Understanding Philippine Weather Warnings

Philippine Weather

Richard Cepeda Go

At this time of the year, the rainy season of the Philippines is just beginning to gain momentum. The season begins late May, strengthens by August and begins to wane by October. Now, do not worry because the sun does still show itself regularly. Just plan your activities keeping in mind that there will be periods of rain that can range from simple showers to full blown storms (which can be deadly for the unprepared).

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) issues weather forecasts and warnings thru multi-media such as TV, radio, newspapers and the internet. In the last few years, they have invested in upgrading their equipment to the point that they are quite accurate.

You will hear laymen refer to any storm as a “bagyo” although purists say the word refers to typhoons or tropical cyclones. In a normal year, around 19 tropical cyclones (typhoons) or storms enter the Philippine Area of Responsibility (PAR) and of these 6 to 9 usually make landfall. This year appears more active as 5 bagyos are forecasted to enter the PAR this July.

PAGASA releases warnings as Public Storm Warning Signals. (The main concern here is the potential destructive power of the tropical cyclone winds.) PSWS are raised when an area (in the Philippines only) is soon to be hit. As a tropical cyclone gets stronger and/or gets closer to an area, the warning is upgraded to a higher one. If it weakens and/or gets farther, it is downgraded to a lower signal or the area will have no storm signal.

Public Storm Warning Signals (PSWS):

  1. PSWS #1 – 30 km/h (19 mph) to 60 km/h (37 mph) winds expected within 36 hours. (If a tropical cyclone forms very close to the area, a shorter lead time is posted on the warning bulletin.)
  2. PSWS #2 – (Tropical Storm) Winds of 61 km/h (38 mph) to 120 km/h (75 mph) expected within the next 24 hours.
  3. PSWS #3 – (Typhoon) 121 km/h (75 mph) to 170 km/h (110 mph) winds expected within the next 18 hours.
  4. PSWS #4 – (Typhoon) 171 km/h (106 mph) to 220 km/h (140 mph) winds expected within 12 hours.
  5. PSWS #5 – (Super Typhoon) Winds stronger than 220 km/h (140 mph) are expected within 12 hours. PAGASA uses a color coding system to alert for flooding due to rainfall.

Flood alerts under the heavy rainfall warning system:

  1. YELLOW rainfall advisory -the expected amount of rainfall is 7.5 mm to 15 mm within one hour and is likely to continue. Possible flooding in low-lying areas.
  2. ORANGE rainfall advisory -rainfall is between 15 mm and 30 mm within one hour. Definite threat of flooding in the area.
  3. RED rainfall advisory -downpours constitute an emergency. When observed rainfall is more than 30 mm within one hour or if rainfall has continued for the past three hours and is more than 65 mm. Serious flooding is seen. Be ready to evacuate to safety.

*All Local Government Units (LGUs) have identified evacuation areas to be used in case of flooding. These include barangay multi-purpose courts

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