La Niña, a weather pattern that occurs in the Pacific Ocean, is round the country’s shoreline and will prevail until early 2021, the Philippine Atmospheric, Geophysical and Astronomical Services Administration announced Friday.
Pagasa administrator Dr. Vicente Malano said: “Recent oceanic and atmospheric indicators signify La Niña is present in the tropical Pacific. Since June, the sea surface temperature in the central and equatorial Pacific started to cool and further strengthened in September reaching La Niña threshold.”
“Based on the latest forecast, weak to moderate La Niña is likely to persist until the first quarter of 2021.”
Most parts of the country must brace for near to above normal rainfall conditions from October to March next year, he said.
There would be five to eight tropical cyclones to enter the Philippine area of responsibility, most of which would make landfall, he added.
He warned that these tropical cyclones might further enhance the northeast monsoon and could trigger floods, flash floods and rain-induced landslides over susceptible areas, particularly on the eastern sections of the country.
Susceptible areas mean that these would normally receive greater amounts of rainfall.
Adverse impacts are likely over the vulnerable areas and sectors of the country, Malano said.
The weather bureau said there could be a 75 percent chance for La Niña to become full blown characterized by above-normal rainfall conditions and increased tropical cyclone activity from October to March next year.
With La Nina, strong winds blow warm water at the ocean’s surface from South America to Indonesia. As the warm water moves west, cold water from the deep rises to the surface near the coast of South America.
La Nina refers to the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific. Typically, La Nina events occur every 3 to 5 years or so, but on occasion can occur over successive years. La Nina represents the cool phase of the El Nino/Southern Oscillation (ENSO) cycle.
Like El Niño, La Niña impacts include drought conditions, or worsening of, below or above average temperature and precipitation fluctuations across the United States which can all be very harmful to crop growth and/ or human health even after the La Niña event is no longer occurring in the Pacific Ocean.
El Niño and La Niña are opposite phases of a natural climate pattern across the tropical Pacific Ocean that swings back and forth every 3-7 years on average.
By modifying the jet streams, El Niño and La Niña can affect temperature and precipitation across the United States and other parts of the world, experts said.