Tropical Weather Update:
— Tropical Wave 17: This tropical wave, after producing some scattered showers and thunderstorms across Trinidad and Tobago over the last 48 hours, is now well west of T&T, with no additional impacts forecast. Saharan Dust now moves across the islands behind the passage of this wave.
— Tropical Wave 18: A strong tropical wave is located in the Central Atlantic. This wave is presently embedded in the ITCZ. It is not forecast to develop into a tropical cyclone. This wave is forecast to move across the Southern Windwards and the French Antilles, including T&T on Friday into Saturday. Severe weather is possible.
— Tropical Wave 19: This tropical wave is located in the far Eastern Atlantic, forecast to move across Trinidad, Tobago and the remainder of the Southern Windwards on Sunday into Tuesday. An increase in showers with possible thunderstorms expected but based on present model guidance, no significant rainfall is forecast. This wave is forecast to keep the ITCZ across the region through next week, maintaining the typical wet season pattern across T&T.
— Tropical Wave 20: This tropical wave is located in the far Eastern Atlantic, forecast to move across T&T beginning on Wednesday through Thursday of next week. It is too soon to tell definitive impacts, but as typical with tropical waves, an increase in cloudiness, showers, and thunderstorms are likely.
— Invest 92L: An area of low pressure is forecast to become the next named tropical cyclone of the 2019 Atlantic Hurricane Season. This system is of no threat to Trinidad, Tobago, and the Eastern Caribbean. However, residents and interests along the U.S. Gulf Coast between the Upper Texas Coast and the Florida Panhandle should remain vigilant to the latest forecast from their local meteorological offices and the National Hurricane Center. A tropical depression may form later today (Wednesday) or early Thursday. 10:30 AM Update: The National Hurricane Center will begin issuing advisories on Potential Tropical Cyclone 10 at 11:00 AM.
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 weather associated with Tropical Waves, as well as what to expect as these waves move through the region below.
Tropical Wave 17
This tropical wave brought showers and thunderstorms across Trinidad and Tobago over the last 24 hours, with sporadic reports of street/flash flooding.
Tropical Wave 18
The axis of this wave extends its axis along 49W from 13N southward, moving west at 15 knots. According to the National Hurricane Center, “scattered showers and thunderstorms are seen within 150 nautical miles of the wave axis from 07N-11N. Enhanced showers and thunderstorms are likely for the Lesser Antilles and Eastern Caribbean Friday into Saturday.“
This wave is embedded within the ITCZ. It is forecast to bring a surge of moisture across Trinidad, Tobago and the Windwards by Friday into Saturday, dragging the ITCZ over T&T. Gusty winds are forecast to follow this wave, with moderate seas of waves between 2.0 and 2.5 meters in open waters beginning late Saturday through Tuesday.
On Friday morning through the first half of Saturday, Trinidad and Tobago will see an increase in cloudiness, showers, and thunderstorms. Much of the heaviest activity is forecast to occur on Friday, with moderate to rough seas, street flooding, gusty winds, and landslides. Note that this wave will be similar to Tropical Wave 17, as much of the heaviest showers and thunderstorms move north of T&T.
What To Expect With Tropical Wave 18
Note: Street/Flash flooding, frequent lightning, gusty winds, landslides/mudslides are all possible beginning Friday through Saturday. In addition, locally heavy showers and thunderstorms may produce isolated areas, up to 60 millimeters of rainfall, across the Windward Islands.
Possible Impacts to Trinidad and Tobago
Locally Heavy Rainfall & Flooding: Based on the 0Z and 6Z model runs on Wednesday, from Friday (2:00 AM) through Sunday (2:00 AM), generally, over the 48 hour period, models are in agreement of fewer than 20 millimeters across Western halves of Trinidad and Tobago and between 20-40 millimeters across the Eastern halves of both islands. Isolated rainfall totals up to 50 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.
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.
Landslides: In landslide-prone areas, particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.
Tropical Wave 19
The axis of Tropical Wave 19 wave extends along 37W, south of 16N and is moving westward at 10-15 knots as of the 10:00 AM Tropical Update. No significant surge of moisture or convection is noted with this tropical wave. It is forecast to move across T&T Sunday into Tuesday.
While the wave itself is not forecast to be a significant rainmaker, it will drag the ITCZ across T&T by Tuesday, keeping a fairly wet pattern in place through next week as deep tropical moisture remains across T&T. Note, this is typical of the wet season. Generally, daily (24-hour) rainfall accumulations between 10-30 millimeters are possible across both islands, with totals nearing the upper end of the range favoring Eastern Trinidad.
Tropical Wave 20
The axis of Tropical Wave 20 wave extends along 26W, south of 15N and is moving westward at 15-20 knots as of the 10:00 AM Tropical Update. This wave is forecast to begin affecting Trinidad, Tobago and the Windwards by Tuesday next week, while its axis forecast to move across on Wednesday 17th July 2019, a week away.
While it is too soon to tell definitive impacts of this wave, because of its wide moisture envelope, notable spin (vorticity) and widespread cloudiness and showers – this wave will likely bring at least 48-72 hours (through Friday of next week) of intermittent showers and thunderstorms across the Windwards as it progresses westward.
With regards to development, none of the top three models for tropical cyclogenesis support development at this time, keeping this a strong tropical wave as it moves across the Atlantic. Strong wind shear is present and is forecast to continue to be present ahead of this wave over the next several days, inhibiting attempts to organize. The spin on this wave is also forecast to diminish as it progresses westward.
Daily rainfall totals beginning Monday next week, through Friday are forecast to be between 10-30 millimeters, with totals on the upper end of this range favoring Eastern Trinidad. Note that locally higher amounts may be possible resulting from persistent heavy showers and thunderstorms.
Between Monday and Friday of next week, rainfall totals from both waves and the ITCZ, based on present analysis as of the 10:00 AM Tropical Update, are forecast to be between 20-30 millimeters across Western halves of Trinidad and Tobago, 50-70 millimeters across Eastern halves of T&T and isolated totals up to 120 millimeters particularly along Coastal Eastern Trinidad, making this a potential flooding threat. In addition, there is the threat of gusty winds.
Because of the long range of these waves, there is considerable uncertainty in the exact timing of showers, thunderstorms, and locations that may receive heavier rainfall totals. Expect additional details in a subsequent tropical update.
High Chance of Tropical Cyclone Formation in the Gulf of Mexico, No Threat to T&T
A broad low-pressure area located over the northeastern Gulf of Mexico about 100 miles south-southwest of Apalachicola, Florida, is producing widespread cloudiness and disorganized showers and thunderstorms. Environmental conditions are conducive for development of this system, and a tropical depression is expected to form late today or Thursday while the low moves slowly westward across the northern Gulf of Mexico.
An Air Force Reserve Unit reconnaissance aircraft is scheduled to investigate the disturbance this afternoon. This system could produce storm surge and tropical- storm- or hurricane-force winds across portions of the Louisiana, Mississippi, and Upper Texas coasts later this week, and interests there should closely monitor its progress. In addition, this disturbance has the potential to produce very heavy rainfall from the Upper Texas Coast to the Florida Panhandle.
For more information, please see the products issued by your local weather forecast office and the NOAA Weather Prediction Center.
As of the 8:00 AM Tropical Weather Outlook, this system has a high chance of tropical cyclone formation over the next 48 hours to 5 days, at 90%.
For more details on the system, the latest information can be found at the National Hurricane Center.
If this system forms, it will be of NO threat to Trinidad, Tobago, and the Eastern Caribbean.
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.