The MTC Typhoon Warning System (Un-Official)
This warning system has been devised for the region as deemed appropriate so that advance warnings can be given to areas to be affected by a storm. The series of warnings are governed by three words to describe the seriousness of the situation: "likely, possible and expected". These warnings are also given depending on the severity of the storm
Basic Elements of the Warning System
Tropical Cyclone Intensity
TROPICAL DEPRESSION - A defined, closed circulation with winds of less than 33kts (65kph) - Characterized by torrential rain TROPICAL STORM - A tropical cyclone with maximum sustained wind between 65 to 117kph - A severe tropical storm has been classified as having winds between 90 to 117 kph. TYPHOON - A tropical cyclone with maximum sustained wind between 117 to 215 kph - Category 1-3 typhoons fall into this category SUPER TYPHOON - A tropical cyclone with maximum sustained wind in excess of 215 kph - Category 4 and 5 typhoons are classified as such. |
Warning Parameters
Three parameters are considered in the posting of warnings. WIND RADIUS The area in which a certain wind velocity are to be experienced within a tropical cyclone TRACK PROBABILITY CIRCLE An area in which the storm center is to be expected in a given time. The circle increases in time as the forecast track error also increases over time, thus increasing the area at risk. STORM RAINBANDS Determined by satellite/radar, the swath of rainclouds to affect a certain area. Certain areas of the storm can dump heavier rain further from the center, thus areas not experiencing wind can suffer from heavy rain. This is now considered as tropical depressions and tropical storms as they have been proven and known to dump excessive rainfall. Examples are: Washi/Sendong in December 2011 -- Cagayan De Oro and Iligan Cities Ketsana/Ondoy in September 2009 -- Metro Manila and surrounding areas Thelma/Uring in November 1991 -- Ormoc City, the most killer flood in recent history. |
The MTC Warning System in detail
ADVISORY
- Means a tropical cyclone has formed in the Western Pacific Basin.
- There is a likelihood that the area can experience Tropical Storm conditions within 72 hours.
- Effects of the storm are plausible within a 72 hour period.
- Area is in the forecasted path of the storm after 72 hours from released bulletin and there is a likelihood that certain effects will be experienced by that time.
- When raised, areas concerned should monitor the progress of the storm. Public awareness should be started by now.
Gale Advisory - Gale force winds (30-60 kph) are likely within 72 hours, used for Tropical Depressions and enhanced monsoonal effects
Tropical Storm Advisory - There is a likelihood of experiencing Tropical Storm conditions (60-100 kph) within 72 hours
Typhoon Advisory - There is a likelihood of experiencing Typhoon conditions within 72 hours
Super Typhoon Advisory - There is a likelihood of experiencing winds exceeding 200kph within 72 hours
WATCH
- Means that the tropical cyclone is moving closer to the locality.
- There is a possibility that the area can experience Tropical Storm conditions within 48 hours.
- Storm effects are now being capable of occurring within a 48 hour period.
- When raised, areas concerned should continue to monitor the progress of the storm, and disaster preparations should be underway.
Gale Watch - Gale force winds (30-60 kph) are possible within 48 hours, used for Tropical Depressions and enhanced monsoonal effects
Tropical Storm Watch - Tropical Storm conditions (60-100 kph) are possible within 48 hours
Typhoon Watch - Typhoon conditions are possible within 48 hours. Watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds.
Super Typhoon Watch - Winds exceeding 200kph are possible within 48h. Watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds.
WARNING
- Means that a tropical cyclone is ABOUT TO or is NOW affecting the locality.
- Tropical Storm Conditions or higher is now expected in the area within 24 hours.
- Storm effects are about to or now occurring in the locality within the next 24 hours.
- When raised, areas concerned must have finished all preparations and be ready for the onset of conditions.
- Warnings of certain intensity will be raised on a given location when storm is to pass Closest Point of Approach (CPA) within 24 hours and location is certain to experience such storm effects associated with that intensity. (Example: Metro Manila is expected to experience Tropical Storm conditions upon typhoon's CPA within 24 hours, thus meriting a TROPICAL STORM WARNING. Other areas that will experience Typhoon conditions will merit a TYPHOON WARNING.)
- Warnings of certain intensity will still be raised on a given location even if worst possible conditions have already passed or the storm has already went past CPA and is still experiencing the storm effects associated with that intensity. (Example: Metro Manila has been hit by the Typhoon 6-12 hours past but is still experiencing Tropical Storm Conditions, thus meriting a TROPICAL STORM WARNING. Other areas currently experiencing the Typhoon conditions, will now merit the TYPHOON WARNING)
- Once certain storm conditions have died down, Warnings will be lifted, unless possible recurvature occurs.
Gale Warning - Gale force winds (30-60 kph) expected within 24 hours, used for Tropical Depressions and enhanced monsoonal effects
Tropical Storm Warning - Tropical Storm conditions expected within 24 hours.
Typhoon Warning - Typhoon conditions expected within 24 hours. Warning is issued 24 hours in advance of the anticipated onset of tropical-storm-force winds.
Super Typhoon Warning - Winds exceeding 200kph expected within 24 hours. Warning is issued 24 hours in advance of the anticipated onset of tropical-storm-force winds.
Rainstorm Watches and Warnings
These will be integrated into typhoon warnings or for such systems (SW or NE Monsoons, LPA's, Easterly Waves) that warrant raising of such watches and warnings.
Such will be raised in a locality should heavy to disastrous rainfall are about to occur or is now occurring in a certain location for a THREE HOUR PERIOD according to latest satellite data.
Such will be raised in a locality should heavy to disastrous rainfall are about to occur or is now occurring in a certain location for a THREE HOUR PERIOD according to latest satellite data.
- RAINSTORM WATCH - Heavy to flooding rain is possible within 24-36 hours.
- RAINSTORM WARNING - Heavy to flooding rain is now occurring or is to be expected within 12-24 hours.