Image courtesy Trinidad and Tobago Meteorological Service (TTMS).

Expect La Niña conditions between September and November of this year, warns the Trinidad and Tobago Meteorological Service (TTMS).

“For Trinidad and Tobago, La Niña conditions and La Niña-like patterns often lead to increased rainfall, and a wetter than usual local wet season,” the TTMS says in an advisory issued today.

It adds: “It also tends to influence increased tropical cyclone activity in the North Atlantic Ocean, but there is no guarantee that these will occur.”

Image courtesy Trinidad and Tobago Meteorological Service (TTMS).

Forecasters at the TTMS explain that the El Niño-Southern Oscillation (ENSO) is currently neutral but the outlook remains at La Niña Watch. This means the chance of La Niña forming in the next couple of months is 50% or greater.

According to the TTMS, continued cooling of the sea surface temperatures (SSTs) in the eastern/central tropical Pacific Ocean during the past four (4) weeks resulted in increasing cooler than average SSTs. This was accompanied by related changes in the overlying atmospheric weather patterns in the form of stronger than average trade winds.

“Together, these changes suggest that conditions in the tropical Pacific Ocean have transitioned further towards La Niña formation,” the TTMS notes. “Most of the international models and the consensus forecast favour additional cooling over the next three months, with thirteen of the eighteen dynamical models favouring La Niña thresholds during September and October.”

Image courtesy Trinidad and Tobago Meteorological Service (TTMS).

A Guide to El Niño/La Niña

An El Niño (La Niña) is declared when the average SSTs in the central and eastern equatorial Pacific Ocean become at least 0.5oC warmer than average (-0.5oC cooler than average) in the preceding month and the warming (cooling) is expected to persist for five consecutive overlapping three-month periods. This must occur together with a corresponding change in the overlying atmospheric circulation.

The TTMS El Niño/La Niña Watch is activated when the ENSO Outlook indicates a probability of approximately 50% chance or greater for development of El Niño or La Niña.