Adverse Weather Alert Cancelled by TTMS. Showers, Thunderstorms Remain in Forecast This Afternoon & Tomorrow.

As of 2:00 PM Tuesday 6th August 2019, mostly sunny skies are occurring across Southern and Eastern Trinidad, as well as Western Tobago. Mostly cloudy skies with isolated showers are occurring across Central, Northern and Northwestern Trinidad as well as Eastern Tobago. These showers are forecast to develop into t-storms.

Daytime heating, sea breeze convergence and increased moisture associated with Tropical Wave 32’s passage aiding in the development of showers across the region. heavier showers and the isolated thunderstorm are likely this afternoon. Street flooding, gusty winds possible in heavy showers and thunderstorms. The Adverse Weather Alert was cancelled by the Trindad and Tobago Meteorological Service at 1:39 PM.

What We Know

The axis of Tropical Wave 32 is well west of Trinidad and Tobago but it is still affecting the light winds and increased moisture across the region. Showers and thunderstorms are likely this afternoon. Street/flash flooding, gusty winds possible. Credit: Weathernerds.org
The axis of Tropical Wave 32 is well west of Trinidad and Tobago but it is still affecting the light winds and increased moisture across the region. Showers and thunderstorms are likely this afternoon. Street/flash flooding, gusty winds possible. Credit: Weathernerds.org

Tropical Wave 32 is located in the Central Caribbean Sea, along 68/70W, moving west at approximately 10 knots. Scattered moderate to strong convection is over the Caribbean Sea, south of Hispanola.

This tropical wave continues to affect the wind regime across the region, with light winds from the south to southeast across Trinidad and Tobago. This is allowing for slow-moving showers and isolated thunderstorms to develop, with heavier showers along the Northern Range.

High total precipitable moisture and minimal wind shear are present. In addition, favorable upper-level divergence and low-level convergence are present across T&T. Conditions are favorable for showers and thunderstorm development over the next few hours as sea breeze convergence and daytime heating act as triggers to initiate convective activity.

The Adverse Weather Alert by the Trinidad and Tobago Meteorological Service has been cancelled as of 1:39 PM Tuesday 6th August 2019. This is due to, “the threat of significant activity and accompanying impacts has now decreased. However, the chance of heavy showers and thunderstorm activity remains in the forecast for the next several days.”

Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert Cancellation on August 6th, 2019.

What We Expect (For T&T)

Impacts

The Takeaway: Isolated to scattered showers and thunderstorms are forecast by the late afternoon across Trinidad, with isolated activity across Tobago.

Activity is forecast to subside by the late evening into tonight, with isolated lingering showers. Similar to Tuesday, after a mostly hot and sunny day, showers and thunderstorms are forecast to develop again by the late morning through the late evening.

Activity is forecast to linger through Wednesday night as Tropical Wave 33 approaches the region.

Generally, widespread severe weather is not likely. Localized to scattered severe weather reports are possible, with heavy rainfall.

Presently, winds are from the east to south at low-levels. This overall wind regime is forecast to remain in place over the next several days. This overall wind regime dictates the forward speed (or lack thereof) of shower and thunderstorm activity and allows for heavy shower and thunderstorm development, focusing along Western Trinidad and along the Northern Range

Street/Flash Flooding and gusty winds possible continue to be possible through Thursday as periods of late morning through afternoon showers and thunderstorms persist across mainly Trinidad, but also Tobago.

This afternoon through the evening – isolated to scattered showers and isolated thunderstorms to favor the northern half of Trinidad and isolated showers across Tobago. Later this evening, showers are forecast to develop across the southern half of Trinidad, mainly southwestern areas.

Overnight – Isolated showers are possible, interrupting a mostly settled night across both islands. Early morning showers are possible across Trinidad, with heavier showers across southwestern Trinidad.

Wednesday – Similar conditions to Tuesday, early morning showers mainly across Trinidad are forecast to give way to mostly sunny skies. This will then give way to isolated to scattered showers and isolated thunderstorms across mainly Trinidad by the late morning through the afternoon. Isolated, intermittent showers possible into the night.

 2:00 PM Tuesday 6th August 2019 Radar Imagery from the Trinidad and Tobago Meteorological Service showing scattered showers and thunderstorms across Northern and Northwestern Trinidad.
2:00 PM Tuesday 6th August 2019 Radar Imagery from the Trinidad and Tobago Meteorological Service showing scattered showers and thunderstorms across Northern and Northwestern Trinidad.

Based on the latest model guidance, isolated to scattered showers and isolated thunderstorms are forecast to move across both islands, with heavier activity favoring much of Trinidad over the next several days, interrupting sunny skies.

Locally Heavy Rainfall & Flooding: Next 24 hours – Based on the latest model runs on Tuesday morning, from Tuesday afternoon (2:00 PM) through Thursday (2:00 AM), generally, over the 36 hour period, models are in agreement of fewer than 20 millimeters across of Trinidad and Tobago and between 20-40 millimeters across isolated areas of 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 associated with the ITCZ as it moves across the area over the next 24-36 hours.

Frequent Lightning: In addition, with thunderstorms, frequent lightning is likely.

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: 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 this tropical wave (Tropical Wave 32) and the ITCZ, mostly scattered showers are forecast. Hence, we are likely to see intermittent showers and thunderstorms, interrupting partly cloudy to overcast skies between Tuesday and Wednesday, particularly between 12:00 PM and 6:00 PM.

Temperatures

Last night’s minimum temperatures were a mild 24.3°C at Piarco, Trinidad, and 26.9°C at Crown Point, Tobago. Tonight’s minimum temperatures are forecast to be near 24°C at Piarco, Trinidad, and 26°C at Crown Point, Tobago.

Today’s maximum high temperatures across T&T are forecast to be near 33°C at Piarco, Trinidad and 32°C at Crown Point, Tobago. Tomorrow, similar maximum high temperatures are forecast. Heat indices may top at 37°C across Trinidad and 34°C across Tobago. The heat index is an index that combines air temperature and relative humidity, generating a “feel’s like” temperature.

Seas

Seas are forecast to remain moderate in open waters through the next day or so. Waves in open waters are forecast between 1.5 to 2.0 meters, particularly East of Trinidad and Tobago. In sheltered areas, seas to remain below 1.0 meters but choppy during heavy showers or thunderstorms. Winds are forecast to remain near 10-15 knots, from the south to southeast, at times from the east.

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