Tropical Update: Two Tropical Waves East of T&T

Tropical Update Overview:
Tropical Wave 32 – A tropical wave has moved across T&T on Saturday, dragging the ITCZ northward. This wave is forecast to continue moving west with no further impact to T&T.
Tropical Wave 33 – A large, tilted tropical wave is in the Central Atlantic, forecast to affect T&T late Tuesday into Thursday due to its large moisture field. Saharan Dust will limit shower and thunderstorm activity. Locally heavy rainfall possible on Wednesday and Thursday.
Tropical Wave 34 – A tropical wave in the East Atlantic is being monitored for tropical cyclone formation over the next 5 days, with low chances of development. While it is too soon to tell what impacts this may bring, much of the stronger winds and weather is forecast to remain north of T&T based on longer-range models.

Total Precipitable Water Imagery showing the Tropical Waves (analyzed by the National Hurricane Center, Weather Prediction Center, and TTWC) that exist east of Trinidad and Tobago.

Impacts to T&TThere are no direct tropical threats facing T&T over the next 5 days, at this time. A dry mid- and upper-level atmosphere will limit deep convective activity. However, isolated to scattered areas of heavy rainfall, favoring Trinidad on Wednesday and Thursday are forecast. Showers and thunderstorms may reduce visibility and produce gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.

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 Wave 31

Tropical Wave 32 is analyzed from 16N, along 64W. Most of the convective activity is associated with the ITCZ north of T&T. (Weathernerds)
Tropical Wave 32 is analyzed from 16N, along 64W. Most of the convective activity is associated with the ITCZ north of T&T. (Weathernerds)

As of the 11:00 PM Tropical Update, the 32nd tropical wave for the 2020 Atlantic Hurricane Season is located from 16N, along 64W based on our analysis. The wave axis is moving westward around 10 to 15 knots (18 to 27 KM/H).

This tropical wave and the ITCZ affected Trinidad and Tobago on Saturday, producing heavy rainfall across both islands. No further impacts are anticipated.

Tropical Wave 32

Tropical Wave 33 is analyzed further east from 20N southward along 35W to 42W, with scattered moderate and isolated strong convection from 02N to 06N between 38W and 44W, where the wave interacts with the ITCZ. (Weathernerds)
Tropical Wave 33 is analyzed further east from 20N southward along 35W to 42W, with scattered moderate and isolated strong convection from 02N to 06N between 38W and 44W, where the wave interacts with the ITCZ. (Weathernerds)

As of the 11:00 PM Tropical Update, the 33rd tropical wave for the 2020 Atlantic Hurricane Season is located from 20N southward along 35W to 42W, based on our analysis. The wave axis is moving westward around 15 knots (27 KM/H).

This wave has a large area of moisture, as seen on precipitable water imagery. However, Saharan Dust and an unfavorable atmosphere has limited persistent showers or thunderstorms associated with the wave.

Models show that this wave and much of its associated moisture will affect T&T beginning late Tuesday, with peak activity between Wednesday and Thursday. See below for details.

Tropical Wave 33

Tropical Wave 34 is analyzed from 13N southward, at 24W. This tropical wave is being monitored for tropical development. (Weathernerds)

As of the 11:00 PM Tropical Update, the 34th tropical wave for the 2020 Atlantic Hurricane Season analyzed from 13N southward, along 24W. The wave axis is moving westward around 5 to 10 knots (9 to 18 KM/H).

Scattered moderate isolated strong convection is noted from 07N to 12N between 19W and 25W. This wave is forecast to move into a marginally supportive environment this week, with models showing some indication of organization as the wave moves into the Central Atlantic.

Tropical Weather Outlook from the National Hurricane Center, giving Tropical wave 34 low chances of tropical cyclone formation over the next 5 days as it moves into the Central Atlantic
Tropical Weather Outlook from the National Hurricane Center, giving Tropical wave 34 low chances of tropical cyclone formation over the next 5 days as it moves into the Central Atlantic

However, no models bring an organized tropical cyclone into the Lesser Antilles next weekend, keeping this wave as a strong tropical wave.

According to the National Hurricane Center’s tropical weather outlook at 8:00 PM, “Showers and thunderstorms located a few hundred miles south of the Cabo Verde Islands are associated with a westward-moving tropical wave. Some slow development of this system is possible over the next few days as it crosses the tropical eastern Atlantic. By the middle of next week, environmental conditions are expected to become less favorable for development.

It is still too soon to forecast exactly what impacts, if any this wave may bring to the islands. See below for our 5-day forecast.

What does all of this mean for Trinidad and Tobago?

Remainder of Saturday: Mostly settled with partly cloudy skies.

Seas forecast to be moderate, with waves up to 1.5 meters in open waters. In sheltered areas, below 1.0 meter. No adverse weather impacts forecast, as a dry mid-level and upper-level environment is now in place.



Sunday – A surge of Saharan Dust and a dry mid- and upper-level environment is forecast to remain in place as a ridge of high pressure strengthens following the passage of Tropical Wave 32. The ITCZ is forecast to drift southward of T&T.

AM – Mostly settled conditions are forecast to persist into the morning, with showers generally remaining in our offshore waters and favoring eastern areas of both islands. A mostly hot and sunny morning is anticipated, somewhat hazy due to mild concentrations of Saharan Dust. By the late morning, partly cloudy skies may give way to a few isolated showers favoring Trinidad, with the low chance of heavier showers or thunderstorms.

PM – Partly cloudy skies may be interrupted by isolated to scattered showers or isolated thunderstorms favoring northern and eastern of Trinidad as well as Tobago. Isolated thunderstorms are also possible across both islands due to an anticipated flare-up of the ITCZ. These showers will bring some much-needed cooling to a mostly hot day. A mostly settled evening is forecast, barring the odd, isolated shower.

Seas forecast to be slight to moderate, with waves between 1.0 to 1.5 meters in open waters. In sheltered areas, below 1.0 meter, but becoming choppy in showers and thunderstorms. Air quality is forecast to decrease to moderate levels at times.

The main hazards include isolated heavy rainfall, favoring the Western half of Trinidad, reducing visibility, and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.


Election Day 2020


Monday – The ITCZ is forecast to linger just south of Trinidad. Lingering moisture is forecast to fuel isolated showers and thunderstorms from the late morning through the afternoon, mainly across Southern and Western areas.

AM – Mostly settled conditions are forecast to persist into the morning, with showers generally remaining in our offshore waters and favoring eastern areas of both islands. A mostly hot and sunny morning is anticipated, somewhat hazy due to mild concentrations of Saharan Dust. By the late morning, partly cloudy skies may give way to a few isolated showers favoring Trinidad, with the low chance of heavier showers or thunderstorms.

PM – Partly cloudy skies may be interrupted by isolated showers or isolated thunderstorms favoring western and hilly areas of Trinidad. Isolated showers are also possible across Tobago. These showers will bring some much-needed cooling to a mostly hot day. A mostly settled evening is forecast, barring the odd, isolated shower. Moisture ahead of Tropical Wave 33 may being to fuel isolated showers, favoring eastern areas of both islands by the late night.

Seas forecast to be slight to moderate, with waves between 1.0 to 1.5 meters in open waters. In sheltered areas, near calm. Air quality is forecast to decrease to moderate levels at times.

The main hazards include highly isolated heavy rainfall, favoring the Western half of Trinidad, reducing visibility, and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.


Tuesday – During the day, moisture will begin to move across T&T ahead of Tropical Wave 33. However, a surface to mid-level high-pressure system will continue to be the dominant feature over T&T until nightfall.

AM – Isolated showers are possible after midnight through the early morning. By daybreak, mostly hot and sunny conditions are forecast to give way to partly cloudy skies by the late morning. A few isolated showers favoring Trinidad, with the low chance of heavier showers or thunderstorms, are possible by midday.

PM – Partly cloudy skies may be interrupted by isolated showers or isolated thunderstorms favoring Trinidad. Isolated showers are also possible across Tobago. These showers will bring some much-needed cooling to a mostly hot day. A mostly settled evening is forecast, barring the odd, isolated shower. An increase in showers is forecast by the late-night, favoring Eastern Trinidad and Tobago continuing into Wednesday.

Seas forecast to be slight to moderate, with waves between 1.0 to 1.5 meters in open waters. In sheltered areas, near calm. Air quality is forecast to decrease to moderate levels at times.

The main hazards include highly isolated heavy rainfall, favoring the Western half of Trinidad, reducing visibility, and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.


Wednesday and Thursday – Moisture associated with Tropical Wave 33 will be moving across Trinidad and Tobago, with the axis of the wave moving across the islands by the late night.

AM – Overnight showers are forecast to spread across Trinidad and Tobago through the morning with partly to mostly cloudy skies. By the late morning, isolated to scattered showers and isolated thunderstorms into the afternoon.

PM – Partly cloudy skies forecast to be interrupted by isolated to scattered showers and isolated thunderstorms favoring Trinidad. Activity is forecast to subside by the evening, but scattered showers are forecast to return overnight due to the ITCZ.

Seas forecast to be slight to moderate, with waves between 1.0 to 1.5 meters in open waters. In sheltered areas, near calm.

The main hazards include isolated heavy rainfall, favoring eastern areas of Trinidad and Tobago, reducing visibility, and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage.

Note that with weak winds, with sea breeze convergence, heat, and orographic effects acting as triggers for shower and thunderstorm development.

Possible Impacts Over Next 5-7 Days

There are no tropical systems that pose a direct threat to T&T over the next week, as of today’s tropical update. However, heavy rainfall is possible.

Winds

Sustained surface winds will be weak, generally below 25 KM/H during the afternoon at its peak. However, Gusts up to and in excess of 55 KM/H possible in heavy showers or thunderstorms across Trinidad and Tobago.

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

Sunday through Monday: Conservatively, little to no rainfall is forecast, with isolated totals up to 55 millimeters across both islands.

Generally, late Tuesday through Thursday,: Between 10-15 millimeters are forecast, with isolated totals between 20-35 millimeters possible. In slow-moving downpours or thunderstorms, up to 50 millimeters possible.

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.

Isolated to scattered activity is forecast through the forecast period.

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

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the first through third weeks of August.

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