In Trinidad and Tobago, waterspouts are infrequent, but they do occur, generally off the west coasts of both islands and on November 9th, 2019, that was no exception.
After an initially hot and sunny morning across Trinidad and Tobago, following the passage of a tropical wave, heavy showers and thunderstorms developed across both islands.
These showers and thunderstorms dumped heavy rainfall across parts of Western Trinidad and Tobago, with several reports of street flooding across parts of San Fernando, Freeport, Westmoorings and Carenage.
However, the thunderstorm that caught everyone’s attention was one that formed out to sea, off the coast of Store Bay and Crown Point Tobago. This thunderstorm produced a brief waterspout, lasting no longer than 2 minutes as it spun out at sea.
A waterspout is a column of cloud-filled wind rotating over a body of water.
Despite its name, a waterspout is not filled with water from the ocean or lake. A waterspout descends from a cumulus cloud. It does not “spout” from the water. The water inside a waterspout is formed by condensation in the cloud.
How Do Waterspouts Form?
There are two types of waterspouts, fair-weather waterspouts and tornadic waterspouts, which get their start as true tornadoes. Influenced by winds associated with severe thunderstorms, air rises and rotates on a vertical axis. Tornadic waterspouts are the most powerful and destructive type of waterspout only if it moves near mariners or onshore. This waterspout was a “fair-weather” waterspout.
Fair-weather waterspouts, occurring in coastal waters and are associated with dark, flat-bottomed, developing convective cumulus towers, like today’s waterspout. Waterspouts of this type rapidly develop and dissipate, having life cycles shorter than 20 minutes. They usually rate no higher than EF0 on the Enhanced Fujita scale, generally exhibiting winds of less than 108 KM/H.
Both tornadic and fair-weather waterspouts require high levels of humidity and a relatively warm water temperature compared to the overlying air. Waterspouts are most common in tropical waters like the Caribbean and the Florida Keys, and in subtropical waters, such as the islands of Greece, and off the east coast of Australia.
There are five stages of waterspout formation:
- Dark spot. The surface of the water takes on a dark appearance where the vortex, or column of rotating wind, reaches it.
- Spiral pattern. Light and dark bands spiral out from the dark spot.
- Spray ring. A swirling ring of sea spray called a cascade forms around the dark spot. It appears to have an eye at the center, similar to that seen in a hurricane.
- Mature vortex. The waterspout is now at its most intense stage, visible from the surface of the water to the clouds overhead. It appears to have a hollow funnel and may be surrounded by vapor.
- Decay. When the flow of warm air into the vortex weakens, the waterspout collapses.
The average spout is around 50 meters (165 feet) in diameter, with wind speeds of 80 kilometers per hour (50 miles per hour), corresponding to the weakest types of tornadoes on land. The largest waterspouts can have diameters of 100 meters (330 feet) and last for up to one hour, though the average lifetime is just 5 to 10 minutes.
How did the 2019 Tobago Waterspout Form?
A tropical wave moved across the region early Saturday 9th November 2019.
Warm waters allowed for rapidly rising air (updraft) to form and feed into a cumulonimbus cloud (thunderstorm).
Ample directional wind shear (winds changing direction with height), following the passage of the tropical wave, allowed that updraft to rotate and caused the waterspout to develop just offshore southwestern Tobago.
Who were impacted?
Thankfully, this waterspout remained out to sea, as the thunderstorm it was attached to moved west-southwest towards Northeastern Trinidad, but the threat of waterspouts greatly diminished.
How Frequently Does T&T Experience Waterspouts?
This is a difficult question to answer, as there really has been no good (or at least public) record-keeping of tornado or waterspout events across Trinidad and Tobago but the 2019 Tobago Waterspout is just one of many we’ve noticed in the last few years, likely due to an increase in persons with cameras near the coast.
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 and Waterspouts across Trinidad and Tobago remain a very uncommon 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.