Department of Science and Technology

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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
By Daisy F. Ortega
CLIMATOLOGY AGROMETEOROLOGY BRANCH December
1, 2005
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Weather Situation and Outlook
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  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.
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Weather Outlook in the Philippines December
2005   The Pacifics ENSO indicators strongly
suggest that near normal conditions are expected
to prevail up to the first quarter of 2006.   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
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Monthly Rainfall
November 1-27, 2005
Normal (mm)(1971-2000)
Actual (mm)
Normal
Below Normal
5 Above Normal

• 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 .

28 Way Below Normal
13 Near Normal
54 Below Normal
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Tropical Cyclones During the Month
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Total Rainfall Normal (mm)November
2005(1971-2000)Rainfall (mm)
Normal                      
                         
                         
                         
                         
                         
                         
                         
          
Attachment
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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
By Daisy F. Ortega
CLIMATOLOGY AGROMETEOROLOGY BRANCH December
1, 2005
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The Philippine Climate Classification (Modified
Coronas)
Type IV Climate
Rainfall more or less evenly distributed
throughout the year.
Type III Climate
Type III Climate
Seasons not very pronounced relatively dry from
Dec to Apr wet during the rest of the year.
Seasons not very pronounced relatively dry from
Dec to Apr wet during the rest of the year.
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GLOBAL CLIMATE CONDITIONS
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Current Update as of Nov. 16, 2005

• 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-2006.

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Making Decisions

• 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 ?

• When is this rainfall likely to occur ?

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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
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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- 181.7mm Normal
Value (1971- 2000) - 307.9 Percent Normal
(181.7/ 307.9 )100
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Normal RR 307.9mm (100)
Observed RR
59 (181.7mm)
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Station Name ILOILO For the Month of June
1988 Observed Rainfall- 483mm Normal Value
(1971- 2000) - 307.9 Percent Normal (483/
307.9) 100
156.9
307.9mm (100)
483mm (156.7)
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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.