Tropical Weather Update:
— Tropical Wave 27: This tropical wave is located east of Trinidad and Tobago, forecast to move across the Lesser Antilles on Thursday. A dry mid-level atmosphere is forecast to persist, inhibiting showers. No significant rainfall is forecast, but we can expect isolated to scattered showers, with the odd thunderstorm favoring SW Trinidad interrupting mostly sunny skies across T&T, on Thursday. A mild surge of dust is forecast following the passage of this wave.
— Tropical Wave 28: This tropical wave has been dropped from the National Hurricane Center’s surface analysis as the wave has merged with Tropical Wave 27 to its west.
— Tropical Wave 29: This tropical wave is forecast to begin affecting Trinidad and Tobago on Saturday through Monday. The heaviest activity, based on latest model guidance, is forecast on Saturday across Trinidad and Sunday across Tobago. Periods of showers, some becoming heavy, as well as rain and thunderstorms are in the forecast. Severe weather is possible. Street/Flash Flooding, gusty winds may occur.
— Gulf of Mexico Area of Interest: The National Hurricane Center is monitoring a weak area of non-tropical low-pressure in the Gulf of Mexico. Low chances of development.
Before we dive into the Tropical Updates on the tropical waves, a few notes:
- Tropical waves are a normal part of the rainy season.
- Not every tropical wave will form into a tropical cyclone.
- Tropical waves at the beginning of the Hurricane Season are typically weak, producing more rainfall across Eastern parts of the islands with mostly cloudy conditions and a few showers across western parts of the islands.
- Rainfall will be more isolated and intermittent with weaker tropical waves that do not have ITCZ or upper-level support.
- Saharan Dust may weaken tropical waves.
You can read more about the weather associated with Tropical Waves, as well as what to expect as these waves move through the region below.
Tropical Wave 27 & 28
Tropical Wave 28 has merged with Tropical Wave 27. No further updates as it has been dropped from the National Hurricane Center’s surface analysis as of 18Z Wednesday 24th July 2019 and today’s Tropical Update.
Tropical Wave 27’s axis is located along 56-57W, between 3N-23N, moving westward at 15 knots. A mild surge of moisture and marginal instability is supporting shallow convection, mainly north of Trinidad and Tobago, across the Leewards. This wave is forecast to bring partly to mostly cloudy skies to islands north of Trinidad and Tobago, with brisk, isolated to scattered showers. No significant rainfall forecast.
This wave is forecast to move across T&T on Thursday, with much of the active weather occurring north of T&T. Isolated heavy showers and thunderstorms are possible, particularly on Thursday, interrupting sunny skies. Street flooding may be possible in heavy downpours. No significant rainfall or widespread severe weather is forecast.
Tropical Wave 29
Tropical Wave 29 is located in the Eastern Atlantic, along 32W, between 28N and 2N, moving west at approximately 15 knots. This tropical wave is forecast to begin affecting Trinidad, Tobago, and the Southern Windwards on Saturday, through Monday of next week based on the latest information as of the 8:00 PM Tropical Update.
A deep plume of tropical moisture is forecast to move across the Eastern Caribbean resulting from this wave, with forecast low-level convergence ahead of the axis of this wave.
Across Trinidad, heavy showers, thunderstorms and periods of rain are likely on Saturday, while similar conditions are forecast across Tobago, but mainly on Sunday.
This wave has no model support for tropical cyclone formation at this time.
What We Expect
Based on the latest model guidance, intermittent showers are forecast to begin after 12:00 AM Saturday and continue throughout the day, with periods of rain and thunderstorms favoring Trinidad, interrupting cloudy skies. Conditions are forecast to become mostly settled by the late evening, with showers forecast again after midnight into Sunday.
On Sunday, heavier showers and possible thunderstorms are forecast to favor the Northern half of Trinidad and Tobago, but a similar pattern to Saturday is possible, becoming settled by the late evening.
Showers are forecast to become more isolated on Monday, interrupting partly cloudy skies. A few showers may become heavy and develop into thunderstorms, favoring Western parts of Trinidad.
Generally, widespread or scattered severe weather is not likely. Localized severe weather reports are possible, with elevated rainfall accumulations. Street/Flash flooding is possible, particularly on Saturday across Trinidad. Gusty winds are also possible, up to 55 KM/H.
Locally Heavy Rainfall & Flooding: Based on the latest model runs on Wednesday evening from Saturday (2:00 AM) through Tuesday (2:00 AM), generally, over the 72 hour period, models are in agreement of up to 30 millimeters across Western halves of Trinidad and Tobago and between 30-50 millimeters across the Eastern halves of both islands. Isolated rainfall totals up to 75 millimeters are possible across Eastern coastal Trinidad and 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, based on the above-mentioned forecast rainfall totals.
Frequent Lightning: In addition, with thunderstorms, frequent lightning is likely. Thunderstorms are possible across all three days, generally remaining fairly isolated.
Gusty Winds: Gusty winds, generally up to 55 KM/H are possible Gusty winds are most likely prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 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.
Landslides: Though there is a low chance of landslides, heavy showers across the Northern Range may trigger landslides in landslide-prone areas. Particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur across both islands. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.
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.
Generally, because of winds associated with tropical waves, showers and thunderstorms tend to follow a west-northwest track, generally missing areas across Southwestern Trinidad and even Northwestern Trinidad – though activity due to local climatic effects such as daytime heating may trigger shower and thunderstorm development across these areas. See the below graphic for a simple explanation.
With Tropical Wave 29, mostly scattered activity is forecast. Hence, we are likely to see intermittent showers and thunderstorms, interrupting partly cloudy to overcast skies, particularly Saturday and Sunday.
Area of Interest in the Gulf of Mexico
Disorganized showers and thunderstorms stretching across portions of the northern and central Gulf of Mexico are associated with a frontal boundary and a weak area of low pressure. Significant development of this system appears unlikely due to dry air and unfavorable upper-level winds while the disturbance drifts northward during the next couple of days.
Chances of development remain low, at 10% over the next 48 hours and 10% over the next 5 days.
Although unlikely, if this system develops into a named tropical cyclone, it will be named Chantal and will be no threat to Trinidad, Tobago and the Lesser Antilles.
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.