Tropical Update: First Tropical Wave of 2020 To Affect T&T By Mid-Week

Tropical Update Overview:
Tropical Storm Arthur – Tropical Storm Arthur slightly strengthens in the Western Atlantic, no threat to T&T.
Tropical Wave 01 – A weak tropical wave is forecast to traverse the Southern Windwards by Tuesday night through Wednesday. Increased moisture may fuel heavier showers and thunderstorms across T&T Wednesday through Friday. No widespread severe weather forecast.
Impacts to T&T – After midnight Tuesday into Wednesday, showers, and cloudiness are forecast with isolated to scattered showers, isolated thunderstorms, and periods of light to moderate rain. On Thursday and Friday, isolated to scattered showers and thunderstorms are possible during the late morning through the afternoon, favoring Northern and Western halves of Trinidad. No direct tropical threats to Trinidad and Tobago are forecast over the next week but locally heavy rainfall is possible during the latter half of the week, mainly during the intense afternoon showers and thunderstorms. Street flooding, flash flooding, gusty winds generally between 30-50 KM/H and occasionally in excess of 50 KM/H, landslides, and frequent lightning possible. A high-pressure system is forecast to bring settled conditions to the region on Saturday.

Before we dive into the Tropical Update, a few notes:

  • Tropical waves are a normal part of the rainy season.
  • Not every tropical wave will form into a tropical cyclone.
  • Weaker tropical waves produce 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 Storm Arthur

Tropical Storm Arthur continues north-northeastward as of the 5:00 PM Tropical Update. Credit: Weathernerds
Tropical Storm Arthur continues north-northeastward as of the 5:00 PM Tropical Update. Credit: Weathernerds

Tropical Storm Arthur, the 1st named tropical cyclone of the 2020 Hurricane Season, continues into the North Atlantic, maintaining strength. This marks the 6th year in a row a tropical cyclone has formed before June 1st, the official start of the Hurricane Season.

No threat to the Lesser Antilles, including T&T.

Tropical Wave 01

Activity associated with Tropical Wave 01 along 47W to 51W in the Atlantic. Credit: Weathernerds
Activity associated with Tropical Wave 01 along 47W to 51W in the Atlantic. Credit: Weathernerds

As of the 5:00 PM Tropical Update, the axis of Tropical Wave 01 is approximately along is along 47W to 51W, from 14N southward, moving westward 10-15 knots (18.5 KM/H to 28 KM/H). Scattered moderate convection from 04N-10N between 45W-51W is associated with this broad tropical wave.

This is the first tropical wave for the 2020 Hurricane Season, which is right on time as the first tropical waves for the hurricane season usually materialize during May.

Moderate to strong wind shear continues to limit persistent convection, but upper-level divergence and low-level convergence are allowing for isolated pockets of deep convection to develop.

Abundant low-level moisture is forecast, supporting cloudiness and isolated to scattered showers, with thunderstorms possible Wednesday through Friday. The passage of this tropical wave will bring the onset of the 2020 Wet Season. See below for details.

What does all of this mean for Trinidad and Tobago?

T&T's 5-Day Weather Forecast
T&T’s 5-Day Weather Forecast

Monday: A high-pressure system continues to dominate across the Lesser Antilles, allowing for mostly sunny, breezy, and hot conditions throughout the day. Low-level cloud patches will traverse T&T, bringing brisk isolated showers, accompanied by gusty winds up to 50 KM/H. Mostly settled conditions are forecast during the evening into the night, with the odd isolated showers.

Tuesday: During the first half of the day, the high-pressure system continues to remain dominant, allowing for mostly sunny, breezy, and hot conditions throughout the day. Low-level cloud patches will traverse T&T, bringing brisk isolated showers, accompanied by gusty winds up to 50 KM/H. By the late evening, moisture ahead of the axis of Tropical Wave 01 will begin to affect the Windward Islands, including T&T. Increased cloudiness and isolated showers are forecast by nightfall. Showers to favor Northern and Eastern areas of Trinidad and Tobago. Seas to remain moderate, with waves up to 2 meters in open waters.

Wednesday: The axis of Tropical Wave 01 is forecast to move across Trinidad and Tobago. Winds initially will be out of the east-northeast to east. Periods of light to moderate rain, isolated to scattered showers and isolated thunderstorms are forecast to affect Trinidad and Tobago throughout the day, with variably cloudy skies. Conditions are forecast to settle by the evening, with a resurgence of showers overnight. Locally heavy rainfall, particularly during heavy to violent showers and thunderstorms are possible, with gusty winds up to 55 KM/H. Seas to remain moderate, with waves up to 2 meters in open waters, but may become choppy during heavy showers and thunderstorms. Street/flash flooding and landslides are possible.

Thursday: The influence of Tropical Wave 01 will remain across Trinidad and Tobago, with winds from the east to the east-southeast. After a mostly sunny start to the day, lingering moisture in conjunction with sea-breeze convergence, daytime heating, and orographic effects will trigger showers and isolated thunderstorms to develop by the late morning through the afternoon, favoring the Northern and Western halves of Trinidad. Conditions to become settled by the late evening with isolated showers possible overnight. Locally heavy rainfall is possible with gusty winds up to 55 KM/H. Seas to remain moderate, with waves up to 2 meters in open waters, but may become choppy during heavy showers and thunderstorms. Street/flash flooding and landslides are possible.

Friday: The influence of Tropical Wave 01 will remain across Trinidad and Tobago, with winds from the east to the east-southeast. After a mostly sunny start to the day, lingering moisture in conjunction with sea-breeze convergence, daytime heating, and orographic effects will trigger showers and isolated thunderstorms to develop by the late morning through the afternoon, favoring the Northern and Western halves of Trinidad. Conditions to become settled by the late evening with isolated showers possible overnight. Locally heavy rainfall is possible with gusty winds up to 55 KM/H. Seas to remain moderate, with waves up to 2 meters in open waters, but may become choppy during heavy showers and thunderstorms. Street/flash flooding and landslides are possible.

Saturday: A high-pressure system regains dominance across Trinidad and Tobago, with a surge in Saharan Dust. allowing for mostly sunny, breezy, and hot conditions throughout the day. Low-level cloud patches will traverse T&T, bringing brisk isolated showers, accompanied by gusty winds up to 50 KM/H. Mostly settled conditions are forecast during the evening into the night, with the odd isolated showers.

Impacts This Upcoming Week

Winds: Sustained surface winds between 25 KM/H and 45 KM/H with gusts in excess of 55 KM/H are likely in heavy showers or thunderstorms across Trinidad and Tobago, particularly Wednesday through Friday.

With wind gusts in excess of 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, bringing down utility poles and lines.

High Wind Event Precautions
High Wind Event Precautions

Rainfall: Throughout the week, daily rainfall accumulations are forecast to be isolated totals of less than 10-20 millimeters, with in excess of 20-40 millimeters in isolated thunderstorms or heavy downpours. Daily rainfall accumulations may range between 15-35 mm on Wednesday through 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.

Frequent Lightning: In addition, with forecast thunderstorms, frequent lightning is likely. 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 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. Widespread showers mean that nearly all persons and areas may experience rainfall.

This week, isolated to scattered activity is forecast.

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

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the month of May. Though much of the points of origin are west or north of T&T as we move into the first month of the Hurricane Season, we still need to pay attention to some of these waves and the ITCZ, which have historically brought major flooding events to T&T, hence all low-pressure systems in the Atlantic should be closely monitored, as we do in the Tropical Update.
Tropical Cyclone Points of Origin during the month of May. Though much of the points of origin are west or north of T&T as we move into the first month of the Hurricane Season, we still need to pay attention to some of these waves and the ITCZ, which have historically brought major flooding events to T&T, hence all low-pressure systems in the Atlantic should be closely monitored, as we do in the Tropical Update.

Tropical Cyclone Points of Origin during the month of May. Though much of the points of origin are west or north of T&T as we move into the first month of the Hurricane Season, we still need to pay attention to some of these waves and the ITCZ, which have historically brought major flooding events to T&T, hence all low-pressure systems in the Atlantic should be closely monitored, as we do in the Tropical Update.

List of names for the 2020 Atlantic Hurricane Season, which will be updated each tropical update as new systems develop.
List of names for the 2020 Atlantic Hurricane Season, which will be updated each tropical update as new systems develop.
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