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Waterspouts

A waterspout is a column of wind that can become cloud-filled, rotating over a body of water. Waterspouts are not unheard of in Trinidad and Tobago, with several sightings reported and documented over the last few years.

These rotating columns of air over water can become damaging and life-threatening if they near boats at sea, in harbors, or even move on land, becoming a tornado.

The Origin of Funnel Clouds, Tornadoes, and Waterspouts

There is an updraft within showers and thundershowers (all convective showers), where warm air rises.

Structure of a thunderstorm. (Credit: Encyclopedia Britannica, Inc.)
Structure of a thunderstorm. (Credit: Encyclopedia Britannica, Inc.)

However, when there is a change of wind speed or direction as the air rises (wind shear), this updraft begins to rotate. This rotating updraft is called a mesocyclone. As this mesocyclone, or rotating air, moves closer to the earth’s surface, this may cause a funnel cloud to form.

A tornado is formed if this rotating updraft touches the earth’s surface (land). Alternatively, if the updraft touches the ocean’s surface or a waterbody, it is considered a waterspout.

A diagram showing how an updraft of a thunderstorm can become a rotating updraft. (Credit: Wikipedia)

A diagram shows how a thunderstorm’s updraft can become a rotating updraft. (Credit: Wikipedia)

Waterspout Formation

Waterspouts can form when winds blowing in two different directions run into each other. Along the line where the two winds meet (called a “convergence line” or “shear line”), there is a lot of rotating air near the surface.

The collision of the two winds makes air move upwards because it has nowhere else to go. This rising air carries water vapor high into the sky, creating showers and cumulus clouds.

As the air rises, it can tilt some horizontal spinning air near the surface into the vertical direction. When this vertical spin concentrates at a particular point, it starts sucking up water — and you have a waterspout.

Because waterspouts form on the line where two winds meet, you sometimes see a line of waterspouts in a row where the spinning low-level air is sucked upwards at a few different points.

Despite its name, a waterspout is not filled with water from the ocean or lake. The water inside a waterspout is formed by condensation in the cloud.

There are two types of waterspouts, fair-weather waterspouts and tornadic waterspouts, which start as true tornadoes.

Fair Weather Waterspouts

Fair-weather waterspouts occur in coastal waters and are associated with dark, flat-bottomed, developing convective cumulus towers. Waterspouts of this type rapidly develop and dissipate, having life cycles shorter than 20 minutes. They usually rate no higher than EF-0 on the Enhanced Fujita scale, generally producing winds of less than 108 KM/H.

This type of waterspout generally develops from the water’s surface and works its way upward to the cumulus or cumuliform cloud. These are more common near T&T, so you may not necessarily see a funnel extending from a cloud when one is present, but you certainly will see a swirling vortex of water droplets near the ocean’s surface, pond, or dam. However, by the time a funnel is visible, a fair-weather waterspout is near maturity. Fair weather waterspouts form in light wind conditions, so they usually move very little.

There are five stages of waterspout formation:

  1. Dark spot. The surface of the water takes on a dark appearance where the vortex, or column of rotating wind, reaches it.
  2. Spiral pattern. Light and dark bands spiral out from the dark spot.
  3. 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.
  4. 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.
  5. 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 KM/H (50 MPH) 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.

Tornadic Waterspouts

Tornadic waterspouts are tornadoes that form over water or move from land to water. These types of waterspouts form downward in a thunderstorm (cumulonimbus cloud). They have the same characteristics as a land tornado. They are associated with severe thunderstorms and may be accompanied by high winds and seas, hail, and frequent, dangerous lightning. A tornado that travels from land to a body of water would also be considered a tornadic waterspout.

Given tornadoes are already a rare phenomenon in T&T, a tornadic waterspout is very uncommon for our twin-island republic.

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.

Forecasting and Detection

We tend to look for light to near calm conditions in the forecasting phase, particularly along Western Trinidad, where triggering mechanisms for shower and thunderstorm development are dominated by sea breeze convergence and daytime heating. However, waterspouts can occur at any coast of T&T.

Looking at different heights in the atmosphere, we also look to see if there is a vertically stacked low-pressure, with a noted, decreasing temperature change and a clockwise turning of winds as you increase in height in the atmosphere.

However all these conditions can occur, but it does not guarantee waterspout formation. This is where detection comes in, as these waterspout events tend to be brief.

We lack the advanced Dual-polarimetric Doppler Radar in Trinidad and Tobago to show how winds move near and inside showers. This helps understand what kinds of hazards the thunderstorm might have (tornado, microburst, gust fronts, etc.). It also helps us understand how the thunderstorm is “feeding” itself with warm, moist air.

However, even if we had an advanced Doppler Radar, there would be difficulty recognizing the small low-level circulations associated with waterspout events on Doppler radar unless they are related to strong rotation within a tornadic supercell (which is quite rare in T&T).

This difficulty in forecasting such events results in short, if any, warning times for the public.

Occurrence and Frequency

Waterspout sightings across T&T since 2020, as documented by the International Centre for Waterspout Research
Waterspout sightings across T&T since 2020, as documented by the International Centre for Waterspout Research

In recent years, there have been more sightings of waterspouts across Trinidad (mainly) and Tobago – but this can largely be attributed to an increase in cameras across the country rather than an increase in frequency.

Based on the limited data within the last five years (2017-2022), waterspout activity is generally observed during the wet season, particularly from August through November.

Here are reported waterspout sightings across Trinidad and Tobago from late 2017 to 2021:

Waterspout Safety

Before a Waterspout

  • Listen to the radio or TV newscasts for local news and threats.
  • Keep a distress radio beacon, preferably one that is auto-activated in the water, on board your boat, or in your car in case of emergencies.
  • Know the warning signs for waterspouts.

During or if a Waterspout is sighted

  • If you see a waterspout, never attempt to navigate toward it or through it. Instead, move at a 90-degree angle away from where the swirling motion appears to be happening.
  • A waterspout can last up to an hour but typically is over within 10 to 20 minutes, so waiting it out from a distance is safe.
  • If you’re in a boat and a waterspout appears to be headed directly for you, take down any sails, close hatches, and, if possible, get below deck. Diving overboard may keep you from flying debris, but it may also put you at risk of other factors, like hypothermia.
  • If the waterspout comes ashore, it can turn into a tornado.

After a Waterspout

  • If your boat capsizes, a representative from the U.S. Coast Guard recommends, above all else, staying with your boat. If you can climb on top of the hull to reduce the time spent in potentially cold waters.
  • A mayday call can be placed on your radio, through your emergency beacon should help search-and-rescue locate your boat.

Generally, waterspouts dissipate without much impact to those on the ground. If you spot one and in a safe place, feel free to submit a report to us on our social media platforms or via email!