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La Niña looming

The El Niño weather phenomenon is continuously weakening and the possibility of a developing La Niña during the second half of 2016 is now increasing, the State weather bureau said yesterday.

The Philippine Atmospheric, Geophysical, and Astronomical Services Administration said majority of climate models suggest that El Niño is in its decaying stage, returning to neutral condition, which is neither El Niño nor La Niña by mid-2016. Meanwhile, it noted the possibility of a developing La Niña during the second half of 2016.

A La Niña event is characterized by a persistent cooler than average sea surface temperature anomalies, which is below -0.5 degrees Celsius over the tropical Pacific Ocean.

Rainfall assessment last month showed that most parts of the country received way below to below normal rainfall except for the provinces of Compostela Valley, Agusan del Sur, North Cotabato, Pangasinan, Cavite, Rizal, and Metro Manila where above normal to near normal rainfall were observed.

Further analysis showed that 23 provinces were affected by dry spell while 28 provinces, mostly from Mindanao, experienced drought conditions in April.

This month, PAGASA said, marks the weakening of the easterlies and gradual start of southwest wind flow, manifested by afternoon or early evening thunderstorm activities.

Other weather systems that are likely to affect the country this month are the intertropical convergence zone or ITCZ, easterlies, low pressure areas, ridge of high pressure areas, and zero or one tropical cyclone that may enter the country’s area of responsibility.

Below to way below normal rainfall conditions are expected over Luzon and Visayas while significant portions of Mindanao are predicted to have near normal to above normal rainfall conditions.

However, drought and dry spell outlook for May show that 37 provinces will likely experience drought and 23 provinces may experience dry spell.

Drought is defined as three consecutive months of way below normal (60 percent reduction from average) or five consecutive months of below normal (21 to 60 percent reduction from average) rainfall condition. (Ellalyn B. de Vera)