12:00 PM Friday 28th June 2019 Update
A recent ASCAT Scatterometer pass at 12:06 PM detected surface winds of 64 KM/H associated with the axis of Tropical Wave 13, with scattered showers and thunderstorms.
A brief lull in rainfall is occurring across Trinidad and Tobago presently, with another round of showers likely over the next 1-2 hours.
The expected gusty winds are forecast to move across Trinidad and Tobago by 5:00 PM, through the remainder of Friday. Secure loose outdoor items!
Wind gusts of 50-70 KM/H possible across both islands, up to 75 KM/H across Eastern Tobago and higher elevations of the Northern Range!
The Adverse Weather Alert
As expected, the Trinidad and Tobago Meteorological Service has issued an Adverse Weather Alert as Tropical Wave 13 nears Trinidad and Tobago. Heavy showers and thunderstorms are likely to begin after 11:00 AM on Friday, with intermittent showers and thunderstorms, occur through 5:00 PM Friday evening. Note that due to favorable atmospheric conditions, locally severe thunderstorms are possible, producing heavy rainfall and gusty winds. This event is likely to be our second heavy rainfall event for 2019
Trinidad and Tobago is NOT under any tropical storm threat, watch or warning.
Based on the latest model guidance, these scattered to widespread showers, with scattered heavy showers and thunderstorms may produce severe weather across Trinidad and Tobago. Street flooding and flash flooding are 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.
What to Expect Over Next 24 Hours
Forecast For Trinidad and Tobago
Friday, through midnight (12:00 AM Friday to 12:00 AM Saturday) – Across Trinidad, after a mostly sunny morning, increasing cloudiness with scattered to widespread showers and thunderstorms are likely. The strongest thunderstorms and heaviest showers are likely by 10:00 AM through 5:00 PM, with lingering activity through midnight. Gusty winds are the main threat, with gusts up to 70 KM/H. Across Tobago, heavy showers and thunderstorms are likely to persist through the day, with locally heavy rainfall and gusty winds up to 75 KM/H
Saturday, after midnight through 8:00 AM (12:00 AM Saturday to 8:00 AM Saturday) Initially isolated to scattered showers and the isolated thunderstorm overnight through dawn will give way to a partly cloudy morning. Much of the possible inclement weather is forecast to subside by 8:00 AM.
The Remainder of Saturday, until midnight (12:00 AM Saturday to 12:00 AM Sunday) – An increase in low-level winds, as well as Saharan Dust, is forecast as the day progresses, with degrading air quality. The upper-level trough is forecast to generate some mid to upper-level clouds across the region, resulting in a partly to mostly cloudy but hazy day.
Possible Impacts to Trinidad and Tobago
Locally Heavy Rainfall & Flooding: Based on the 00Z Friday model runs, from Friday morning (2:00 AM) through Saturday morning (2:00 AM), generally less than 20 millimeters across Tobago, with locally heavier amounts along the Southern coast of the island or where thunderstorms/heavy showers occur.
Across Trinidad, heavy rainfall is likely across Eastern parts of the island, with rainfall totals generally between 20-40 millimeters, and isolated areas receiving up to 60 millimeters, as of the latest model guidance. Across Southern and Central Trinidad, generally, 20-40 millimeters of rainfall is also forecast. Western and Northwestern Trinidad may see the “lowest” totals, as expected with weaker tropical waves in June, with generally less than 20 millimeters of rainfall forecast over the 24 hour period, though isolated heavier totals are possible in the vicinity of thunderstorms or heavy showers.
The heaviest activity is forecast to occur on Friday. 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 during the late morning through the late afternoon and again during the early hours of Saturday, across T&T. As of 9:15 AM Friday morning, over 4,000 lightning strikes have been detected across Trinidad, Tobago and coastal adjacent waters, with over 1,800 of these being dangerous cloud-to-ground lightning.
Gusty Winds: Gusty winds, generally between 50-60 KM/H are likely. Gusts up to 75 KM/H are possible across Eastern Tobago and higher elevations across the Northern Range, Trinidad, while peak gusts across the majority of Trinidad and Tobago of up to 70 KM/H may occur. Gusty winds are most likely during the latter half of Friday. These wind gusts will generally occur prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 74 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, 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.
What’s Causing This Inclement Weather?
Tropical Wave 13 is forecast to move across T&T over the next 14 hours bringing widespread showers, scattered thunderstorms and the ITCZ across the region. A deep surge in tropical moisture associated with this wave is moving across T&T presently and is forecast to persist over the next 24 hours. In addition, an upper-level trough is favorably positioned west of the region. This is creating favorable upper-level conditions for the development of heavy showers and thunderstorms across the Southern Windwards, hence the adverse weather alert.
These favorable conditions are forecast to remain in place throughout the next 24 hours, with upper level divergent and low-level convergence aiding in the development of showers and thunderstorms with the passage of the wave axis. The Intertropical Convergence Zone, or the ITCZ, is also shifting across T&T as a result of this tropical wave.