Gale Warning
Issued at: 5:00 PM TODAY , 16 May 2020
Gale Warning # 8 (Final)
For: MODERATE TO STRONG winds associated with TROPICAL STORM "ambo" [VONGFONG]

Gale Warning in PDF file

Weather Advisory
Issued at: 12:00 PM 2020 May 10
Weather Advisory in PDF file

General Flood Advisories - Regional
 General Flood Advisory issued as of 7 PM, 20 August 2018


Monthly Climate Assessment and Outlook (July-August 2018)

Issued: 06 August 2018

Monthly Rainfall Forecast
RAINFALL FORECAST  (September 2018 - February 2019) 
UPDATED: 29 August 2018 (next update September 26, 2018)

Regional Rainfall Forecast
Issued: 29 August 2018
Valid for: September 2018 - February 2019
Farm Weather Forecast and Advisories
ISSUED: 8 AM,  FRIDAY,  MAY 24, 2019
, 2019
FWFA:  N0. 19-144

Ten-Day Regional Agri-Weather Information
DEKAD NO. 15   MAY 21 - 31, 2019
The weather systems that will affect the whole country are the frontal system, easterlies, ridge of high pressure area, intertropical convergence zone (ITCZ) and low pressure area (LPA).

Seasonal Climate Outlook
Issued:  13 July 2018
FOR July - December 2018

Astronomical Diary
Issue for October 2018
The October Orionids meteor shower will be active from October 17-25, 2017.

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Gaudioso R. Tabamo

The intertropical convergence zone is defined by different writers in different ways and it has been discussed under many different names. There is also difference of opinion as to whether rainfall occurs in separate patches or as a continuous belt along the major wind discontinuity or whether it is dispersed over a narrow zone or a wider zone in the general vicinity of the wind discontinuity. In general, it is implied from the literature that the more prominent wind discontinuity at some level or levels in the tropical atmosphere is sometimes associated with close or distant precipitation.

The association of precipitation with wind discontinuity has been implicitly accepted without proof, and the lines or zones which have been drawn on published synoptic charts appear to be a composite representation of rainfall and wind-field. To determine whether the major wind discontinuity is associated in some way with areas of rainfall and whether there is a zone of rainfall along the wind discontinuity or whether rainfall is dispersed over a wide zone, completely separate analyses of wind-fields and of the rainfall charts over the Philippines have been made in the present study and these have been related graphically. For determination of the wind field there are 11 pilot balloon stations and 46 synoptic observing stations, approximately 70 miles apart, which regularly report the direction of movement of the lowest and middle clouds at various levels. The scarcity of observations of wind-speed make computations of convergence impracticable. Therefore, the wind discontinuities which emerged from the analyses were really the assymptote of confluence in the streamlines in the lower 2000 to 4500 feet of the atmopshere, so that it was not practicable to take into account any slope in the surface of separation between two airstreams in the present study. Since the analyses show that the wind discontinuity can undergo considerable displacement in one day and because near the coast its position may also be affected by the difference between land and sea temperatures, analyses of the wind field have been made twice daily, at 0000 GMT and 1200 GMT, respectively.

For the determination of the rainfall patterns, rainfall observations are available at 46 synoptic stations in the Philippines, representing an average spacing of approximately 70 miles between stations. It was realized that, with an observing network over land, the diurnal temperature variation might have an influence on rainfall, and therefore separate precipitation charts for the periods 1800-0600 GMT and 0600-1800 GMT (each of which includes a time of wind observations) have been analyzed so that any diurnal effect would be discernible and, if appreciable, could be investigated. The analyses have been extended over the surrounding seas with the aid of cloud pictures from weather satellites.

The period examined in this study is June to October, 1964-1967, and the major wind discontinuity is discernible over the Philippines on 473 of the 12-hourly wind charts drawn during this period.

It was found that, in the majority of cases, rainfall was greater at one or both sides of the wind discontinuity than at the discontinuity itself. Since the most likely explanation of this is that the surface of wind-discontinuity possesses slope, a new investigation requiring special observations over a long period has been proposed. Another proposal for further investigation has been made in relation to the diurnal variation of rainfall.