Overview

Recent observations and analyses of oceanic and atmospheric indicators suggest that the climate system is  evolving towards a re-emergence of  La Niña conditions. A cooling trend of sea surface temperature over the central eastern equatorial pacific ocean has been noted since August 2011.  Dynamical and  statistical computer models suggest a cold event considered to be weak compared to last year’s  La Niña,  where it started on the 3rd quarter of year 2010 and  ended in May 2011.

Based on the above developments near to above normal rainfall conditions are expected to impact the Philippine climate  on the last remaining months of 2011.  Occasional extremes of rainfall particularly over the eastern section of the Philippines is likely to occur as rain- causing weather systems are expected to enhance convection associated with  a La Niña.

November to December 2011

The last two months of the year follows a notable decrease of seasonal rainfall as we approach the beginning of the dry season in the early months of the following year. The month of November marks the early northeast  monsoon winds which begin to strengthen and significantly contribute to seasonal rain over the eastern side of the Philippines. On the month of December, occasional drop of temperature particularly during night time signals the manifestation of a changing season. The combined effects of both the cold front propagating towards the  east, the northeast monsoon wind flow, and the enhanced easterly winds may characterize the causes of heavy rainfall in the eastern side.

The weather systems likely to influence the country are the tail end of the cold front, ITCZ,  ridge of high pressure area, easterlies and one (1) to two (2) tropical cyclones. Tracks of tropical cyclone during this period are likely across central and southern parts of Luzon, and Visayas with secondary tracks over Northern Mindanao.

Rainfall distribution during November is likely to be above normal  in extreme northern  Luzon, most parts of Nueva Ecija, Mindoro, Romblon,  Panay islands, most of Palawan, most of the northern parts of Negros and Cebu, and the western side of Bohol. The rest of the country is expected to have near normal rainfall.

For December, most of Luzon is likely to experience above normal rainfall except for some northeastern parts of Isabela and Cagayan, Camarines Sur, Albay, and a small eastern area of Quezon province.  Likewise, above normal rainfall is expected  over Palawan, Mindoro, Romblon, southern parts of Negros and tip of southern Cebu,  ARMM and SOCCSKSARGEN provinces, Lanao del Norte, Misamis Occidental, and Davao del Sur.

PAGASA will continue to monitor atmospheric and oceanic conditions affecting the country. The public is advised to take precautionary measures against the adverse impacts likely to occur.  Updates and advisories will be issued as appropriate particularly on flood, landslides and dry spell conditions if any, as the season progress.

For further information, please contact the Climatology and Agrometeorology Division (CAD) at telephone nos. 434-0955 or 434-9024.

For further information, please contact the Climatology and Agrometeorology  Division (CAD) at telephone nos.     929-1953 or 434-0955.