Live Updates – Tropical Wave 20/21 & The ITCZ

Tropical Wave 20 is forecast to move across T&T on Monday with Tropical Wave 21 moving across on Tuesday, interacting with the ITCZ, day two of a three-day rainfall event across T&T. Heavy rainfall is possible on Monday and Tuesday, with scattered showers and isolated thunderstorms possible. Heavy rainfall may trigger street or flash flooding. Gusty winds up to and in excess of 55 KM/H possible, causing localized wind damages, downed trees, utility poles, and lines, as well as brief power outages. There are no alerts, watches, or warnings in effect from the TTMS. Live updates for this event have ended.

Isolated Rainfall Totals Up To 50 Millimeters Recorded Across T&T

12:00 AM Wednesday 8th July 2020

As forecast, much of Tuesday’s heavy showers and thunderstorms favored Western and Southern areas of both islands.

Across Southwestern Trinidad and Tobago, rainfall totals between 35 millimeters and 45 millimeters were recorded, with likely higher totals occurring. Heavy rainfall across Southwestern Trinidad triggered street and flash flooding.

Across the remainder of Trinidad, rainfall totals were higher near Western Coastal Trinidad, between 15 millimeters to 30 millimeters, while interior locations recorded generally less than 20 millimeters of rainfall.



Isolated Showers, Thunderstorms to Gradually Diminish Across Trinidad

4:15 PM Tuesday 7th July 2020

Conditions are settling across Trinidad, with isolated showers favoring Western areas of Trinidad.

Two isolated thunderstorms are slowly moving west towards Trinidad, forecast to bring increased cloudiness and possible rainfall.

However, activity forecast to settle by the evening across T&T.



Flooding Continues Across Barrackpore

2:30 PM Tuesday 7th July 2020

Reports of flooding across Barrackpore continues. While most roads are passable, traversing through flooded road ways are not recommended.



Isolated Showers, Thunderstorms Affecting Trinidad

2:25 PM Tuesday 7th July 2020

The axis of Tropical Wave 21 is west of T&T, as the ITCZ remains across the islands.

Isolated showers are affecting parts of Trinidad, with isolated thunderstorms favoring Western Coastal areas, moving west-northwest. This activity is forecast to gradually diminish by the evening.

Main Hazards: Locally heavy rainfall, street/flash flooding, reduced visibility, and gusty winds.



Fallen Tree Removed At Matura

12:45 PM Tuesday 7th July 2020



Flooding Still Ongoing Across Parts of Barrackpore

12:30 PM Tuesday 7th July 2020

Early morning showers and thunderstorms dumped up to 50 millimeters of rainfall across parts of Penal, Debe, and Barrackpore, triggering street and flash flooding across the area.

Flooding is ongoing across Barrackpore, with one roadway still impassable.



Resurgence of Showers, Thunderstorms Forecast This Afternoon

10:00 AM Tuesday 7th July 2020

The axis of Tropical Wave is now west of Trinidad and Tobago, while the ITCZ lingers across the islands.

Activity associated with the ITCZ has two peaks – between 12:00 AM to 6:00 AM, and again between 12:00 PM and 3:00 PM, with minimum activity during 5:00 PM through 8:00 PM.

Hence, as the ITCZ remains across T&T, with abundant moisture across the islands, cloudiness is forecast to build across Trinidad, with heavier showers and thunderstorms favoring Western and hilly areas of the island. Isolated showers are possible elsewhere.



Street/Flash Flooding Ongoing Across Barrackpore, Debe, Penal

6:00 AM Tuesday 7th July 2020

Street and flash flooding has been reported along the Penal Rock Road, with areas impassable as well as along the S.S. Erin Road. Heavy rainfall is on the decline across the area.



Heavy Showers, Thunderstorms Affect Southern Trinidad
Street/Flash Flooding Likely

5:00 AM Tuesday 7th July 2020

As forecast, a resurgence in showers and thunderstorms resulting from Tropical Wave 21 interacting with the ITCZ is ongoing across parts of Trinidad, lesser so Tobago after being affected by heavy showers earlier.

Heavy showers have been ongoing across Southwestern Trinidad over the last hour, with a new area of convection developing. Given the high flood hazard across the Penal-Debe-Barrackpore area, street/flash flooding is likely.

GOES-EAST GEOCOLOR/IR-13 Satellite Loop showing activity associated with the ITCZ and Tropical Wave 21 affecting Trinidad, Tobago and the Windward Islands. (NASA)
GOES-EAST GEOCOLOR/IR-13 Satellite Loop showing activity associated with the ITCZ and Tropical Wave 21 affecting Trinidad, Tobago and the Windward Islands. (NASA)


Street/Flash Flooding Likely Ongoing Across Tobago

2:05 AM Tuesday 7th July 2020

Over the last two hours, rainfall accumulations at Scarborough, Tobago have exceeded 30 millimeters, and increasing as heavy showers continue to affect the island.

With persisting heavy showers, street/flash flooding have become increasingly likely across the Central and Eastern areas of the island that have received the highest rainfall totals in a short time frame. Do not travel through flooded roadways!



Heavy Showers Affecting Tobago, Approaching Trinidad
Activity Associated With TW21, ITCZ Affecting Windwards

2:00 AM Tuesday 7th July 2020

The axis of Tropical Wave 21 remains east of T&T. However, activity ahead of the wave, as well as the ITCZ, has begun to affect T&T and the Windwards.

Through Tuesday, periods of showers, at times heavy, and isolated thunderstorms are forecast to interrupt partly to mostly cloudy skies. Conditions to gradually settle by the evening. Gusty winds, street/flash flooding possible.

Presently, as of 2:00 AM Tuesday, showers are moving across Tobago and parts of Southern and Central Trinidad.

Activity associated with Tropical Wave 21 and the Intertropical Convergence Zone is also affecting parts of St. Vincent and the Grenadines, St. Lucia and Barbados, with activity nearing Grenada. Locally heavy rainfall and gusty winds are forecast to accompany showers and thunderstorms, mainly north of Barbados, through Tuesday.

Activity associated with the ITCZ and Tropical Wave 21 moving across the Windward Islands, ahead of TW21's wave axis. (Weathernerds)
Activity associated with the ITCZ and Tropical Wave 21 moving across the Windward Islands, ahead of TW21’s wave axis. (Weathernerds)


Isolated 24-Hour Rainfall Totals Up to 25 Millimeters

12:00 AM Tuesday 7th July 2020

Tropical Wave 20 and the ITCZ produced periodic showers and isolated thunderstorms mainly across Trinidad on Monday.

Generally, across Trinidad, rainfall accumulations less than 15 millimeters were recorded, with isolated totals up to 25 millimeters in areas that experienced heavy downpours and isolated thunderstorms.

Note that higher rainfall accumulations likely occurred across areas where publicly reporting stations do not exist, such as parts of Southern and Eastern Trinidad.



Tropical Wave 21 – Development Not Expected

8:00 PM Monday 6th July 2020

Much of the activity associated with Tropical Wave 21 have diminished Monday evening, with chances of tropical cyclone formation over the next 48 hours and 5 days respectively near 0%.

According to the NHC’s 8:00 PM AST Tropical Weather Outlook, “A fast-moving tropical wave continues to produce disorganized showers and thunderstorms a few hundred miles east of the Windward Islands. This disturbance has become less organized today, and development is not expected. The wave is forecast to move through the Lesser Antilles on Tuesday and could produce locally heavy rainfall and gusty winds on some of those islands.

8:00 PM Monday 6th July 2020 Tropical Weather Outlook
8:00 PM Monday 6th July 2020 Tropical Weather Outlook


Showers, Thunderstorms Return to T&T After Lull In Activity

3:15 PM Monday 6th July 2020

Showers and thunderstorms are beginning to move across Trinidad and Tobago as forecast.

Heavier activity will initially favor southern and eastern areas, as showers and isolated thunderstorms move west-northwest.

Conditions to settle by the late evening, with a resurgence in activity overnight towards the early morning on Tuesday.



NHC on TW21: “Development is becoming unlikely.”

2:00 PM Monday 6th July 2020

Though favorable upper-level divergence and low-level convergence remain in place across Tropical Wave 21, with persisting convection, models are not enthusiastic about developing this system beyond a strong tropical wave. In fact, the system has not become more organized on Monday.

According to the NHC’s 2:00 PM AST Tropical Weather Outlook, “A fast-moving tropical wave continues to produce disorganized showers and thunderstorms a few hundred miles east of the Windward Islands. This disturbance has not become any better organized today, and development is becoming unlikely. The wave is forecast to move through the Lesser Antilles on Tuesday and could produce locally heavy rainfall and gusty winds on some of those islands.

2:00 PM Monday 6th July 2020 Tropical Weather Outlook
2:00 PM Monday 6th July 2020 Tropical Weather Outlook


Showers, Thunderstorms Approach T&T

1:45 PM Monday 6th July 2020

The Axis of Tropical Wave 20 is now west of T&T, based on characteristic wind shifts.

Over the next 1-2 hours, increased cloudiness, showers and thunderstorms are forecast to move across both Trinidad and Tobago as activity associated with TW20 and the ITCZ moves across the islands.

Heavier showers and thunderstorms are forecast to initially favor Southern and Eastern Trinidad, gradually moving west-northwest across both islands.

Locally heavy rainfall, gusty winds, street flooding, reduced visibility, and lightning possible.



Tropical Wave 20 Moves West, Additional Showers, Thunderstorms Forecast This Afternoon

12:15 PM Monday 6th July 2020

The Axis of Tropical Wave 20 is now west of T&T, based on characteristic wind shifts (from the east-northeast to the east to east-southeast) at Crown Point, Tobago, and Piarco, Trinidad.

Showers and isolated thunderstorms from this morning have now moved west of T&T. However, additional showers and thunderstorms are forecast this afternoon, across both islands.

Heavier activity to favor Trinidad, bringing gusty winds, heavy rainfall, and possible street flooding.



Showers, Isolated Thunderstorms Affect Trinidad

9:50 AM Monday 6th July 2020

Isolated to scattered showers and thunderstorms are developing across Trinidad, with heavier activity favoring coastal areas across the island.

The axis of Tropical Wave 20 is moving across the islands, interacting with the ITCZ. Showers and thunderstorms are forecast through the afternoon as low wind shear, neutral upper-level divergence, and low-level convergence remain in place.

Main Hazards: Heavy Rainfall, Gusty Winds, Street Flooding, Lightning



Hostile Conditions Affecting Tropical Wave 21

8:00 AM Monday 6th July 2020

Though favorable upper-level divergence and low-level convergence remain in place across Tropical Wave 21, with persisting convection, models are not enthusiastic about developing this system beyond a strong tropical wave.

According to the NHC’s 8:00 AM AST Tropical Weather Outlook, ” A tropical wave continues to produce disorganized showers and thunderstorms several hundred miles east of the Windward Islands. Some slight development of this system is possible today before environmental conditions become hostile for development on Tuesday. The wave is forecast to move through the Lesser Antilles on Tuesday and could produce locally heavy rainfall and gusty winds on some of those islands.

8:00 AM Monday 6th July 2020 Tropical Weather Outlook
8:00 AM Monday 6th July 2020 Tropical Weather Outlook


NHC: Low Chance of Formation

2:00 AM Monday 6th July 2020

Even with the burst of convection near the “center” of this tropical disturbance, Tropical Wave 21 still has low chances (10%) of tropical cyclone formation over the next 48 hours and 5 days respectively.

According to the NHC’s 2:00 AM AST Tropical Weather Outlook, “A strong tropical wave, centered about 650 miles east of the Windward Islands, is producing disorganized showers and thunderstorms. Some slight development of this system is possible today before environmental conditions become hostile for development on Tuesday. The wave is forecast to move through the Lesser Antilles on Tuesday and could produce locally heavy rainfall as well as gusty winds on some of those islands.

2:00 AM Monday 6th July 2020 Tropical Weather Outlook
2:00 AM Monday 6th July 2020 Tropical Weather Outlook


Tropical Wave 20 To Move Across T&T on Monday

1:00 AM Monday 6th July 2020

As of 1:00 AM, the axis of Tropical Wave 20 remains just east of Trinidad and Tobago, with convection inland Guyana and no ocean convection activity associated with the wave axis.

Coinciding with the anticipated flare-up of activity associated with the ITCZ, showers, and thunderstorms are forecast across T&T by the early to mid-morning, though brisk showers persist through the next few hours.

The Forecast: An active ITCZ interacting with Tropical Wave 20 is forecast to be present across Trinidad and Tobago, with scattered and isolated to scattered thunderstorms forecast across both islands. Activity is forecast to begin by the early to mid-morning, with thunderstorms possible by the late morning through the afternoon, favoring Trinidad.

Seas to remain moderate, with waves up to 2.0 meters in open waters. In sheltered areas, less than 1.0 meter. Note that in heavier showers or thunderstorms, seas may become locally choppy or rough. Air quality to be at good levels.

The main hazards would be locally heavy rainfall, reducing visibility, and localized wind damage from wind gusts associated with heavier showers or thunderstorms. 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.

Generally, between 5-15 millimeters possible across both islands, with higher totals across Central, Western and Southern areas between 15-30 millimeters. In isolated thunderstorm activity and prolonged heavy rainfall, totals up to 50 millimeters possible.

GOES-East IR Imagery showing little activity associated with Tropical Wave 20, just east of T&T. However, the ITCZ remains across both islands, with activity anticipated over the next 2-4 hours. (Weathernerds)
GOES-East IR Imagery showing little activity associated with Tropical Wave 20, just east of T&T. However, the ITCZ remains across both islands, with activity anticipated over the next 2-4 hours. (Weathernerds)


Increased Activity Associated With Tropical Wave 21

12:45 AM Monday 6th July 2020



Tropical Wave 21 Being Monitored For Development

8:00 PM Sunday 5th July 2020



Tropical Wave 20 Forecast To Move Across T&T On Monday

7:30 PM Sunday 5th July 2020

The axis of Tropical Wave 19 has brought the ITCZ across Trinidad this morning, with periodic showers across the island throughout the day and isolated thunderstorms.

As we move into tonight, a resurgence in activity is forecast after midnight, with scattered to widespread showers and isolated to scattered thunderstorms possible across both islands. Activity will also be enhanced by the passage of Tropical Wave 20 on Monday.

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


Three Tropical Waves, the ITCZ to affect T&T Sunday through Tuesday

Saturday 4th July 2020

Three back-to-back Tropical Waves are forecast to keep the ITCZ across T&T beginning Sunday through Tuesday, with the highest chances for rainfall and inclement weather occurring on Monday.



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