Back-to-Back Tropical Wave 24 & Tropical Wave 25 To Bring Showers, Thunderstorms Across T&T

There is no alert, watch or warning in effect for Trinidad and Tobago at this time as Tropical Wave 24 Moves Across the Islands.

What We Know

The axis of Tropical Wave 24 is now west of Trinidad and Tobago. Showers and thunderstorms are approaching T&T.  Most of the "active" weather is forecast to move across Southern and Central Trinidad, with additional showers and thunderstorms to develop across the island after midday. Credit: Weathernerds.org
The axis of Tropical Wave 24 is now west of Trinidad and Tobago. Showers and thunderstorms are approaching T&T. Most of the “active” weather is forecast to move across Southern and Central Trinidad, with additional showers and thunderstorms to develop across the island after midday. Credit: Weathernerds.org

The axis of Tropical Wave 24 is now west of Trinidad and Tobago, along 62W, between 5N to 20N. It has brought favorable upper-level divergence and low-level convergence, supporting showers and thunderstorms east of Trinidad.

High total precipitable moisture and low wind shear are present.

East Atlantic Tropical Update
East Atlantic Tropical Update

Tropical Wave 25, on the heels of TW24, axis is along 49/50W from 4-20N southward, moving west at 10-15 knots. Scattered showers prevail along the wave axis. This wave is forecast to move across T&T on Monday.

What We Expect

Impacts

The Takeaway: As we’ve been forecasting [Friday, Saturday] Showers are mainly forecast to occur across Southern, Central and Eastern Trinidad through midday. After midday, showers and thunderstorms are forecast to develop across much of Trinidad, producing locally heavy rainfall. Isolated gusty winds and street flooding possible.

This activity is forecast to subside by the late evening, with isolated showers interrupting partly to mostly cloudy skies. Showers and thunderstorms are forecast to occur again after midnight into Monday, lingering through the day.

Generally, widespread or scattered severe weather is not likely. Localized severe weather reports are possible, with locally (isolated) heavy rainfall.

GOES-East GEOCOLOR CIRA Satellite Imagery showing scattered convection (showers and thunderstorms) nearing Trinidad. Tropical Wave 24 has moved across T&T, forecast to bring showers and isolated thunderstorms today through tomorrow. Street/Flash Flooding, Gusty Winds possible. The heaviest rainfall and thunderstorms likely across Eastern and Southern Trinidad.

By midday, showers and thunderstorms are forecast to move across Trinidad from the southeast moving west-northwest. Street/Flash Flooding and gusty winds possible.

This activity is forecast to subside by late evening, with a few lingering showers interrupting a partly cloudy evening.

9:05 AM Sunday 21st July 2019 Radar Imagery from the Trinidad and Tobago Meteorological Service showing scattered showers southeast of Trinidad approaching the islands.
9:05 AM Sunday 21st July 2019 Radar Imagery from the Trinidad and Tobago Meteorological Service showing scattered showers southeast of Trinidad approaching the islands.

Based on the latest model guidance, intermittent showers and isolated thunderstorms are forecast to favor Eastern and Southern Trinidad on Sunday, gradually moving across Northern Trinidad and Tobago by the late afternoon.

Locally Heavy Rainfall & Flooding: Based on the latest model runs on Sunday morning, from Sunday (2:00 AM) through Tuesday (2:00 AM), generally, over the 48 hour period, models are in agreement of fewer than 15 millimeters across Western halves of Trinidad and Tobago and between 15-30 millimeters across the Eastern halves of both islands. Isolated rainfall totals in excess of 30 millimeters are possible across Eastern coastal Trinidad and Tobago. Much of the heaviest showers and thunderstorms are forecast to occur just offshore Eastern Trinidad.

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. Thunderstorms are likely to occur Sunday, after midday as well as on Monday.

Gusty Winds: Gusty winds, generally between 40 and 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.

High Wind Event Precautions
High Wind Event Precautions

Landslides: Though there is a low chance of landslides, heavy showers across the Northern Range may trigger landslides in landslide-prone areas. Particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur across both islands. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.

Why I May Not/Will Not See Constant Rainfall?

Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.
Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.

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.

Generally, because of winds associated with tropical waves, showers and thunderstorms tend to follow a west-northwest track, generally missing areas across Southwestern Trinidad and even Northwestern Trinidad – though activity due to local climatic effects such as daytime heating may trigger shower and thunderstorm development across these areas. See the below graphic for a simple explanation.

With these tropical waves (Tropical Wave 24 and Tropical Wave 25), mostly scattered showers are forecast. Hence, we are likely to see intermittent showers and thunderstorms, interrupting partly cloudy to overcast skies between Sunday and Tuesday.

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