Tropical Wave 17 Forecast: Showers, Thunderstorms Likely During First Half of Tuesday. Saharan Dust to Follow.

Key Messages:
— Tropical Wave 17 is forecast to bring showers, thunderstorms after midnight (12:00 AM Tuesday) to both Trinidad and Tobago, subsiding by the early afternoon on Tuesday.
— Much of the heavier showers, thunderstorms to affect Tobago, Northeastern Trinidad. Southwestern and Western Trinidad may not see frequent or persistent rainfall throughout tonight due to the WNW motion of showers and thunderstorms.
— Gusty winds up to 60 KM/H are possible. Locally heavy rainfall, favoring Northeastern and Coastal Eastern Trinidad, as well as Tobago may trigger street and even flash flooding. Landslides and downed trees are possible in elevated areas. Severe weather is possible. Much of the “inclement” weather is forecast to occur overnight into early Tuesday.
— A mild surge of Saharan Dust is forecast to follow late Tuesday into Wednesday, reducing air quality to moderate.
As of 7:00 PM Monday 8th July 2019 – There are no alerts, watches or warnings in effect for T&T from the Trinidad and Tobago Meteorological Service

Tropical Wave 17

Tropical Wave 17 Forecast: TW17 is nearing Trinidad, Tobago and the Lesser Antilles. Scattered showers and locally heavy showers/thunderstorms forecast to begin after midnight tonight, lingering through the first half of Tuesday. Gusty winds, street flooding, landslides/mudslides, and downed trees all possible through Tuesday, particularly across NE Trinidad and Tobago. Credit:

The axis of this wave extends along 54W/55W from 15N southward. Widely scattered moderate to isolated strong rain showers are from 07N to 12N between 48W and 60W.

This wave is embedded within the ITCZ, bringing the feature across Trinidad and Tobago presently. In addition, a deep plume of tropical moisture is over T&T, fuelling showers and isolated thunderstorms mainly North of T&T at this time. Favorable upper-level conditions will support moderate to locally strong convection (thunderstorms), particularly overnight into the first half of Tuesday.

Through the early afternoon on Tuesday, Trinidad and Tobago will continue to see cloudiness, showers, and thunderstorms. Much of the heaviest activity is forecast to occur between 2:00 AM and 10:00 AM on Tuesday, with moderate to rough seas, flooding (street and flash flooding), gusty winds and landslides. Note that this wave will be similar to prior inclement weather events for the year as a result of the passage of a tropical wave.

An adverse weather advisory (either an alert/watch/warning) has not been issued for Trinidad and Tobago from the Trinidad and Tobago Meteorological Service at this time.

Tropical Wave 17 Forecast – What to Expect

Cloudiness, showers and isolated thunderstorms across the Windwards associated with Tropical Wave 17.
Cloudiness, showers and isolated thunderstorms across the Windwards associated with Tropical Wave 17.

Note: Street/Flash flooding, frequent lightning, gusty winds, landslides/mudslides are all possible beginning after midnight through the first half of Tuesday. In addition, locally severe thunderstorms may produce isolated areas, up to 50 millimeters of rainfall, across eastern parts of Trinidad and Tobago.

First Half of Tuesday (12:00 AM Tuesday through 12:00 PM Tuesday): Intermittent and scattered, to widespread showers and thunderstorms are likely through the first half of Tuesday. Activity will be similar to previous tropical waves where heavier showers and thunderstorms are isolated and locally heavy rainfall is forecast mainly across Eastern Trinidad. Heavier showers and thunderstorms are likely to remain offshore both islands, moving generally west-northwest. This means folks across Western and Southwestern Trinidad may not see significant rainfall.

Second Half of Tuesday (12:00 PM Tuesday through 12:00 AM Wednesday): A few isolated showers and thunderstorms are likely through the early afternoon, favoring Trinidad, becoming more settled as the day progresses. A mild surge of Saharan Dust is likely to begin moving across T&T by the late evening into the night.

Showers and thunderstorms are forecast to become more sparse throughout the day on Tuesday, with severe thunderstorms south of Trinidad, along Coastal Venezuela. Upper-level clouds may produce a partly to mostly cloudy day across Trinidad and Tobago.

Possible Impacts to Trinidad and Tobago

Locally Heavy Rainfall & Flooding: Based on the 12Z and 18Z Monday model runs, from Monday (8:00 PM) through Wednesday (2:00 AM), generally, over the 30 hour period, models are in agreement of less than 20 millimeters across Western half of Trinidad and between 20-40 millimeters across the Eastern half of Trinidad as well as all of Tobago. Isolated rainfall totals up to 60 millimeters are possible across Northeastern Trinidad, as well as parts of Tobago.

Isolated heavy showers and thunderstorms on Monday generally accumulated less than 10 millimeters across both islands, with isolated areas receiving up to 20 millimeters.

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 forecast to occur mainly after midnight, 12:00 AM Tuesday.

Gusty Winds: Gusty winds, generally up to 60 KM/H are likely, particularly across Northeastern Trinidad and Tobago. Gusty winds are most likely prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 60 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: 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.

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