In Trinidad and Tobago, we generally experience a confirmed tornado touchdown once every 10-20 years. Our last was the 2009 Caroni Plains tornado, and today seems to keep that recurrence interval accurate.
After an initially hot and sunny morning across Trinidad, daytime heating triggered the rapid development of heavy showers and thunderstorms across the Western half of the island.
These showers and thunderstorms dumped 20-50 millimeters of rainfall across much of west-central Trinidad, producing street flooding across parts of Chaguanas and environs as well as parts of Southwestern Trinidad.
Although it was initially reported as a funnel cloud, reports did eventually come in of a touchdown along at Dyette Street, Cunupia and another at Jerningham Railway Road, Cunupia, with minor roof damage reported. Once a funnel cloud touches down on land, it is designated as a tornado.
How Did the Tornado Form?
A tropical wave moved across the region on Monday 16th September 2019. Near calm to light winds were recorded across Trinidad, with near calm to calm conditions prevailing across Central Trinidad.
This light winds and increased atmospheric moisture from the ITCZ across the islands allowed daytime heating and sea breeze convergence to act as a trigger for convective activity.
Several atmospheric conditions needed to come together across Central Trinidad for this rare phenomenon to form.
Tornado formation is not completely understood and there are two main ways a tornado may form. In the case of the 2019 Cunupia tornado, the below mechanism is the likely explanation for how this tornado formed.
Firstly, a horizontal spinning effect must form on the Earth’s surface. This usually originates in sudden changes in wind direction or speed, known as wind shear. Secondly, a thundercloud, or occasionally a cumulus cloud, must be present.
During a thunderstorm, updrafts are occasionally powerful enough to lift the horizontal spinning row of air upwards, turning it into a vertical air column. This vertical air column then becomes the basic structure for the tornado. Tornadoes that form in this way are often weak and generally last less than 10 minutes.
In the case of the 2019 Cunupia Tornado, it lasted generally 7-15 minutes and minimal damage occurred.
Who were impacted?
“I was on my back porch, watching towards the east. It started off with a big with cloud shaped like a v between the dark clouds. It started to mvoe around, becoming thin and long. I began to feel scared when I saw the base of the cloud spinning.”Indra Harricharan, Eyewitness, Monday 16th September 2019.
This funnel cloud and eventual tornado were spotted from mainly Cunupia due to heavy rainfall obscuring the view from other distant locations. Based on video and radar evidence, the touchdown was brief, in the vicinity of Jerningham Junction and Cunupia.
There was damage reported along Dyette Street, Cunupia, where sheets of galvanize were ripped off a home and shed. There were also unconfirmed reports of damage occurring along Phase 1, Chin Chin, Cunapia, in the vicinity of Flirts Bar.
Based on video evidence, this funnel cloud and tornado lasted a few minutes and produced minimal damage.
Tornadoes are generally rated on a damage-based scale called the Enhanced Fujita Scale in the United States and Canada, though other regions have different tornado scales. This scale uses the damage (or lack thereof) to rate the wind speeds of the tornado after the event.
Based on details of this tornado, we would rank this as an EF-0 tornado. With an EF-0 tornado, winds between 105 KM/H to 137 KM/H occur. Damage typical for this scale of a tornado is a peeled off surface from some roofs; some damage to gutters or siding; branches broken off trees; shallow-rooted trees pushed over.
Note that confirmed tornadoes with no reported damage (i.e., those that remain in open fields) are always rated EF0.
Street & Flash Flooding Across West-Central Trinidad
Monday’s showers and thunderstorms were part of a forecast multi-day heavy rainfall event across Trinidad and Tobago due to the passage of two tropical waves with the forecast to ITCZ remain across the region with favorable atmospheric dynamics in place.
Heavy to violent rainfall rates, up to 100 millimeters per hour occurred across parts of Chaguanas, Chase Village, Charlieville, Endeavour, Montrose, Freeport, Couva and surrounding areas. Rainfall accumulations on Monday 16th September 2019 alone ranged between 20 to 50 millimeters in the affected areas.
Power outages due to frequent lightning were also rampant across Central Trinidad, with close to 20 areas reporting power interruptions.
Inclement Weather Elsewhere
There were reports of a downed tree along the North Coast Road. As the Intertropical Convergence Zone is forecast to linger across the region through the week, periods of inclement weather is forecast with street, flash and riverine flooding possible. Gusty winds, landslides, localized power outages are also possible, particularly on Tuesday into Wednesday.
This upcoming inclement weather is forecast due to back to back tropical waves, the ITCZ remaining across the region, as well as favorable atmospheric dynamics allowing daytime heating, orographic precipitation, and sea breeze convergence to affect the islands.
How Frequently Does T&T Experience Tornadoes?
This is a difficult question to answer, as there really has been no good (or at least public) record-keeping of tornado events across Trinidad and Tobago.
It’s even more difficult to ascertain what exactly was a tornado versus the more common straight-line winds across Trinidad. Media reports and the general public usually attributes major wind damage to “twister-like” or “tornado-like” events.
Nine times out of ten, wind damage across Trinidad and Tobago can be attributed to gusty winds from thunderstorms or straight-line winds.
However, we’re trying to build a database of these events, by scouring media reports dating back to the early 1900s to come up with how frequently these events occur and where have they occurred in the past.
Tornadoes across Trinidad and Tobago remain a very rare feature, but due to a lack of technology to issue and disseminate timely warnings to the public, it is imperative you know what to do in the event one occurs.