JANUARY - JUNE 2017
Oceanic and atmospheric indicators had reached weak La Niña levels in October 2016 (PAGASA termed as borderline La Nina), but this was not sustained. However, La Niña-like conditions continue, as impacts have been seen in some flood- and landslide-prone areas in the country. A transition to El Nino Southern Oscillation (ENSO)-neutral condition is expected to occur by February 2017 which will likely continue until June 2017.
January — March 2017
The period is the peak of the Northeast (NE) monsoon season, locally known as "Amihan". Tropical cyclone activity is however at its minimum. Weather systems that may affect the country are the NE monsoon, tail-end of a cold front, trough of low pressure areas (LPAs), Intertropical Convergence Zone (ITCZ), easterlies, ridge of high pressure area (HPA) and one (1) or two (2) tropical cyclones that are likely to develop/enter the Philippine Area of Responsibility (PAR).
Surface air temperatures are expected to be slightly cooler than average in mountainous Luzon while slightly warmer than average over the rest of the country. Surges of cold temperature are also expected during the season (January to February).
Rainfall outlook for January to March 2017 indicates that most parts of the country will likely experience near to above normal rainfall conditions. Impacts of La Nifia-like conditions will still prevail that may potentially trigger floods/flashfloods and landslides over vulnerable areas and storm surges over vulnerable coastal communities. Gradual weakening of the NE monsoon may begin towards the end of February or early March.
April to June 2017
The period covers the gradual shift of the season from NE monsoon to Southwest (SW) monsoon. The weather systems that may affect the country are the easterlies, ridge of high pressure area (HPA), ITCZ, LPAs, SW monsoon and two (2) to four (4) tropical cyclones. Warmer than average surface air temperatures are also expected during the season.
The month of April signals the transition towards the SW monsoon season. Significant changes in rainfall pattern will be observed as the normal onset of the rainy season is expected to commence by the second half of May to early June for areas under Climate Type I (western section of the country).
In general, near normal rainfall conditions are expected during the period.
PAGASA will continue to closely monitor these conditions and regular updates and advisories shall be issued as appropriate. Meanwhile, concerned agencies are advised to take precautionary measures to mitigate the potential adverse impacts of La Nina-like conditions. For further information, please contact the Climatology and Agrometeorology Division (CAD) at telephone numbers 434-0955 or 4351675.
VICENTE B. MALANO, Ph.D.