Department of Science and Technology Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) Science Garden, Agham Rd., Diliman Quezon City, Philippines Weather Situation / Outlook For November/December 2005 CLIMATOLOGY & AGROMETEOROLOGY BRANCH December 1, 2005 By: Daisy F. Ortega

Weather Situation and Outlook Weather Situation Condition of the CEEP Weather Systems RR distribution Prevailing average maximum and minimum temperature Weather Outlook Forecast on the following: Weather Systems and no. of tropical cyclones Rainfall and temperature ranges on major areas

Weather Situation in the Philippines November 1-27, 2005 A continuation of ENSO neutral conditions was observed over the Pacific Nino basin. It is consistent with earlier assessments that the central and eastern equatorial Pacific region will remain at near normal condition. The Philippines was affected by the intertropical convergence zone (ITCZ), easterly wave, cold front, active low pressure area, the northeast monsoon, and the passage of two(2) tropical cyclones. Tropical Depression (TD) “Ondoy” (November 8-11, 2005) made landfall over the vicinity of Baler Aurora and exited towards the Ilocos while Typhoon (TY) “Pepeng” (November 14-20, 2005) traversed over the eastern section of Luzon before it dissipated into an active Low Pressure Area. These two tropical cyclones contributed significantly to the rainfall of some northern provinces of Luzon. Based on the latest rainfall analysis, the observed rainfall was near normal over Aurora, Cagayan, Mountain Province, Kalinga, Ifugao, Camarines Provinces, Bohol, Agusan Provinces, and Surigao del Sur while the provinces of Quirino and Isabela experienced above normal rainfall conditions. The rest of the country have below to way below rainfall conditions. The recorded average air temperature were as follows; mountainous areas of Luzon, from 14 to 23 C, over the mountains of Mindanao, from 18 to 28. In lowland areas of Luzon, 20 to 32, Visayas 23 to 31, and Mindanao 22 to 33. Warmer than normal air temperatures were experienced in most parts of the country.

Weather Outlook in the Philippines December 2005 The Pacific’s ENSO indicators strongly suggest that near normal conditions are expected to prevail up to the first quarter of It is therefore expected that the Philippines will most likely be affected by the northeast monsoon, intertropical convergence zone (ITCZ), easterly wave, cold front, and the passage of one (1) tropical cyclone. Rainfall condition are expected to be mostly normal except for some provinces of Sarangani, Cotabato, Sultan Kudarat, Southern parts of Lanao, Maguindanao, Pangasinan and some areas of Metro Manila will likely experience above normal condition. Below normal to way below normal rainfall is expected over provinces of Cavite, Batangas, Northern Mindoro, Bataan, southern part of Zambales, and some parts of Tarlac. Air temperatures are expected to cool as we approach the winter season of the northern hemisphere. Cold air masses brought about by the northeast monsoon interacting with the cold front may cause air temperature to drip further especially at night time and will be distinctly felt in areas of northern Luzon particularly in mountain ranges. Outdoor traditional gatherings preparatory for Christmas celebration may expect to get affected by occasional rainshowers brought about by rain causing weather system associated with the movement of the diffused tail end of a cold front

Monthly Rainfall November 1-27, 2005 Actual (mm)% Normal Normal (mm) ( ) NOVEMBER ACTUAL RAINFALL Below normal rainfall in most parts of the country except CAR, nortnheastern part of Luzon and some parts of northeastern Mindanao where near normal and above normal rainfall were experienced in these areas. 5 % Above Normal Below Normal 13% Near Normal 54 % Below Normal 28 % Way Below Normal

Tropical Cyclones During the Month

Total Rainfall Normal (mm) November 2005 ( ) Rainfall (mm) % Normal Attachment

Monthly Rainfall Forecast Ensemble December 2005 Forecast (mm) % Normal Normal (mm) ( ) December 2005 % Normal Normal (mm) ( )

Department of Science and Technology Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) Science Garden, Agham Rd., Diliman Quezon City, Philippines Seasonal Rainfall Forecast in Malaybalay, Bukidnon Using RAINMAN OND 2005 CLIMATOLOGY & AGROMETEOROLOGY BRANCH December 1, 2005 By: Daisy F. Ortega

The Philippine Climate Classification (Modified Coronas) Type III Climate Type IV Climate Seasons not very pronounced; relatively dry from Dec to Apr & wet during the rest of the year. Rainfall more or less evenly distributed throughout the year. Type III Climate Seasons not very pronounced; relatively dry from Dec to Apr & wet during the rest of the year.

The patterns of anomalous SST, atmospheric winds and precipitation over the equatorial Pacific indicate ENSO-neutral condition. Recent SSTs, low-level winds, precipitation, and sea level pressure are near average over the tropical Pacific. The recent trends in SSTs and subsurface temperature anomalies indicate that conditions in the tropical Pacific are likely to remain ENSO-neutral during the next several months. Most of the statistical and coupled model forecasts indicate that ENSO-neutral conditions will prevail through mid Current Update as of Nov. 16, 2005

Making Decisions When is this rainfall likely to occur ? What amount of rainfall is needed to achieve best results? What is the probability of receiving the amount? What is the ENSO outlook for this year ? What is the average likely amount of rainfall expected ?

Thank you

NORMAL - The average value of a meteorological element (ex. rainfall) over a fixed period of years ( 30 yrs) that is recognized as standard for the country and element concerned. Example. Name of Station: ILOILO Month: June

Percent Normal Comparing total observed rainfall to the normal value. This is telling you what part of the normal value is the observed rainfall. Express in percent. Example: Station Name: ILOILO For the Month of June 1983 Observed Rainfall mm Normal Value ( ) Percent Normal = (181.7/ )*100 = 59 % Normal RR 307.9mm (100%) 59% (181.7mm) Observed RR

Station Name: ILOILO For the Month of June 1988 Observed Rainfall- 483mm Normal Value ( ) Percent Normal = (483/ 307.9) *100 = 156.9% 307.9mm (100%) 483mm (156.7%)

RAINFALL CONDITIONS Above Normal - Condition when the Percent Normal of the observed rainfall in a particular place is above 120% Near Normal - Condition when the Percent Normal of the observed rainfall in a particular place is between 81%- 120%. Below Normal - Condition when the Percent Normal of the observed rainfall in a particular place is between 41%- 80%.