One more tropical wave is set to move across Trinidad and Tobago this week, with another more than a week away. At this time, none are showing signs of organization, across the entire Atlantic Basin, tropical cyclone formation is not forecast over the next seven days.
What you need to know
— Tropical Wave 07: The axis of this tropical wave is located along 57W on Monday afternoon, moving west at 10-15 knots (18-27 KM/H). This tropical wave is forecast to move across T&T on Tuesday as it continues to interact with the Intertropical Convergence Zone (ITCZ), which remains across the country. A low-level trough embedded within the ITCZ is forecast to follow this wave on Thursday evening, bringing rainfall on Friday.
— Tropical Wave 08: This tropical wave has just moved off the African coast, located along 23W on Monday afternoon, moving west at 10 knots (18 KM/H). Forecast models indicate this wave is set to move across the region early next week.
— Hazards: Through Wednesday morning, and again from Thursday evening through Friday, periods of rain, moderate to heavy showers, and isolated to scattered thunderstorms are forecast to affect Trinidad and Tobago as a result of these tropical waves interacting with the Intertropical Convergence Zone. Flooding and landslide concerns will increase, particularly on Tuesday and again on Friday.
Tropical Wave 07
The seventh tropical wave analyzed by the National Hurricane Center is located approximately 420 kilometers east of Trinidad and Tobago, along 57W, and moving west at 10 knots (18 KM/H). The tropical wave is producing scattered showers and thunderstorms, mainly associated with the Intertropical Convergence Zone.
Across the wave axis, total precipitable water (TPW) values, which measure atmospheric moisture, are high, between 2.5 and 3 inches. Wind shear generally south of 11N ranges between 15 and 25 knots, with light shear, less than 15 knots, across Trinidad and Tobago.
Forecast models indicate favorable low-level and upper-level conditions as this tropical wave nears Trinidad and Tobago, particularly overnight tonight (Monday into Tuesday). This will lead to cloudiness, scattered showers, and isolated to scattered thunderstorms through Wednesday morning. Heavy rainfall is likely on Tuesday due to a saturated environment and favorable mid-level conditions, with high relative humidities and total precipitable water.
On Wednesday, a high-pressure ridge is forecast to briefly move in and remain present through Thursday, with a surge of Saharan Dust accompanying, but a low-level trough embedded within the ITCZ is forecast to move across the region (seen below), bringing rainfall across the country once more from Thursday evening through Friday night.
Tropical Wave 08
The eighth tropical wave analyzed by the National Hurricane Center is located well east of Trinidad and Tobago, along 23W, and moving west at 10 knots (18 KM/H). The tropical wave is producing scattered convection mainly along the southern portion of the wave axis where it meets with the Intertropical Convergence Zone.
This tropical wave is forecast to move across Trinidad and Tobago sometime early next week. With these large tropical waves, the axis tends to move across the area a day or so after the leading moisture arrives. Based on current guidance, the leading edge of moisture, associated with the ITCZ, is forecast to arrive across T&T on Sunday, with the wave moving across T&T Monday into Tuesday next week.
Not Every Tropical Wave Brings Severe Weather
Tropical waves vary in intensity as they travel westward across the Atlantic. This variability can be in the order of days or as short term as hours. Sometimes, you may see satellite imagery that shows heavy thunderstorms and deep convective activity east of Trinidad and Tobago during the late night and early morning, but by daybreak – nothing.
This is due to diurnal (daily) variations in convective showers whereby convection peaks overnight and wanes during the day for already occurring convective systems (i.e., not triggered by daytime heating).
Activity can be enhanced by its proximity to upper-level troughs and the ITCZ but can also be degraded by hostile upper-level conditions and Saharan Dust.
