionally, between 6:00 PM Sunday and 6:00 AM Monday, there will be a marginally supportive atmosphere with somewhat favorable low-level convergence and upper-level divergence for heavy shower and thunderstorm development, though wind shear will remain moderate. With wind shear remaining from the southwest to west, the worst of the weather is forecast to remain offshore northern and eastern Trinidad and Tobago.

By Monday afternoon, the low to mid-levels of the atmosphere are forecast to dry due to a surge of Saharan Dust, limiting further significant rainfall until later next week, when Tropical Wave 08 moves across the region.

Total Precipitable Water Imagery showing the Tropical Waves (analyzed by the National Hurricane Center, Weather Prediction Center, and TTWC) that exist east of Trinidad and Tobago. (CIMSS, Space Science & Engineering Center, University of Wisconsin - Madison)
Total Precipitable Water Imagery showing the Tropical Waves (analyzed by the National Hurricane Center, Weather Prediction Center, and TTWC) that exist east of Trinidad and Tobago. (CIMSS, Space Science & Engineering Center, University of Wisconsin – Madison)

Temperatures

Across both islands, overnight lows are forecast to be mild, with daytime highs hot.

Over the next 48 hours, the minimum low for Trinidad and Tobago is forecast to be between 24.0°C and 27.0°C. The maximum high for Trinidad and Tobago is forecast to be between 30.0°C and 33.0°C.

Forecast Impacts

Forecast impacts due to Tropical Wave 07
Forecast impacts due to Tropical Wave 07

Mainly Sunday night into early Monday morning, the main hazards include heavy rainfall triggering localized street flooding and flash flooding. Lightning and gusty winds up to and in excess of 55 KM/H may accompany thunderstorms or heavy showers and cause power dips/outages, downed trees, and localized wind damage.

On Monday, the main hazards are gusty winds accompanying brisk showers and reduced air quality due to an increase in Saharan Dust.

Winds

Sustained surface winds up to 30 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.

Rainfall

Over the next 72 hours, overall higher rainfall is forecast to favor eastern Trinidad and Tobago, with accumulations between 20 to 30 millimeters as Tropical Wave 07 moves across the region. However, localized totals up to and in excess of 30 millimeters are possible in prolonged heavy showers or isolated thunderstorm activity. Note that highly isolated areas across western and northern areas of Trinidad may exceed daily forecast totals.

  • The remainder of Saturday: Little to no rainfall is forecast, with any accumulations remaining less than 5 millimeters.
  • Sunday: Though no rainfall is forecast through much of the day, from the afternoon through the night, less than 5 millimeters are forecast across the western halves of both islands, but eastern halves between 5-15 millimeters of rainfall are possible, in addition to southern Trinidad. Higher totals may accumulate in localized areas.
  • Monday: Most of the rainfall is forecast to subside during the morning. Still, less than 5 millimeters of rainfall is forecast across the country, with the eastern half of Trinidad recording up to 15 millimeters of rainfall. Higher totals may accumulate in localized areas.

As mentioned earlier, mainly Sunday night into early Monday morning, heavy rainfall may trigger localized street flooding and flash flooding.

Other Adverse Weather Impacts

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.

On Sunday night into Monday morning, scattered rainfall is forecast.

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

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