Recent weather phenomena in Sri Lanka

During the past few weeks, we have had many stories to talk about. The 15th SAARC Summit topped the list, while the closing of roads and transport problems also took prominence.

However, some important weather-related news also grabbed the attention of the people. Today we thought of telling you about these recent weather phenomena, to make you aware of what’s really happening around you.

Some media reported these incidents as tornado strikes. “Tornadoes rarely occur in Sri Lanka. None of the incidents that took place recently could be attributed to a tornado,” said Deputy Director, Department of Meteorology, S.R. Jayasekera.

As you all may know, two major incidents happened in Sri Lanka over the past few days; one is a waterspout and the other is a downdraft,” he added.

Waterspouts

Let us explain about the waterspout first. On July 25, around 1 p.m., those who were by the Colpetty beach had seen an unusual thing like an upright elephant trunk on the water. Many were not aware of this phenomenon. Though we didn’t know at that time what it was,meeterologists claim that it was a waterspout.

According to Jayasekera, the first waterspout witnessed in Sri Lanka was in 2005, in Negombo. Waterspouts normally develop as their parent cloud, a cloud known as cumulonimbus, is in the process of development. From the flashes of lightning we can easily identify these type of clouds. These are the clouds that create thunderstorms.

There are two main types of waterspouts, non-tornadic and tornadic. Waterspouts that are not associated with a rotating updraft of a supercell thunderstorm are known as ‘non-tornadic waterspouts’. This is the most common type of water spout in the world. These types occur mainly in the coastal waters. The one we had in Sri Lanka is a non-tornadic waterspout.

Tornadic waterspouts occur over water. These waterspouts are identical to traditional land-based tornadoes. A tornado which travel from land to a body of water would also be considered as a tornadic waterspout. These waterspouts shoot the water upward. This type is weaker than most of its land counterparts.

The speed of a waterspout is roughly around 300 km/hour. Though the lifetime of a waterspout is very short, it can do a lot of damage to boats, vessels and even ships because of its speed.

“Waterspouts occur suddenly. So, they are unpredictable. Preventing damages is not practical when it comes to a case like this,” said Jayasekara. “All that you can do is to avoid that area when you see a waterspout forming. If you can identify the cumulonimbus cloud, that will be the best sign to avoid the area,” he added.

Downdraft

The other major weather-related incident that occurred in Sri Lanka during the past few days is the downdraft that took place in Hungama and Ambalantota on July 28. The downdraft struck the area for just three minutes, but within that short period, 30 houses were damaged in Hungama and 14 in Ambalantota.

“Downdrafts come from the clouds, when the upper wind flow is very high,” explained Jayasekera. There was a lot of confusion about this incident too. People were not sure whether this was a downdraft or a tornado.

According to Jayasekera, in a tornado, you might be able to see trees fallen in every direction, since the wind flow rotates. When it’s moving; in a downdraft, the wind flows only in one direction, resulting in trees and roofs falling in one particular direction. Downdrafts are less hazardous than tornadoes,he explained.

- Janani Amarasekera