SEASONAL CLIMATE OUTLOOK
JULY - DECEMBER 2018
El Niño Southern Oscillation (ENSO)-neutral conditions are present in the tropical Pacific and likely to continue until July-August-September season. However, warmer than average sea surface temperatures (SSTs) have persisted with majority of climate models predicting an increasing chance (~ 65%) of El Niño to develop during the September-October-November season and will likely continue until the Dec-Jan-Feb 2018-2019 season. With these current state and outlook, El Niño Watch is activated.
July to September 2018
Warm ENSO-neutral condition is likely to prevail during the season.
The normal climate pattern during these months are characterized by widespread and heavy rainfall affecting the western sections of Luzon and Visayas since this is the peak of the Southwest (SW) monsoon season or “Habagat”. Likewise, tropical cyclones are more active during this period with average tracks mostly located over the northern part of the country which could enhance the SW monsoon. Rain-causing weather systems such as thunderstorms, inter-tropical convergence zone (ITCZ), low pressure areas (LPAs), SW monsoon and six (6) to eight (8) tropical cyclones will dominate the season. However, breaks in the monsoon events are also expected to occur as the ridge of the North Pacific high pressure area (HPA) extends towards the country, giving warm and sunny weather in some affected areas.
Rainfall forecast for the season is likely to be near normal in most parts of Luzon and Visayas. However, most parts of Mindanao are expected to experience below normal rainfall conditions with some areas in the central part of the region that will likely receive near normal rainfall. In general, surface air temperatures are expected to be near to slightly warmer than average in most parts of the country during the season.
Gradual recession of rains associated with the SW monsoon is expected during the later part of September and the start of the transition period from the SW monsoon to the Northeast (NE) monsoon season is expected.
October to December 2018
Transition from ENSO-neutral to El Niño is likely during the period.
The period covers the first half of the NE monsoon season. The weather systems likely to influence the country are the easterlies, ITCZ, easterly wave, LPA, ridge of HPA, tail end of the cold front, NE monsoon and four (4) to six (6) tropical cyclone occurrences. Tropical cyclones originating from the northwestern Pacific Ocean tend to move in a westerly direction, with average tracks across central and southern Luzon and secondary tracks over Visayas and Northern Mindanao.
For October-November-December season, generally below normal rainfall conditions are expected over most parts of Luzon, including Mindoro provinces, Palawan and Iloilo province. On the other hand, the eastern section of Luzon, most parts of Visayas and Mindanao are likely to experience near normal rainfall conditions. Furthermore, surface air temperatures are predicted to be slightly warmer to warmer than average during the season.
PAGASA will continue to closely monitor the possible development of El Niño and updates shall be issued as appropriate. For further information, please contact the Climatology and Agrometeorology Division (CAD) at telephone numbers 434- 0955 or 435- 1675.
VICENTE B. MALANO, Ph.D.