Climate Outlook (MAY – SEPTEMBER 2017) JOSEPH BASCONCILLO Climate Monitoring and Prediction Section (CLIMPS) Climatology and Agrometeorology Division (cad) Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) Updated: 24 April 2017

INTERNATIONAL PREDICTION CENTERS GLOBAL ADVISORIES INTERNATIONAL PREDICTION CENTERS SUMMARY CPC/ International Research Institute (IRI), USA As of : 13 April 2017 ENSO-neutral conditions are favored to continue through at least the NH spring 2017 (MAM), with increasing chances for El Niño development by late summer and fall. ENSO Alert System Status: Not Active Bureau of Meteorology (BOM)-Australia As of : 11 April 2017 El Niño WATCH continues; eastern tropical Pacific waters warm The tropical Pacific remains neutral with respect to the El Niño-Southern Oscillation (ENSO); however, there are signs that El Niño may develop in 2017. Tokyo Climate Center/JMA -Japan As of: 10 April 2017 Although sea surface temperatures (SSTs) have been above normal in the eastern equatorial Pacific, ENSO neutral conditions continue. The probability of occurrence of El Niño event by the end of boreal summer is 50%. based from SSTA averaged over NINO.3 (5°N-5°S, 150°W-90°W) APEC Climate Center, Busan, S. Korea As of : 24 March 2017 persistent positive temperature anomaly across the equatorial and off-equatorial Pacific and Atlantic with the positive El Niño-Southern Oscillation (ENSO) phase.  It is important to note that El Niño and La Niña (ENSO) are not the only factors that drive global climate patterns, but ENSO is the dominant mode of climate variability that affect our rainfall pattern Also, there is typically high uncertainty in forecasts made at this time of the year because of spring predictability barrier. Seven of eight models indicate that sea surface temperatures will exceed El Niño thresholds during the second half of 2017. However, some caution must be exercised as models have lower accuracy at this time of year. Spring Predictability Barrier,” which is when the models have a harder time making accurate forecasts.  WMO-LC-LRFMME based in S. Korea as of:15 February 2017 Second half of 2016 - tropical Pacific Ocean surface temperatures were at borderline weak La Niña/cool-neutral levels; ENSO prediction: Neutral-ENSO conditions and El Niño both possible during the second half of 2017. PAGASA: ENSO-neutral conditions are present in the tropical Pacific and favored to continue through at least March-April-May 2017 season. Though majority of the models predict reaching El Nino threshold during the second half of 2017, there is high uncertainty in forecast made at this time of the year.

Niño Region SST Departures (oC) Recent Evolution Recent conditions The latest weekly SST departures are: Apr. 3 Apr. 10 Apr. 17 Apr. 24 Niño 4 0.0 0.3 Niño 3.4 0.2 0.5 Niño 3 0.8 0.7 0.6 Niño 1+2 1.8 0.9 1.1 Niño 4 -0.3ºC Niño 3.4 -0.2ºC Niño 3 0.4ºC Niño 1+2 2.1ºC During the last 4 weeks, the SST has warmed in all Nino regions, Nino 4 or Nino west started from negative anomaly but still within ENSO-neutrall levels

PAGASA ENSO Alert System Status is INACTIVE

Monthly Mean Rainfall Distribution Neutral El Niño La Niña Wetter in the western part Wetter in the eastern part

Monthly Rainfall Average by Climate Type

Actual Rainfall for April 1-23, 2017 Normal RR(mm) (1981-2010) Actual Rainfall Observed (mm) % Normal

WEATHER SYSTEMS THAT MAY AFFECT THE COUNTRY DURING THE PERIOD (May-September 2017) Easterlies Thunderstorms Inter tropical Convergence Zone (ITCZ) Ridge of High Pressure Area (HPA) Low Pressure Areas (LPAs) Tropical Cyclones SW monsoon (around May-June)

About our Rainfall Maps… Forecast Rainfall WBN - More than 60% reduction from the normal rainfall BN - 21-60% reduction from normal rainfall NN – less than 20% reduction from normal rainfall AN – surplus of rainfall

Monthly Rainfall Forecast Updated: April 3, 2017 Normal (mm) (1981-2010) MAY 2017 Forecast (mm) % Normal 0 Province/s to be affected 80 Province/s to be affected

Monthly Rainfall Forecast Updated: April 3, 2017 Normal (mm) (1981-2010) JUNE 2017 Forecast (mm) % Normal 0 Province/s to be affected 77 Province/s to be affected 3 Province/s to be affected

Monthly Rainfall Forecast Updated: April 3, 2017 Normal (mm) (1981-2010) JULY 2017 Forecast (mm) % Normal 0 Province/s to be affected 5 Province/s to be affected 59 Province/s to be affected 16 Province/s to be affected

Monthly Rainfall Forecast Updated: April 3, 2017 Normal (mm) (1981-2010) AUGUST 2017 Forecast (mm) % Normal 0 Province/s to be affected 7 Province/s to be affected 71 Province/s to be affected 2 Province/s to be affected

Monthly Rainfall Forecast Updated: April 3, 2017 Normal (mm) (1981-2010) SEPTEMBER 2017 Forecast (mm) % Normal 0 Province/s to be affected 1 Province/s to be affected 62 Province/s to be affected 17 Province/s to be affected

Monthly Rainfall Forecast Rainfall Condition (based on recent conditions): MAY– SEPTEMBER 2017 Rainfall Forecast: April– below normal to way below normal (Luzon and Western Visayas) near normal rainfall ( Eastern Visayas and Mindanao) May – near normal generally near normal rainfall June – near normal rainfall with patches of above normal RR in Luzon July- near to above normal (Luzon); below to near normal (Visayas and Mindanao) Aug-Sep – near to above normal (Visayas and Mindanao); near to below normal (Western section of Luzon)

RAINFALL PROBABILITY FORECAST Lighter shades indicate high uncertainty in the forecast that a category is going to happen

Lighter shades indicate high uncertainty in the forecast that a category is going to happen

MONTHLY AVERAGE TEMPERATURE FORECAST MAY– SEPTEMBER 2017 Slightly warmer Slightly warmer warmer Slightly cooler cooler Slightly warmer Slightly warmer Slightly cooler Slightly warmer Slightly warmer Slightly warmer Slightly cooler Slightly cooler Slightly warmer Slightly warmer Slightly warmer

Wet & Dry Days Forecast Wet day is defined as a day with ≥ 1 mm of rain. WET DAY FORECAST – being issued from May – January Dry day is defined as a day with < 1 mm of rain. DRY DAY FORECAST – being issued from February to April

WET DAY FORECAST

Tropical Cyclone Forecast 8 – 12 TCs from April-September 2017 MONTH Number of TC MAY 2017 1 or 2 JUNE 2017 1 to 2 JULY 2017 2 to 3 AUGUST 2017 2 to 4 SEPTEMBER 2017 8-12 8 – 12 TCs from April-September 2017

Average tropical cyclone tracks (1948-2005) MAY 0-1 JUNE 1-2 JULY 2-4 AUGUST SEPT May June September July August

SUMMARY ENSO-neutral conditions are present in the tropical Pacific and favored to continue through at least March-April-May 2017 season; ENSO Alert System Status – INACTIVE Rainfall Forecast: Generally near normal

SUMMARY Slightly warmer than average surface temperature is expected over the coming months as the dry season just started; Normal onset of the rainy season (2nd half of May to 1st half of June) is expected for areas under Climate Type I (western sections of the country); 8 to 12 tropical cyclones may develop or enter the Philippine Area of Responsibility (PAR) during the forecast period.

MARAMING SALAMAT! (THANK YOU VERY MUCH) The Weather and Climate Authority MARAMING SALAMAT! (THANK YOU VERY MUCH)