|PAGASA Yellow, Orange and RED Color Code Warning System|
PAGASA releases new advisory for the implementation of new color coded warning signal system as of August 9, 2012.
GREEN warning signal was changed to ORANGE warning signal which means preparedness and alert for possible evacuation in your area.
PAGASA Color Coded Warning Signal Alert System
|PAGASA Rainfall Warning Alert System Color Code Meaning and Rainfall Values (in mm).|
New alert system is created by PAGASA to warn public of incoming rainfall volume brought by weather disturbance.
Unlike for Public Storm Warning Signal number 1, 2 and 3 during Typhoons that measures the strength of wind, the new system is color coded which means possible rainfall volume that will likely to continue for the next 3 hours in a certain area specified by PAGASA.
YELLOW Warning Signal
Rainfall Volume: 7.5 - 15 mm per hour (Heavy) within 1 hour has fallen
Effects: Flooding is possible in low lying areas and near river channels
What to do: Community Awareness - Monitor the weather condition and wait for next PAGASA weather advisory
ORANGE Warning Signal
Rainfall Volume: more than 15 - 30 mm per hour (Intense rains) within 1 hour has fallen
Effects: Flooding is threatening in low lying areas and near river channels
What to do: Community Preparedness - Alert for possible evacuation
RED Warning Signal
Rainfall Volume: 30+ mm per hour (Torrential) within 1 hour has fallen
Effects: Flooding is expected in low lying areas. Take precautionary measures
What to do: Community Emergency - Evacuation
What Does mm/hr or millimeter per hour of Rain Means?
Rain or Rainfall is measured in length per unit time. PAGASA uses mm/hr or millimeter per hour in it's color code warning signal alert system and what does it mean?
1 mm/hr of rainfall means 1 millimeter of rainfall height in 1 m2 area per hour. To fully understand, I draw a figure in the above page showing 30+ mm/hr in a box with length = 1 meter, width = 1 meter and height = 1 meter.
For a volume of 1 m3, it takes 33 hours to fully filled it with rainfall 30+ mm (RED warning signal). In addition, lets see the equivalence of 1mm to liters of water.
1 mm/h = 1 Liter of water in 1 m2 area per hour
15 mm/h = 15 Liters of water in 1 m2 area per hour
30 mm/h = 30 Liters of water in 1 m2 area per hour
So, for Yellow warning, people can experience 7.5 - 15 Liters per hour of rainfall volume per 1 m2 area, for Orange warning 15 - 30 Liters per hour of rainfall volume per 1 m2 area and 30+ Liters per hour for RED warning alert.
Rainfall Volume Conversion to Liters
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