Tropical Update: Tropical Waves to Keep Rain In The Forecast This Weekend Across T&T

Image courtesy BrohavWeatherFax

Tropical Weather Update:
Tropical Wave 29: This tropical wave is located east of Trinidad and Tobago, forecast to begin affecting the islands by late Saturday into Sunday. Favorable upper level conditions may support heavy showers and thunderstorms, particularly on Sunday. Much of the activity is forecast to move north of T&T, but severe weather is possible. Street/Flash Flooding, gusty winds may occur.
Tropical Wave 30: This tropical wave is located in the Central/Eastern Atlantic, well east of Trinidad and Tobago. It is forecast to move across T&T and the Lesser Antilles on Monday into Tuesday, increasing shower chances across T&T, but much of the showers and thunderstorms associated with this wave is forecast to move across the Leewards, well north of T&T. Street/Flash Flooding, gusty winds may occur, particularly across the Leewards.
Tropical Wave 31: This tropical wave is located in the far Eastern Atlantic. Though there is no operational model support for tropical cyclone development, nor is it being actively monitored by the National Hurricane Center, ensamble models are showing a non-zero chance of development. This wave is forecast to move across the Lesser Antilles late next week. It is too soon to tell what impacts this may bring to T&T.
Tropical Wave 32: This tropical wave has not moved off the African Coast, but models are showing a brief window for development just after entering the Eastern Atlantic, but remaining a tropical wave as it nears the Lesser Antilles next weekend. Again, it is too soon to tell what impacts this may bring to T&T.
No tropical cyclone development is forecast for the next 5 days across the North Atlantic Ocean according to the National Hurricane Center.

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 29

Tropical Wave 29, in the Central Atlantic, along 46W. This wave is forecast to move across the Lesser Antilles on Sunday but will begin to affect Trinidad and Tobago on Saturday, through Monday. Showers, periods of rain and thunderstorms are all possible during this 72 hour time frame. Credit: Weathernerds.org

Tropical Wave 29 is located in the Central Atlantic, along 46W, 18N southward, 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 6:00 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 possible on Saturday, mainly on Sunday across both islands.

This wave has no operational model support for tropical cyclone formation at this time. Much of the heaviest showers and thunderstorms are forecast to remain north of T&T based on the latest model guidance.

What We Expect

Impacts

During the first half of Saturday, mostly sunny and continuing hazy skies are likely across both islands, with hot conditions persisting.

Based on the latest model guidance, intermittent showers are forecast to begin during the second half of Saturday and continue throughout the day, with periods of rain and thunderstorms favoring Trinidad, interrupting cloudy skies. These conditions are forecast to persist 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.

This wave is forecast to bring the ITCZ across the region over the weekend. The ITCZ, coupled with favorable upper-level conditions along the western periphery of an upper-level anti-cyclone centered juts east of the islands, will support deep convective activity.

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. Tropical Wave 30 is forecast to begin affecting T&T by late morning.

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 Sunday across Trinidad. Gusty winds are also possible, up to 50 KM/H, mainly near heavy shower and thunderstorm activity.

Locally Heavy Rainfall & Flooding: Based on the latest model runs on Friday evening from Saturday (2:00 AM) through Tuesday (2:00 AM), generally, over the 72 hour period, models are in agreement of up to 25 millimeters across Western halves of Trinidad and Tobago and between 25-45 millimeters across the Eastern halves of both islands. Isolated rainfall totals up to 55 millimeters are possible across parts of Trinidad.

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, becoming more scattered on Sunday.

Gusty Winds: Gusty winds, generally up to 50 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 50 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: 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?

Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.
Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.

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.

Tropical Wave 30

 Tropical Wave 30, in the Central Atlantic, along 36/37W. This wave is forecast to move across the Lesser Antilles on Tuesday but will begin to affect Trinidad and Tobago by late Monday. Much of the heavier showers and thunderstorms are forecast to remain north of T&T. Credit: Weathernerds.org
Tropical Wave 30, in the Central Atlantic, along 36/37W. This wave is forecast to move across the Lesser Antilles on Tuesday but will begin to affect Trinidad and Tobago by late Monday. Much of the heavier showers and thunderstorms are forecast to remain north of T&T. Credit: Weathernerds.org

Tropical Wave 30 is located in the Central Atlantic, along 36/37W, 18N southward, moving west at approximately 15 knots. This tropical wave is forecast to begin affecting Trinidad, Tobago, and the Southern Windwards by late Monday into Tuesday of next week based on the latest information as of the 6:00 PM Tropical Update.

Much of the stronger showers and thunderstorms are forecast to remain north of Trinidad and Tobago through the period.

Across Trinidad and Tobago, late morning through afternoon showers and thunderstorms are likely, but no widespread significant weather is forecast at this time. These showers are forecast to interrupt partly cloudy skies.

This wave has no operational model support for tropical cyclone formation at this time. Reiterating, much of the heaviest showers and thunderstorms are forecast to remain north of T&T based on the latest model guidance.

Tropical Wave 31 & 32

Tropical Wave 30, in the Far Eastern Atlantic, along 21/22W. This wave is forecast to move across the Lesser Antilles late next week, but it is too soon to tell any specific impacts across the region. Credit: Weathernerds.org

Tropical Wave 31 is located in the Far Eastern Atlantic, along 21/22W, 18N southward, moving west at approximately 15 knots. This tropical wave is forecast to move across the Lesser Antilles late next week.

Disorganized showers and thunderstorms are occurring near the wave axis, with some noticeable spin. Significant development of this system appears unlikely low sea-surface temperatures and unfavorable upper-level winds while this wave moves westward over the next several days.

EMCWF (EPS) Ensemble Model Runs for tropical waves in the Atlantic Ocean. Credit: Alan Barammer

As of 6:00 PM, the National Hurricane Center is not actively monitoring this wave for tropical cyclone development. However, this system presently has quite a bit of spin (vorticity) associated with it, as well as strong winds (54 KM/H) associated with its showers and thunderstorms.

Further east, a tropical wave that hasn’t been officially designated by the National Hurricane Center, nor has it hit the Atlantic waters, has caught our attention as models are hinting at some brief development early next week but quickly returning to tropical wave status. Stay updated with the National Hurricane Center for the official word on these waves.

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 in the immediate future.

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.

2019 Atlantic Hurricane Season Names
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