Here comes La Niña

Strong rains, flash floods, erosion, crop losses - these are just some of the problems Filipinos can expect as La Niña hits the country this summer.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) based its forecast from the increases in the incidence of typhoons, floods and frequent heavy rains since November last year.

"The persistence of present oceanic and atmospheric patterns in the next two months will confirm the occurrence of a La Niña episode and continue to influence the climate of the Philippines," weather bureau chief Graciano Yumul said.

La Niña is the counterpart of the climate phenomenon called El Niño, which was first observed and named by fishermen off the coast of South America. El Niño -- which got its "Christ child" name because of the its tendency to occur around Christmas -- describes the the appearance of unusually warm water in the Pacific Ocean. This results in a reversal of normal weather patterns -- drought during the rainy season, deluges during summer.

ow does La Niña affect the country's weather? According to PAGASA, "La Niña's effects could be manifested in above the normal rainfall conditions in major parts of the country, particularly along the eastern sections. This is mainly due to more intense northeast monsoon and tropical cyclone activities."

The coming La Niña would greatly affect the country's eastern seaboard, particularly Cagayan Valley, Isabela, Southern Leyte, Leyte, Agusan del Sur and Norte, Davao Oriental, Samar, Aurora and the Bicol provinces. These regions will see a lot of soil erosion. "When land is denuded of trees, scorched by burning, and deprived of its humus by intense heat, the earth soon erodes," explains Steve Musen, the director of the Davao-based Mindanao Baptist Rural Life Center (MBRLC) Foundation, Inc.

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El Niño phenomena

The series of storms that devastated Luzon in 2009 and the menacing persistence of El Niño have convinced state experts at the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) that the country will be faced by abnormal climate and harsher weather disturbances this year.

"It has been very difficult for us to expect a normal climate outlook for (this) year because of glaring climate variabilities and abnormal trends," Dr. Susan Espinueva, chief of PAGASA Hydrometeorological Division, said.

"We began to observe this two or three years back when we realize that these abnormal trends in climate was the impacts of climate change and variability," she noted.

The top hydrologist noted that El Niño cycle used to happen after four to seven years, instead of every other year, which began to occur since 2007.

Espinueva also expressed concern that the dry spell conditions due to El Niño in Capiz, Masbate, Northern Samar, and Occidental Mindoro since September hinted an exact opposite climate to be experienced all throughout the country come second half of 2010.

She also explained that the phenomena is followed by La Niña that dramatically increases rainfall.

"With or without El Niño, we recorded a trend wherein the accumulated amount of rainfall in a year stays the same annually. It (the figure) does not vary, which means that of we have less rainfall for the first half, we will more rainfall in the second half of 2010," she said.

"So if we have drought conditions this summer, we will have wetter rainy season," she said, adding that the country may even have strong storms and unusually erratic typhoons similar to storm "Ondoy" and typhoon "Pepeng" last year.

PAGASA Climatology and Hydrometeorology Division chief Dr. Flaviana Hilario likened the climate outlook this year to what happened in 2007 when typhoon "Marce" left several provinces in ruins in August immediately after the drought conditions were severely felt from June to July.

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Typhoons in the Philippines

Typhoons in the Philippines describes the most notable tropical cyclones to enter the Philippine Area of Responsibility and affect the Philippines. Bagyo is a term referring to any tropical cyclone in the Philippine Islands. An average of 6 to 7 tropical cyclones hit the Philippines per year. A bagyo is categorized into four types according to its wind speed by the PAGASA. All tropical cyclones, regardless of strength, are named by PAGASA. Tropical depressions have maximum sustained winds of between 55 kilometres per hour (30 kn) and 64 kilometres per hour (35 kn) near its center. Tropical storms have maximum sustained winds of 65 kilometres per hour (35 kn) and 119 kilometres per hour (64 kn). Typhoons achieve maximum sustained winds of 120 kilometres per hour (65 kn) to 185 kilometres per hour (100 kn), with super typhoons having maximum winds exceeding 185 kilometres per hour (100 kn). The most destructive tropical cyclone to impact the Philippines was Tropical Storm Thelma in 1991, which killed thousands of people from its resultant flooding. The wettest known tropical cyclone to impact the archipelago was the July 1911 cyclone which dropped over 1,168 millimetres (46.0 in) of rainfall within a 24 hour period at Baguio City. At least 30 percent of the annual rainfall in the northern Philippines could be traced to tropical cyclones, while the southern islands receive less than 10 percent of their annual rainfall from tropical cyclones.