Wednesday, August 8, 2012

PAGASA RAINFALL Color Coded Warning Alert System Meaning

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.

Sources:
PAGASA
Rainfall Volume Conversion to Liters


Related Articles:
PAGASA List of Typhoon Names for 2013, 2017 and 2021
PAGASA Typhoon PABLO Deaths and Damages - Deadliest in 2012
DOE Energy Plan for 2012-2030 - Aims to Mitigate Climate Change
DOST Project NOAH - Now Available on Mobile Android
EO26 NGP - PNOY Largest Reforestation Program
New PAGASA Rain Color Coded Warning Signal Alert System
PAGASA Habagat Brings 80% of ONDOY'S Rain Volume
How PAGASA, DOST Project NOAH Works? - A Review
PAGASA Most Advanced Doppler Radar is Operational in Catanduanes
Typhoon Sendong - Philippines Most Deadliest Typhoon for 2011

4 comments:

Henry said...

Mabuti nakaisip sila ng ganito, sana madali rin maintindihan ng mga tao :D

GbSb said...

That's right Henry, PAGASA change Green to Orange to easily understand by public but they are only using international standard colors.

The warning should also translated to layman's term for public info.

Louie Enclona said...

Quote: "For a volume of 1 m3, it takes 3 hours to fully filled (sic) it with rainfall 30+ mm (RED warning signal)."

Don't you think that's way too fast? At a rate of 30mm/hr, a height of 1m (or 1000mm) can be reached in about 33 hrs, not 3. Typographical? :)

GbSb said...

Thanks for a keen eye, it should be approximately 33 hours not 3.

Post a Comment

Related Posts Plugin for WordPress, Blogger...