Met Office: Volatile, erratic wet season approaching

The content originally appeared on: Trinidad and Tobago Newsday

Meteorologist Ean Wallace speaks at the National Climate Outlook Forum at Trinidad and Tobago Civil Aviation Authority Training Centre on Caroni North Bank Road, Piarco on May 21. – Faith Ayoung

The TT Meteorological Service is predicting the upcoming rainy season will be volatile and erratic and, in future, the country needs to prepare for hotter days.

This was said as the Met Office hosted its sixteenth National Climate Outlook Forum at the TT Civil Aviation Centre, Caroni North Bank Road, Piarco on Tuesday.

The major focus was climate change and the effect it has on TT.

Meteorologist Ean Wallace said the upcoming rainy season would be “wetter than normal.”

Wallace explained the three major climate factors that drive the rainy season – El Nino/La Nina, sea surface temperatures east of TT and Atlantic Meridional Mode (AMM) (north/south seas surface temperature gradient.)

He said, “With above average sea surface temperatures in the Atlantic, this can be a major factor in the strength of tropical waves and the fluctuation of the Inter Tropical Convergence Zone (ITCZ).

“When we see a warmer than average tropical Atlantic relative to the southern tropical Atlantic, the opposite is also true.

“From June to September, the AMM is positive. This means we will continue to see warm conditions that we have seen over the past few months and there will be record warm conditions in the Atlantic Ocean, and when the AMM is in a positive mode, the ITCZ is displaced throughout our area more frequently and becomes more volatile.”

Wallace said the ITCZ provides TT with most of its rainfall.

On April 4, Colorado State University released its first seasonal forecast for the North Atlantic Hurricane Basin (TT and the Caribbean hurricane basin), predicting 23 main storms, 11 hurricanes and five major hurricanes.

Similar statistics have also been released by AccuWeather Co, as it predicted 20-25 storms, eight-12 hurricanes and four-seven major hurricanes.

In 2023, AccuWeather predicted 19 storms, seven hurricanes and three major hurricanes.

On Tuesday, Wallace said, “The commonality between all these forecasts is that they are all above average for tropical activities in the entire region.”

In the area of interest for TT, four storms have formed per year from 1991-2020.

This year, the Met office predicts six storms, three-eight storms likely to form in the area and three hurricanes, with one-four hurricanes likely to form.

Wallace said, “The activity we will see this year will likely be in line with that of 2023.

“This is going to be a volatile and erratic Atlantic hurricane season.”

In its presentation, the Met Office said heightened tropical storm activity is expected from August-October but will most happen in August and September.

Meteorologist and acting climatologist Kaidar Kissoon produced the presentation.

He said, “A season only needs one tropical storm or hurricane to cause devastation in TT, for it to be an active season. Citizens should increase preparation.”

However, with climate change and its effects, the Met Office said, TT will see a wetter than usual start to the rainy season.

It said, “The first half of the wet season, June-July-August, is likely to be near normal or above normal.”

Wallace warned the public to be wary during the rainy season, as rainfall exceeding 250 millimetres (mm) monthly, 25 mm per 24 hours, and five-day and three-day wet spells are all indicators of flooding.

In June, the probability of exceeding 250 mm is between 13 and 93 per cent, with Sangre Grande and its environs having the highest chance of flood events.

In August, there is a ten-82 per cent chance of rainfall exceeding 250 mm, also affecting Sangre Grande.

During this rainy season, the Met Office predicts a 52 per cent chance of an above-normal number of heavy rainfall days (above 25 mm) and a 43 per cent chance of above-normal extremely heavy rainfall days (above 50 mm).

TT will likely have between 11-22 heavy rainfall days and two-six extremely heavy rainfall days. At least five days are likely to produce 75 mm of rainfall.

With regard to three and five-day wet spells, there is a 53 per cent chance of above-normal rainfall for three consecutive days (10 mm), while there is a 73 per cent chance of having a normal number for five consecutive days of rainfall.

The Met Office said while flood risk exists nationwide, the risk is moderately higher than normal across flood-prone areas – northeast, northwest and southern TT.

Central west and southeast TT also have a slightly higher than normal flood potential.

The Met Office warned citizens, disaster preparedness, flood-alleviating agencies and emergency responders to “ramp up preparations for the rainy season.”

Increase in TT temperature

With the theme Prepared Communities Make A Resilient Nation, the Met Office acting director Shakeer Baig said, “The ultimate goal of our discussions is to enhance the resilience of TT.

“We must work towards a future where our communities are better today for the impacts of climate change, where our economic activities are sustainable and our natural resources are protected.”

During the questions and answers segment of the forum, the panel, consisting of Wallace, Baig and meteorologist Gary Benjamin, were asked if climate change has made it harder to predict the weather.

Wallace said while climate change has been the biggest problem for small-island states such as TT, the accuracy of reporting from the Met Office has only increased over the last few years.

With regard to the increase in temperatures in TT, a hot day is defined as being 34 degrees Celsius.

Baig said when the Met Office looked at data from 1961-1970 and examined how many hot days there were during that time, using the 34-degree Celsius marker, there were four hot days.

Baig said the Met Office then looked at the data for 2011-2020 and used the same criteria.

The data showed 415 hot days.

“This shows that TT, being a part of the global village, is being affected by climate change.”

Baig said data from 1946 to the present was also examined and it was discovered that TT has been warming by 0.28 degrees C for every decade since 1946.

“This is higher than the global average increase in temperature. The average maximum temperature during the night has also increased.”

Baig said he would not be surprised, based on the scientific viewpoint and observation, that in the next decade 35 degrees C being the maximum will be the norm.

“Our temperatures are increasing. We have to be prepared for hotter days. We need to implement measures if the heat is stressing us out and if you fall ill, we need to be hydrated, we need to wear light clothing and stay out of the sun on very hot days.”