Drought conditions are currently experienced throughout Tonga.
Drought warnings are now in force for all of Tonga.
Drier than normal conditions is expected over the next 6 months for Tonga.
El Nino Advice
Its confirmed. El Niño has arrived.
At this stage, it is too early to determine the strength of this El Niño event, but some significant impacts are expected regardless of the strength.
El Niño thresholds have been exceeded in the latest monthly and weekly tropical Pacific oceanic and atmospheric data. Sea surface temperatures are now at least 0.8 °C above normal; the western Pacific trade winds have been persistently weak; and most climate models suggest the tropical Pacific Ocean will continue to warm in coming months, remaining above El Niño levels.
Now that El Niño thresholds have been reached, forecasters are confident that the stage is set for it to continue, and possibly intensify in 2015.
In 2014, tropical Pacific Ocean temperatures briefly reached El Niño levels, but only weakly coupled with the atmosphere, and hence the warmth in the Pacific Ocean dissipated quickly in early 2015.
What is El Niño?
El Niño is the movement of warm ocean water from the north of Australia to South American crossing the Pacific Islands every 3 to 7 years. The movement of this warm water changes the weather patterns in many countries. El Nino usually lasts for 1 year.
Effects of El Niño on Tonga’s Climate and Activities
For Tonga, El Niño usually brings cooler night time temperatures from May to October, less rainfall from November to April and more cyclones than usual. El Nino years are excellent for growing sweet potatoes (provided enough water is given) and crops that depend on cooler night time temperatures but no good for rain dependant crops in the Summer time. Fruit trees and Vanilla also tend to do well during El Nino due to stress induced flowering. Tuna fisheries tend to be poor during this time due to tuna stocks migration away from Tonga waters.
Niuafo’ou recorded the highest maximum day time temperature of 33.0oC on the 3rd of April.
Rainfall received across the country during April was very low in Tongatapu. Fua'amotu recorded 17.1mm which is the lowest April rainfall in its record of 36 years. Nuku'alofa recorded 28.9mm which is the 3rd lowest April rainfall in its record of 71 years. (Refer Table 1).
Fua’amotu is currently experiencing a drought that is ranked the 3rd most severe amongst all those recorded and Nuku’alofa is ranked 10th most severe amongst all those recorded.
In the last 4 months Tongatapu and Niuatoputapu have been in drought. All island groups are now in a drought warning stage. Rainfall forecast for over the next 6 months is for drier than normal conditions throughout Tonga.
The next El Niño Advisory will be issued around mid-June 2015.
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