Atlantic Tropical Update: Tropical Wave to Move Across T&T on Friday, Bringing Showers & Thunderstorms

Tropical Weather Update:
Tropical Wave 12: This wave is located just east of the Lesser Antilles. However, this wave is devoid of convection due to its location within a plume of Saharan Dust and a dry mid-level environment. Very little change in weather is forecast as this wave traverses the region on Thursday.
Tropical Wave 13: This wave is located in the Central Atlantic, embedded within the ITCZ. The axis of this wave is forecast to move across Trinidad and Tobago on Friday, bringing the ITCZ closer to T&T as well. Cloudy skies, scattered to widespread showers and isolated thunderstorms, mainly across Trinidad, are in the forecast. Locally heavy rainfall and gusty winds are possible due to favorable atmospheric conditions forecast. Possible locally severe weather.
Tropical Wave 14: A new tropical wave is moving off the African Coast with scattered moderate and isolated strong showers and thunderstorms occurring near the axis of the wave. This wave is forecast to move across T&T on Monday into Tuesday. Saharan Dust will limit showers and thunderstorms across T&T during this period.
No Tropical Development forecast elsewhere across the Atlantic basin over the next 5 days as of the latest tropical update.

Tropical Wave 12

The axis of this wave is located along 53W from 02N-20N, moving west around 15 knots. Dry Saharan air surrounds the wave, limiting convection at this time. The wave is clearly identifiable from 700 millibar trough diagnostics as well as a surface trough seen in the ASCAT scatterometer observations.

This wave is not forecast to bring any notable change in the dry, dusty weather ahead of Tropical Wave 13. No impacts to Trinidad and Tobago forecast.

Tropical Wave 13

Tropical Wave 13 in the Central Atlantic, with scattered showers and isolated thunderstorms near the wave axis. This wave has a large moisture field, so showers and possible thunderstorms are in the forecast on Friday into early Saturday for T&T Image Credit: Weathernerds.org
Tropical Wave 13 in the Central Atlantic, with scattered showers and isolated thunderstorms near the wave axis. This wave has a large moisture field, so showers and possible thunderstorms are in the forecast on Friday into early Saturday for T&T Image Credit: Weathernerds.org

This tropical wave’s axis extends along 38W, from 06N to 17N, moving west at 15 knots. Scattered moderate showers and isolated thunderstorms are noted from 05N-07N between 36W-40W. The position of the wave is mainly based upon a maximum in Total Precipitable Water east of the wave axis along with 700 millibar trough diagnostics. No significant surface signature is present with this wave.

This wave is forecast to move across T&T on Friday into the early hours of Saturday of next week, bringing increased cloudiness, scattered showers and possible thunderstorms, favoring Trinidad. The ITCZ may also pay another visit to the islands, beginning Thursday night, which may bring a heavy rainfall threat.

In addition, an upper level trough will be favorably positioned on Friday into Saturday. This is forecast to create favorable upper level divergence, aiding in the development and sustaining deep convection such as heavy showers and thunderstorms across the Southern Windwards, including Trinidad and Tobago.

As of this tropical update, this wave is not forecast to produce widespread severe weather. However, isolated to scattered severe weather is possible as isolated to scattered heavy showers and thunderstorms are in the forecast as well as gusty winds. This potential severe weather is likely to begin by 2:00 AM Friday, through 8:00 AM Saturday. An Adverse Weather advisory (alert/watch/warning) may be issued by the Trinidad and Tobago Meteorological Service on Thursday.

Forecast For Trinidad and Tobago

Thursday, through midnight (12:00 AM Thursday to 12:00 AM Friday) – Initially sunny and slightly hazy conditions across Trinidad and Tobago. A few isolated showers are possible during the late morning through the late afternoon, due to an induced trough from the ITCZ, coupled with a surge in moisture ahead of Tropical Wave 13.

Friday, through midnight (12:00 AM Friday to 12:00 AM Saturday) – Mostly cloudy skies with periods of showers, mainly across Trinidad. Thunderstorms are also possible throughout the day likely by the late morning through the afternoon, accompanied by gusty winds. This activity is forecast throughout Friday, leading into nightfall on Saturday.

Saturday, after midnight through 8:00 AM (12:00 AM Saturday to 8:00 AM Saturday) Initially isolated to scattered showers and the isolated thunderstorm overnight through dawn will give way to a partly cloudy morning. Much of the possible inclement weather is forecast to subside by 8:00 AM.

The Remainder of Saturday, until midnight (12:00 AM Saturday to 12:00 AM Sunday) – An increase in low-level winds, as well as Saharan Dust, is forecast as the day progresses, with degrading air quality. The upper-level trough is forecast to generate some mid to upper-level clouds across the region, resulting in a partly to mostly cloudy but hazy day.

Possible Impacts to Trinidad and Tobago

Locally Heavy Rainfall & Flooding: Based on the 12Z Tuesday model runs, from Thursday night (8:00 PM) through Saturday morning (8:00 AM), generally less than 15 millimeters across Tobago, with locally heavier amounts along the Southern coast of the island or where thunderstorms/heavy showers occur.

Across Trinidad, heavy rainfall is likely across Eastern parts of the island, with rainfall totals generally between 20-40 millimeters, and isolated areas receiving up to 60 millimeters, as of the latest model guidance. Across Southern and Central Trinidad, generally, 20-40 millimeters of rainfall is also forecast. Western and Northwestern Trinidad may see the “lowest” totals, as expected with weaker tropical waves in June, with generally less than 20 millimeters of rainfall forecast over the 36 hour period, though isolated heavier totals are possible in the vicinity of thunderstorms or heavy showers.

The heaviest activity is forecast to occur on Friday. 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 after midnight Friday, through the early hours of Saturday, across T&T.

Gusty Winds: Gusty winds, generally between 50-60 KM/H are likely. Gusts up to 75 KM/H are possible across Eastern Tobago and higher elevations across the Northern Range, Trinidad, while peak gusts across the majority of Trinidad and Tobago of up to 70 KM/H may occur. Gusty winds are most likely during the latter half of Friday. These wind gusts will generally occur prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 74 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, loose galvanize or construction material and other outdoor furniture. Tents may jump.

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 14

Tropical Wave 14, moving off the West African Coast on Wednesday evening. Scattered showers and locally heavy showers/thunderstorms are occurring near the axis of this wave. It is forecast to move across T&T on Monday into Tuesday next week. Credit: Weathernerds.org
Tropical Wave 14, moving off the West African Coast on Wednesday evening. Scattered showers and locally heavy showers/thunderstorms are occurring near the axis of this wave. It is forecast to move across T&T on Monday into Tuesday next week. Credit: Weathernerds.org

A new tropical wave has been analyzed in this afternoon’s tropical update. The axis of this wave is located along 10-15W moving westward. Scattered showers with locally heavy showers and thunderstorms are occurring across Western Africa. This wave has a well-defined trough at the 700 millibar level.

Tropical Wave 14 is forecast to move across Trinidad and Tobago by Monday, July 1st, 2019. However, dense Saharan Dust is forecast to be across the region. This dust will keep the mid-level atmosphere fairly dry, hindering convection (showers and thunderstorms).

Model guidance still suggests that mainly Trinidad may see some rainfall from this system. Generally, less than 10 millimeters of rainfall is forecast on Monday across both islands. This is when the “active” weather from this wave is forecast to occur. Isolated areas, particularly Eastern and Southern parts of Trinidad, may see heavier showers with accumulations up to 20 millimeters. There is a low chance of a thunderstorm.

No severe weather is forecast. However, with locally heavy rainfall, which is possible, street flooding may occur. Additional updates will be posted closer to the date in another tropical update.

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the month of June. Though attention is usually placed on the Western Caribbean, Gulf of Mexico and the Western Atlantic, a few storms have developed east of Trinidad and Tobago during the month of June, most recently and notably – Tropical Storm Bret in 2017.

In June, we turn our eyes to the Western Caribbean 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.

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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