Adverse Weather Alert Extended Yet Again Until 5 PM Today. Dense Saharan Dust Forecast on Thursday

Update on the Adverse Weather Alert

The Trinidad and Tobago Meteorological Service has extended the Adverse Weather Alert until 5:00 PM as Tropical Wave 09 finally moves across Trinidad and Tobago. Based on analysis as of 1:30 PM Wednesday, the axis of this wave is over Tobago, between 59W and 61W. Presently, we have some thunderstorms moving across Southern and Central Trinidad, with another cluster of thunderstorms east of Trinidad. As we’ve forecast, this event has shaped up to be our first heavy rainfall event for 2019. Saharan Dust is forecast to move across Trinidad and Tobago later on Thursday, quelling this adverse weather finally.

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

Based on the latest model guidance, scattered to widespread showers, with scattered heavy showers and thunderstorms may produce severe weather across Trinidad and Tobago, until 5:00 PM. Street floodingflash flooding may still be possible. 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.

Because of the impending and ongoing adverse weather, the Trinidad and Tobago Meteorological Service has extended yet again, but likely the final time, the Adverse Weather Alert at 12:00 PM Wednesday 19th June 2019, valid through 5:00 PM Wednesday according to the Trinidad and Tobago Meteorological Service.

Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for June 19th, 2019.

Periods of rain and/or showers and isolated thunderstorms are likely to continue to affect Trinidad and Tobago, however, most of the activity is expected over Tobago. As a result of recent rainfall activity, areas susceptible to landslips/landslides are at greater risk and the presence of strong low-level winds can result in gusts in excess of 55km/hr at times. Also note that the possibility for street or flash flooding still exists during periods of 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 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 8th tropical wave has moved across Trinidad and Tobago, while the 9th tropical wave of the 2019 Atlantic Hurricane Season is forecast to move across Trinidad and Tobago this afternoon

Image Credit: Trinidad and Tobago Meteorological Service

What to Expect Over Next 24 Hours

Mostly overcast conditions are likely to persist across Trinidad and Tobago through the late afternoon, with scattered showers and thunderstorms persisting, mainly over Trinidad.

By the late evening, cloudy to mostly cloudy skies are forecast, with increasing concentrations of Saharan Dust particularly after midnight.

On Thursday, lingering moisture will be present across Trinidad and Tobago. The ITCZ is shifting to the south. Although Saharan Dust is forecast to rapidly increase as Thursday progresses, there is still the chance of an isolated heavy shower or thunderstorm, favoring Eastern parts of Trinidad. Isolated showers may also develop, mainly during the first half of Thursday, favoring Trinidad.

On Wednesday into Thursday (2:00 PM Wednesday – 2:00 PM Thursday), 24-hour rainfall accumulation is forecast to be less than 10 millimeters across Trinidad and Tobago, with isolated areas receiving between 15-40 millimeters, particularly Eastern and Central Trinidad, in the vicinity of thunderstorms.

On Thursday into Friday (2:00 PM Thursday – 2:00 PM Friday), 24-hour rainfall accumulation is forecast to be less than 5 millimeters across Trinidad and Tobago.

In addition, this tropical wave is forecast to bring a trade wind surge, with wind gusts beginning on Wednesday much of the Eastern Caribbean of 60-70 KM/H, and at times, higher. Parts of the Southern Windwards are already seeing sustained winds of 50 KM/H and gusts to 70 KM/H.

Seas are generally forecast to remain moderate and occasionally rough through the next 24 hours, with waves up to 2.5 meters in open waters, occasionally up to 3.0 meters, particularly east of Tobago. Over the next 3 days, seas are likely to remain moderate with waves up to 2.5 meters in open waters. In sheltered areas, seas are below 1.0 meters. Note that in the vicinity of heavy showers or thunderstorms, seas may be locally rough and/or choppy, both in open waters and sheltered areas.

Temperatures across both islands are forecast to remain generally cool, with maximum high temperatures between 28°C across both islands due to showers and cloud cover.

Possible Impacts to Trinidad and Tobago

Flooding: 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. Rainfall accumulations between 20-50 millimeters, with isolated areas between 50-100 millimeters were recorded across both Trinidad and Tobago over the last 48 hours. While most of this rainfall is generally welcome, some rivers across Northeastern Trinidad are at elevated levels. As of 2:00 PM Wednesday, reports of street flooding have already been coming in across parts of Freeport and Claxton Bay as a thunderstorm moves across the Southern half of Trinidad.

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

Gusty Winds: Gusty winds, generally between 50-60 KM/H are also possible. By late Wednesday, these maximum wind gusts may increase to 60-70 KM/H, particularly across Northern Trinidad and Tobago. These wind gusts will generally occur 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, with weaker trees coming down and there may be some inconvenience when walking against the wind gusts. Light outdoor objects may topple or become airborne such as garbage cans, loose galvanize or construction material and other outdoor furniture. Tents may jump.

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. As a result of recent rainfall activity, areas susceptible to landslips/landslides are at greater risk.

Dense Saharan Dust Inbound

Saharan Dust Overview For Wednesday 19th June 2019
Saharan Dust Overview For Wednesday 19th June 2019

Saharan Dust concentrations across Trinidad and Tobago are minimal but only for the next 24 hours. Across much of the Eastern Caribbean, a dense plume of Saharan Dust has been moving across the islands keeping air quality levels at moderate for nearly all islands, occasionally becoming unhealthy for sensitive groups. As of 2:00 PM Wednesday 19th June 2019, islands across the Eastern Caribbean are experiencing moderate air quality with the exception of Barbados, which is experiencing air quality levels of unhealthy for sensitive groups. Persons with respiratory ailments, heart disease, the elderly and children need to take the necessary precautions!

5-Day Air Quality Index, Saharan Dust Forecast For Trinidad and Tobago. A dense plume of Saharan Dust is forecast to make its way across Trinidad and Tobago on Thursday night, lingering through Saturday. On Saturday into Sunday, Tropical Wave 10 is forecast to move across Trinidad and Tobago, as well as the ITCZ, bringing some relief.
5-Day Air Quality Index, Saharan Dust Forecast For Trinidad and Tobago. A dense plume of Saharan Dust is forecast to make its way across Trinidad and Tobago on Thursday night, lingering through Saturday. On Saturday into Sunday, Tropical Wave 10 is forecast to move across Trinidad and Tobago, as well as the ITCZ, bringing some relief.

Across Trinidad and Tobago, the passage of two tropical waves as well as the presence of the ITCZ has shielded the islands from Saharan Dust. Our neighbors to the north, however, have been suffering from degraded air quality for the last week. Saharan dust is forecast to rapidly increase on Thursday. By Thursday night, peak concentrations are likely across Trinidad and Tobago, with air quality being reduced to unhealthy for sensitive groups.

At moderate air quality levels, unusually sensitive groups should consider reducing prolonged or heavy exertion.

At air quality levels that are unhealthy for sensitive groups, there is the increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease & the elderly. People with respiratory or heart disease, the elderly and children should limit prolonged exertion.

By Saturday into Sunday, air quality is forecast to return to good levels as the ITCZ and tropical wave 10 moves across the region. More on this later tonight in the tropical update.

 00Z June 19th 2019 NASA GEOS-5 Dust Model showing several surges of Saharan Dust moving across Trinidad, Tobago and the Eastern Caribbean over the next 10 days. Credit: Weatherbell
00Z June 19th 2019 NASA GEOS-5 Dust Model showing several surges of Saharan Dust moving across Trinidad, Tobago and the Eastern Caribbean over the next 10 days. Credit: Weatherbell

Sensitive groups such as persons with respiratory ailments, children, the elderly and cardiopulmonary disease should take the necessary precautions on days where dust concentrations degrade air quality to moderate to unhealthy for sensitive groups.

Saharan Dust Precautions
Saharan Dust Precautions

What’s Causing This Inclement Weather?

A tropical wave (09) is moving across Trinidad and Tobago presently. A deep surge in tropical moisture associated with this wave is moving across T&T presently and is forecast to persist over the next few hours. In addition, the ITCZ is present across T&T, generating favorable low-level convergence and aided by favorable upper-level divergence.

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.

These favorable conditions are forecast to remain in place throughout the day, with upper level divergent and low-level convergence aiding in the development of showers and thunderstorms with the passage of the wave axis.

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