TTMS Update: Adverse Weather Alert In Effect Now Only For Trinidad Until 12 AM Friday

The Adverse Weather Alert

The Trinidad and Tobago Meteorological Service has updated the Adverse Weather Alert (Yellow Level) as the ITCZ affects Trinidad. Occasional heavy showers and thunderstorms are likely, according to the TTMS until 12:00 AM Friday 16th August 2019.

Note that due to favorable atmospheric conditions, locally severe thunderstorms are possible, producing heavy rainfall and gusty winds, mainly across Trinidad.

Trinidad and Tobago is NOT under any tropical storm threat, watch or warning.

Based on the latest model guidance, these showers, with isolated heavy showers and thunderstorms may produce severe weather across Trinidad. Activity is forecast to decrease as the evening progresses. Regardless, street floodingflash flooding. Gusty winds are likely in the vicinity and during heavy showers or thunderstorms. These gusty winds and heavy rainfall will be capable of triggering landslides in landslide-prone areas, as well as downing trees and utility poles. See below for more details on what impacts to expect.

Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for August 15th-16th, 2019.

Occasional showers and isolated heavy showers/thunderstorms are still likely in varying localities over Trinidad. The possibility of landslides/landslips remains, mainly along hilly areas. Street and/or flash flooding and gusts up to 65km/h are likely near heavy downpours.” according to the Trinidad and Tobago Meteorological Service. This “alert” status takes into account the possibility of the event occurring. This adverse weather event is very likely.

The color of the watch indicates the severity of the event and the probability of the event occurring. Currently, the alert level is at Yellow. This means that the hazard is possible to be aware of the impacts of Street/Flash Flooding and Gusty Winds in your area. Areas prone to landslides should also be aware of the hazard and impacts.

Image Credit: Trinidad and Tobago Meteorological Service

The 35th tropical wave of the 2019 Atlantic Hurricane Season moved west of Trinidad and Tobago. The 36th tropical wave of the 2019 Atlantic Hurricane Season is approaching Trinidad and Tobago, forecast to move across the area Saturday into Sunday.

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.
Image Credit: Trinidad and Tobago Meteorological Service

What to Expect Over Next 24 Hours

The Takeaway: Showers and thunderstorms are likely to continue across (mainly) Trinidad through the evening. Conditions are forecast to become gradually settled by midnight.

A mostly settled Friday is ahead, with hazy and sunny periods. Late morning through the afternoon, isolated showers are possible across Trinidad, with the chance of a thunderstorm across Western Trinidad.

Locally heavy rainfall associated with showers and thunderstorms, gusty winds up to 65 KM/H and landslides possible.

Generally, widespread severe weather is not likely. Localized to scattered severe weather reports are possible, with landslides across the Northern Range and street/flash flooding across Southern and Eastern Trinidad possible through tonight. Street flooding possible tomorrow, Friday, across Western Trinidad.

As expected, adverse weather affected Trinidad and Tobago over the last 2 days. The Trinidad and Tobago Meteorological Service updated the Adverse Weather Alert for the third time, to now only include Trinidad, through 12:00 AM tonight.

  The ITCZ is across the region, with favorable atmospheric dynamics, triggering locally heavy rainfall with street/flash flooding, gusty winds and inclement weather across Trinidad through tonight. Credit: Weathernerds.org
The ITCZ is across the region, with favorable atmospheric dynamics, triggering locally heavy rainfall with street/flash flooding, gusty winds and inclement weather across Trinidad through tonight. Credit: Weathernerds.org

As forecast, this wave has dragged the ITCZ across T&T yet again, through the end of the week. Combined with favorable upper-level conditions and increased low-level moisture, periods of showers and thunderstorms are likely to continue through the night.

Based on the latest model guidance, isolated showers and thunderstorms are forecast to move across Trinidad, with heavier activity favoring much of Eastern Trinidad overnight. Isolated showers and thunderstorms are forecast to favor Trinidad yet again on Friday, interrupting sunny to partly cloudy skies.

Locally Heavy Rainfall & Flooding: Based on the latest model runs on Thursday evening, from Thursday afternoon (2:00 PM) through Saturday morning (2:00 AM), generally, over the 36 hour period, models are in agreement of fewer than 10-15 millimeters across of Trinidad and Tobago and between 15-30 millimeters across isolated areas of Trinidad and up to 40 millimeters across 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.

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

Gusty Winds: Gusty winds, generally between 40 and 65 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 65 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.

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