Gusty Winds, Heavy Showers and Thunderstorms Forecast As Tropical Wave 15 Moves Across the Lesser Antilles on Thursday into Friday

Tropical Weather Update:
Tropical Wave 15: A vigorous tropical wave is located in the Central Atlantic, a several hundred kilometers East of the Lesser Antilles. As previously forecast, this wave is forecast to bring a surge of moisture across much of the Lesser Antilles late Wednesday through late Friday, increasing cloudiness, showers, and thunderstorms across much of the Lesser Antilles. Severe weather is likely, as favorable conditions are in place for thunderstorm development and gusty winds across the Lesser Antilles, including Trinidad and Tobago. Specifically, for T&T, we expect much of the inclement weather to occur on Friday, while across the remainder of the Lesser Antilles, severe weather is forecast mainly on Thursday.
Tropical Wave 16: This tropical wave is located in the far Eastern Atlantic, forecast to move across Trinidad, Tobago and the remainder of the Southern Windwards on Monday into Tuesday next week. Isolated to scattered showers and isolated thunderstorms are forecast, as this wave is forecast to drag the ITCZ northward across Trinidad and Tobago through Tuesday.
Next Tropical Wave: Though this wave has not been analyzed by the National Hurricane Center as of the 12Z Wednesday 3rd July 2019 Surface Analysis, this wave is forecast to move off the African coast on Saturday into Sunday, moving across Trinidad, Tobago and the Lesser Antilles by late next week – likely between Thursday and Friday. Updates to follow in a subsequent tropical update.
No Tropical Development forecast elsewhere across the Atlantic basin over the next 5 days as of the latest tropical update.

Tropical Wave 15

Tropical Wave 15, nearing Trinidad, Tobago and the Lesser Antilles. Isolated to scattered showers and locally heavy showers/thunderstorms forecast to begin overnight, lingering through Friday. Gusty winds, street flooding, flash flooding, landslides/mudslides, and downed trees all possible through Friday across much of the Lesser Antilles. Credit: Weathernerds.org

The axis of this wave extends its axis along 51W from 15N southward, moving west at 20 knots. This feature continues to be well defined on satellite and total precipitable water imagery also depicts a deep moisture area in addition to the inverted-v shape behind it. Scattered showers and thunderstorms are seen with this wave, from 07N-13N between 49W-53W.

This tropical wave has two vorticity (areas of spin or circulation) centers associated with its axis, one at the mid- to upper-levels at the north of the axis and another at the low-levels along the south of the axis. In addition, a trade wind surge accompanies this wave axis, with winds up to 60 KM/H. The interaction of the trade wind surge, Tropical Wave 15, the ITCZ and these vorticity centers will bring a deep plume of tropical moisture across the Lesser Antilles by this evening (Wednesday), through Friday and support isolated to scattered showers and thunderstorms.

On Wednesday night through Thursday morning, Trinidad and Tobago will see an increase in cloudiness, showers and possible thunderstorms. However, through Thursday, much of the heaviest activity is forecast to occur north of Trinidad and Tobago but scattered showers and isolated thunderstorms remain in the forecast for T&T. A number of islands may issue weather advisories later this evening (example: St. Vincent & The Grenadines) for moderate to rough seas, flooding (street, flash, potential riverine flooding), gusty winds and landslides.

On Friday, based on the latest model guidance, much of the forecast thunderstorm (i.e. heavy rainfall, gusty winds) are forecast to occur. See below for a detailed timeline of events, based on the latest model guidance.

Regardless, expect an adverse weather advisory (either an alert/watch/warning) to be issued for Trinidad and Tobago from the Trinidad and Tobago Meteorological Service, at models continue to trend towards inclement weather over Thursday through Friday, as we have forecast this past Monday, as well as this past Sunday.

What To Expect Over the Next Two Days (Through Early Saturday)

 Tropical Wave 15, nearing Trinidad, Tobago and the Lesser Antilles. Isolated to scattered showers and locally heavy showers/thunderstorms forecast to begin overnight, lingering through Friday. Gusty winds, street flooding, flash flooding, landslides/mudslides, and downed trees all possible through Friday across much of the Lesser Antilles. Credit: Weathernerds.org
Tropical Wave 15, nearing Trinidad, Tobago and the Lesser Antilles. Isolated to scattered showers and locally heavy showers/thunderstorms forecast to begin overnight, lingering through Friday. Gusty winds, street flooding, flash flooding, landslides/mudslides, and downed trees all possible through Friday across much of the Lesser Antilles. Credit: Weathernerds.org

Note: Street/Flash flooding, frequent lightning, gusty winds, landslides/mudslides are all possible beginning overnight tonight (Wednesday) through late Friday (8:00 PM). In addition, locally severe thunderstorms may produce isolated areas, up to 100 millimeters of rainfall, across the Windward Islands.

Wednesday Evening & Night (4:00 PM Wednesday through 12:00 AM Thursday): Increasing cloudiness and humidity is forecast through sunset, with showers likely beginning after 9:00 PM across both Trinidad and Tobago. Intermittent scattered showers with cloudy intervals are likely into Thursday, with possible thunderstorms across Trinidad. The highest chance for thunderstorm activity is forecast across Eastern Trinidad.

Thursday (12:00 AM Thursday through 12:00 AM Friday): Intermittent and scattered, to widespread showers and thunderstorms are likely through the first half of Thursday, with activity shifting north of Trinidad and Tobago. Before sunrise, heavy showers and thunderstorms possible, mainly across Northern Trinidad and Tobago, with light to moderate showers possible across the remainder of Trinidad.

Showers and thunderstorms are forecast to become more sparse throughout the day, with severe thunderstorms south of Trinidad, along Coastal Venezuela. Upper-level clouds may produce a mainly cloudy day across Trinidad and Tobago, with a few showery spells, lingering into nightfall.

Friday (12:00 AM Friday through 12:00 AM Saturday): Isolated showers are forecast to increase in coverage through the early morning. Scattered showers and thunderstorms are forecast to become more widespread by 5-7 AM Friday morning, with the heaviest activity occurring across Southeastern Trinidad, moving west-northwestward as the axis of Tropical Wave 15 moves into the Caribbean Sea. Showers are forecast to decrease in intensity and coverage by the late afternoon, while breezy conditions persist. A few lingering showers are possible by nightfall, with a partly cloudy and breezy night.

Saturday (12:00 AM Saturday through 8:00 AM Saturday): Mostly settled, with the medium to a low chance of an isolated shower, favoring Eastern Trinidad and Tobago leading to a mostly sunny day. Note, an increase in Saharan Dust is forecast as the day progresses, with breezy conditions persisting.

Possible Impacts to Trinidad and Tobago

Locally Heavy Rainfall & Flooding: Based on the 12Z Wednesday model runs, from Wednesday (2:00 PM) through Saturday (2:00 AM), generally, over the 72 hour period, models are in agreement of less than 30 millimeters across Western parts of Trinidad and Tobago, between 30-60 millimeters across Southern, Central and Eastern Trinidad, as well as Eastern Tobago. Isolated rainfall totals up to 100 millimeters possible across Eastern Trinidad. Note that this increase in rainfall is due to the possibility of stronger thunderstorms moving across the islands, producing locally heavy rainfall in short periods.

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, based on the above-mentioned forecast rainfall totals.

Frequent Lightning: In addition, with thunderstorms, frequent lightning is likely. Thunderstorms are forecast to occur mainly on Thursday and Friday, across the Southern Windwards, including Trinidad and Tobago, as well as parts of the French Antilles.

Gusty Winds: Gusty winds, generally up to 60 KM/H are likely. Gusty winds are most likely between 10:00 AM to 5:00 PM, and prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 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.

High Wind Event Precautions
High Wind Event Precautions

Landslides: In landslide-prone areas, particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.

Tropical Wave 16

Tropical Wave 16, embedded within the ITCZ, producing scattered showers near the axis of the wave. This wave is forecast to move across the Lesser Antilles on Monday into Tuesday, bringing another round of possible inclement weather to the islands. Credit: Weathernerds.org

The axis of this wave extends its axis along 29W, south of 14N and is moving westward at 15-20 knots. Scattered showers and thunderstorms are currently associated with this feature, seen from 06N-08N between 28W-30W.

This wave is not forecast to be a huge rainmaker across Trinidad and Tobago, as much of the showers and possible thunderstorms associated with this wave is forecast to occur North of Trinidad, in line with a low-level vorticity maximum. However, increased cloudiness, a few isolated to scattered showers and the isolated thunderstorm are in the forecast, mainly Monday night into Tuesday.

Generally, less than 10 millimeters of rainfall is forecast across Trinidad and Tobago, with isolated totals of 10-30 millimeters are forecast between Monday and Tuesday, generally across eastern parts of the islands.

Note that these totals may change in subsequent tropical updates, nearer to the passage of this tropical wave.

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the month of July. This month, the attention goes to tropical waves moving across the Atlantic, particularly as they near the Lesser Antilles, as well as low-pressure systems in the Gulf of Mexico and troughs Southeast of the United States.

In July, we turn our eyes to East of the Lesser Antilles, the Southeastern areas of the United States and the Gulf of Mexico for the formation of tropical cyclones in the Atlantic Basin, historically. However, tropical cyclones can form in the Atlantic Basin, without regard for the location once conditions support development. Stay updated with the latest tropical update!

There are NO tropical cyclone threats to the Eastern Caribbean, including Trinidad and Tobago at this time in the latest Tropical Update.

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