Pagasa unveils color coding for rain alerts




Is it going to rain today? The weather bureau will deliver the answer to this age-old question in yellow, green or red.

The Philippine Atmospheric, Geophysical  and Astronomical Services Administration (Pagasa) on Tuesday unveiled a color-coded rainfall alert system and a thunderstorm warning system for Metro Manila, a first for the country.

The new warning system should help communities and local governments  prepare for landslides, flash floods and river spills that could necessitate evacuation, Pagasa said.

Under the heavy rainfall warning system, a yellow warning is raised when the expected rainfall amount is between 7.5 mm to 15 mm within one hour and likely to continue.

Communities given this advisory are advised to be aware of the weather condition and warned that flooding may be possible in low-lying areas.

The green alert is raised in areas where rainfall is between 15 mm to 30 mm within one hour. Flooding is a definite threat in communities under the green alert.

A red alert is issued when downpours constitute an emergency, Pagasa said. This is raised 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.

When Pagasa raises this warning, communities should be prepared to respond. It means serious flooding is seen and that residents should be ready to evacuate to safety.

Thunderstorms alert

The alert system for thunderstorms, which produces isolated rain showers for short durations, specifies the likelihood of the formation of this weather condition over a certain area.

It will be raised when thunderstorm formation is likely within the next 12 hours and when it threatens a specific area within the next two hours.

All these alert systems will be disseminated through SMS, Twitter, the Pagasa website  and faxed advisories.

In the case of tropical storms, Pagasa will issue two warnings that would give a better picture of the weather conditions over certain areas.

One will constitute the public storm warning signals, which is based on the cyclone’s wind strength, and the other will be for rainfall amount.

“The rains from a cyclone are not symmetric. Some areas will have more rains than others,” said Pagasa Administrator Nathaniel Servando.

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  • Loggnat

    They should go by percentage (%) chance of rain to give them some leeway and be more realistic. Nobody can really forecast where the exact place the rain will fall. It is only possible to forecast the chances of rainfall along the path of an existing raincloud. It is a good ‘palusot’ too. If they predicted 80% chances of rain and it did not rain, they can always say that it fell under the 20% of no rain. And for thunderstorms, just make a severe weather warning followed by exact areas that will be affected. For flood, a possible flood warning and a evacuation alert if there is an imminent danger of severe flooding. That should be simple enough for everybody to understand and prevents misunderstanding because some people will probably be confuse on which color means and what mm of rain will fall. =))

  • panis

    i truly appreciate the effort of pag-asa for adapting such information system on weather for the Philippine condition… more power to you guys sana start na ito ng mas maganda pang weather information system natin…. please look into adapting such system for the benefit of farming communities…for harvesting schedule and drying grains (corn and palay) malaking bagay ang info kung uulan o hindi… malaki ang impact nito sa kita ng farmers. thanks

  • panis

    ooop sorry PAGASA not-pag-asa…

  • Tito Bobot

    Assigning the “Green” color for this application is wrong. Green color normally use for positive statement. They should go for yellow, orange, red where red color signify the worst condition.

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