Tropical Wave 09 Forecast To Move Across T&T Over Next 72 Hours

What you need to know:
— A large, well-defined but weak tropical wave is forecast to move across Trinidad and Tobago on Wednesday night into Thursday. However, a band of moisture (not the Intertropical Convergence Zone) is forecast to begin affecting T&T from tonight.
— Scattered showers and isolated thunderstorms are forecast to begin near midnight tonight and continue through Thursday, with periodic mostly cloudy to cloudy skies. High concentrations of Saharan Dust remain across the region, which may limit rainfall.
— There are no alerts, watches, or warnings in effect for T&T from the Trinidad and Tobago Meteorological Service at this time.

The Forecast

Tuesday night: A partly cloudy night is forecast across T&T with isolated to scattered showers developing near and after midnight, favoring southern and eastern areas initially.

Wednesday: Partly to mostly cloudy skies with scattered showers through the morning. By the late morning through the afternoon, scattered showers, with isolated heavy showers and isolated thunderstorms, are forecast to favor Trinidad, gradually settling by the evening. However, a resurgence of showers and isolated thunderstorms are forecast after nightfall, favoring offshore areas mainly.

Thursday: Showers and thunderstorms continue from midnight with few showers and partly to mostly cloudy skies continuing into the morning. By the late morning, isolated thunderstorms are possible across both islands, settling by the evening. Lingering showers are possible overnight

Marine: Seas are forecast to be moderate over the next 72 hours, with waves between 1.5 to2.0 meters in Trinidad and Tobago’s open waters. Across sheltered coastlines, waves below 1.0 meters are expected, with choppy seas in the vicinity and during heavy showers or thunderstorms.

Forecast Discussion

As of 3:00 PM, Tropical Wave 09 has been analyzed at 50W, south of 15N, moving westward at 15 to 20 knots (27 to 37 KM/H). There is no significant convection (showers and thunderstorms) associated with this tropical wave at this time. However, scattered showers are noted between 8N and 11N between 50W and 60W associated with a band of moisture ahead of the tropical wave.

This band of moisture is forecast to move across T&T overnight tonight (Tuesday night) and drift northwestward with additional moisture associated with the tropical wave moving across T&T from Wednesday afternoon and lingering through Thursday afternoon. Elevated moisture at all levels of the atmosphere is forecast to fuel scattered showers and isolated thunderstorms over the next 72 hours.

A mostly supportive atmosphere is forecast on Wednesday and into Thursday with favorable low-level convergence and upper-level divergence, supportive of heavy shower and thunderstorm development. Wind shear will be light to moderate, allowing for heavy to violent rainfall to occur during shower or thunderstorm activity. Still, this rainfall event is not forecast to be widespread due to the presence of Saharan Dust, creating somewhat unfavorable mid-level conditions at times.

Notably, further north of T&T on Thursday, a surge of trade winds is forecast to envelop the Leewards and French Antilles, bringing gusty winds and windy conditions to that region. Similar conditions are not expected for the Southern Windwards.

For those asking “where did Tropical Wave 08 go?” It was dropped from analysis as its wind signature dissipated.

Visible satellite imagery showing scattered showers east of Trinidad and Tobago associated with a band of moisture and the approaching Tropical Wave 09.

Temperatures

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

Over the next 72 hours, the minimum low for Trinidad and Tobago is forecast to be between 24.0°C and 26.0°C. The maximum high for Trinidad and Tobago is forecast to be between 29.0°C and 32.0°C.

Forecast Impacts

Forecast impacts due to Tropical Wave 07

Mainly Wednesday into Thursday, the main hazards include heavy rainfall triggering localized street flooding and flash flooding. Lightning and gusty winds up to and in excess of 60 KM/H may accompany thunderstorms or heavy showers and cause power dips/outages, downed trees, and localized wind damage.

Winds

Sustained surface winds up to 30 KM/H. In shower activity, gusts up to and in excess of 60 KM/H are possible. With wind gusts in excess of 60 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 and southern areas of Trinidad and Tobago, with accumulations between 20 to 30 millimeters as Tropical Wave 09 moves across the region. However, localized totals up to and in excess of 50 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.

  • Wednesday: Between 0-10 millimeters of rainfall across the country with areas across eastern and southern areas of Trinidad and Tobago receiving up to 25 millimeters. In isolated areas across the country, particularly western Trinidad, in heavy to violent showers and thunderstorms, localized totals may exceed 25 millimeters.
  • Thursday: Between 0-10 millimeters of rainfall across the country with areas across eastern and southern areas of Trinidad and Tobago receiving up to 20 millimeters. In isolated areas across the country, particularly western Trinidad, in heavy to violent showers and thunderstorms, localized totals may exceed 25 millimeters.

As mentioned earlier, mainly Tuesday night into Thursday evening, 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 Tuesday night, isolated to scattered rainfall is forecast while on Wednesday through Thursday, isolated to scattered showers and thunderstorms are forecast.

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

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