Tropical Cyclone Wind Signals: Difference between revisions - Wikipedia
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|36 hours
|'''''Minimal to minor threat to life and property'''''
* House of poor construction (e.g., [[Lumber|wood]] [[Framing (construction)|frame]], [[bamboo]], makeshift), old dilapidated structures, and other structures made of light materials will suffer minimal to minor damage.
* Some [[Musa (genus)|banana]] and similar plants are tilted, while twigs of small trees may sway with the wind. [[Oryza sativa|Rice]] crops, especially those in flowering and ripening stages, may suffer some damage.
* Minimal disruption to [[Transportation in the Philippines|public transportation]]
* Classes in the [[preschool]] level are automatically cancelled or suspended.
|Tropical depressions (TD) and stronger
|-
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|24 hours
|'''''Minor to moderate threat to life and property'''''
* Minor to moderate damage may occur to makeshift or old dilapidated structures, and other structures made of light materials. Houses of poor and average construction (e.g., unreinforced [[Concrete masonry unit|CHB]]/[[masonry]], mixed [[Lumber|timber]]-CHB) may receive minor [[roof]] damage.
* Unsecured, exposed lightweight items may become projectiles which may cause additional damage.
* Some [[Overhead power line|electrical wires]] may be blown down, resulting in local [[Power outage|power outages]].
* Minor to moderate disruption to public transportation.
* Most banana and similar plants are tilted, with some stooped or downed. Some small trees blow over, with twigs and branches of frail trees broken. Considerable damage is likely to rice and other similar crops, especially those in flowering and ripening stages
* Classes in the [[preschool]] and [[elementary education|elementary]] levels are automatically cancelled or suspended.
|Tropical storms (TS) and stronger
|-
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|18 hours
|'''''Moderate to significant threat to life and property'''''
* Makeshift or old, dilapidated structures, and other structures made of light materials may suffer substantial damage. Houses of poor or average construction will have considerateconsiderable roof damage, some blown-out windows, and/or partial wall damage. Well-constructed houses (e.g., reinforced/pre-cast CHB, reinforced [[concrete]] [[Moment-resisting frame|moment frame]]) may suffer minimal to minor roof damage.
* [[Warehouse|Warehouses]] and other buildings in [[Industrial park|industrial parks]] may suffer minor to moderate damage.
* Unsecured, exposed outdoor items of light to moderate weight may become projectiles, causing additional damage or injuries.
* Many areas may suffer power outages with numerous downed [[Overhead power line|power lines]] and [[Utility pole|posts]]. Minimal to minor disruption in [[Telecommunications in the Philippines|telecommunications]] and [[Drinking water|potable water supply]].
* Moderate to significant disruption to public transportation
* Some small trees., most banana and similar plants, and a few large trees are downed or broken. Rice and other similar crops, especially those in flowering and ripening stages may suffer heavy damage
* Classes in the [[preschool]], [[Elementary school|elementary]] and [[high school]] (including [[senior high school]]) levels are automatically cancelled or suspended.
|Severe tropical storms (STS) and stronger
|-
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* Severe damage will occur to makeshift or old, dilapidated of light structures, and other structures made of light materials. Houses of poor or average construction may receive major damage, including complete roof failure and possible wall collapse; a few may suffer severe damage.
* Most well-constructed houses may suffer minor to moderate roof damage, with some houses experiencing major roof failure; blown out windows are also likely.
* Failure of [[Aluminium|aluminum]] and [[steel]] roofs and coverings may occur in buildings at industrial parks.
* Some [[glass]] in most high-rise office buildings may be blown out; a few of these buildings may have minor to moderate damage and higher proportion of blown-out windows due to swaying.
* Considerable airborne debris will be generated and may cause damage, injury, and possible fatalities.
* Near total loss of power supply and telecommunications due to numerous downed power lines, poles, and cellular towers. Diminished availability of potable water supply is also likely.
* Significant to severe disruption to public transportation.
* Significant damage to banana and similar plants. Most small trees and some large trees will be broken, defoliated, or uprooted. Almost total damage to rice and other crops
* Classes in all [[Education in the Philippines|educational levels]] (including [[colleges]] and [[universities]]) are automatically cancelled or suspended.
|Typhoons (TY) and stronger
|-
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* Severe to catastrophic damage is expected to houses of poor or average construction, makeshift or old, dilapidated structures, and other structures made of light materials. Well-constructed houses may suffer substantial roof and wall failure or damage.
* Many industrial buildings will be destroyed, with only few receiving partial roof and wall damage.
* Most windows will be blown out in high-rise office buildings; moderate structural damage is possible due to swaying. Most, if not all, billboards and signs will be destroyed.
* Extensive damage will be cause by airborne debris. People, pets, and livestock exposed to the wind are at great risk of injury or death.
* Electricity, potable water supply, and telecommunications will be unavailable for prolonged periods due to significant disruption in infrastructure.
* Prolonged significant to severe disruption to public transportation.
* Vast majority of the trees will be broken, defoliated, or unrooted. Banana and similar plants will be extensively damaged. Only few trees, plants, and crops will survive.
* Most, if not all billboards and signs will be destroyed.
|Super typhoons (STY)
|}
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| caption2 = The wind signals enumerated in the same bulletin are visualized in this color-coded map which PAGASA publishes in its official website and social media accounts.
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Whenever a [[tropical cyclone]] forms inside or enters the [[Philippine Area of Responsibility]] (PAR), the [[Philippine Atmospheric, Geophysical, and Astronomical Services Administration]] (PAGASA) commences the release of ''Tropical Cyclone Bulletins'' (TCB) to inform the general public of the cyclone's location, intensity, movement, circulation radius and its forecast track and intensity for at most 72 hours. The TCB also contains a plain-text discussion of the hazards threatening land and coastal waters and the PAGASA's track and intensity outlook for the cyclone.
PAGASA activates the five-tiered ''Tropical Cyclone Wind Signal'' (TCWS) system once it is determined that the tropical cyclone inside the PAR is going to directly affect the Philippines and its outermost [[Tropical cyclone windspeed climatology#Winds in tropical cyclones|cyclonic winds]] is at least 36 hours away from reaching the nearest Philippine landmass. Wind signals under the TCWS system are hoisted primarily at [[Cities of the Philippines|city]]/[[Municipalities of the Philippines|municipal]] or [[Provinces of the Philippines|province]] level. An exception to this is [[Metro Manila]], which is collectively placed under a single wind signal level. All TCWS signal levels in effect in various localities affected or to be affected by tropical cyclone winds are enumerated in each TCB issuance, including the escalation, de-escalation or lifting of such signal levels. Wind signals are hoisted and updated (escalated, de-escalated or lifted) usually in regular time intervals coinciding with the release of a TCB:<ref>{{Cite web |last=Perez |first=Chris |date=October 26, 2018 |title=Public Weather Forecast Issued at 4:00 AM October 26, 2018 |url=https://www.youtube.com/watch?v=zYg0OqiKIY0&t=663s |access-date=August 24, 2022 |website=YouTube |publisher=Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA)}}</ref>
*6-hourly TCB issuance: when TCWS signals levels have been raised as the tropical cyclone approaches the Philippine landmass (5:00{{nbsp}}a.m./p.m. and 11:00{{nbsp}}a.m./p.m. [[Philippine Standard Time|PHT]]).
*3-hourly TCB issuance: when (a) the tropical cyclone is about to make [[landfall]] within the next 24 hours; (b) during land crossing and directly after land crossing when the tropical cyclone startstarts to move over water away from land; (c) the tropical cyclone remains offshore but is significantly close to the landmass, warranting the activation of TCWS signals (2:00{{nbsp}}a.m./p.m., 5:00{{nbsp}}a.m./p.m., 8:00{{nbsp}}a.m./p.m. and 11:00{{nbsp}}a.m./p.m. PHT).
TCBs can also be released only twice a day (12-hourly) when the tropical cyclone is too far away that it does not affect the Philippine landmass (whether or not the tropical cyclone is approaching the landmass), in which case no TCWS signals are raised.
Contrary to common misconception, the purpose of the TCWS system is to warn the public of the threat of tropical cyclone winds (and its associated hazards on land and sea); it does not include rainfall (and its associated hazards such as flooding and landslides) induced by tropical cyclones. There are other weather warning systems already in place for rainfall, such as Rainfall Advisories for light to moderate rainfall and the Heavy Rainfall Warning System (HR-WS) for heavy and/or continuous rainfall during rain-intensive weather events including tropical cyclones.▼
[[File:All Tropical Cyclone Wind Signals (TCWS) issued due to Typhoon Noru (Karding), 23–26 September 2022.gif|thumb|310px|The progression of Tropical Cyclone Wind Signal issuances for [[Typhoon Noru|Typhoon Noru (Karding)]] in September 23–26, 2022. Notice how wind signal levels are escalated/downgraded and how the overall area with wind signals expand/contract as the typhoon moved through Luzon Island.]]
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For example, winds of 39–61 km/h is expected to occur within the next 36 hours when a specific locality is initially put under TCWS #1 due to an approaching tropical cyclone; thus, that locality has at least 36 hours to prepare before such winds arrive or start to occur. When the wind signal in the same locality is escalated to #2, the public has at least 24 hours left to prepare or brace themselves before their locality is struck by winds of 62–88 km/h.
▲Contrary to common misconception and as implied by its name, the purpose of the TCWS system is to warn the public of the threat of tropical cyclone ''winds'', (andincluding its associated hazards and/or impacts on land and sea. As detailed in the [[Tropical Cyclone Wind Signals#Tropical Cyclone wind signal levels|table]] above, PAGASA devised the TCWS system such that each of the five warning signals stands for specific levels of severity of the impacts of tropical cyclone winds (increasing from minimal/minor impacts in TCWS #1 up to catastrophic impacts in TCWS #5);, itespecially on damages to infrastructure and agriculture due to high winds and the risk of injury or death due to building failure or airborne debris. The scope of the TCWS system does not include [[Rain|rainfall]] (and its associated hazards such as [[Flood|flooding]] and [[Landslide|landslides]]) induced by tropical cyclones. TherePAGASA arehas other weather warning systems already in place for rainfall, such as Rainfall Advisories for light to moderate rainfall and the Heavy Rainfall Warning System (HR-WS) for heavy and/or continuous rainfall during rain-intensive weather events including tropical cyclones.
Wind signals under the TCWS system are hoisted primarily at [[Cities of the Philippines|city]]/[[Municipalities of the Philippines|municipal]] or [[Provinces of the Philippines|province]] level. An exception to this is [[Metro Manila]], which is collectively placed under a single wind signal level.
The TCWS system is often the basis for [[weather-related cancellation|suspension of work, classes and transportation]] in the Philippines due to tropical cyclones, albeit this is not explicitly stated since it is already outside PAGASA's purview. The currently applied protocol by the country's [[Department of Education (Philippines)|Department of Education]] (DepEd) indicates that classes (from kindergarten to Grade 12) and work are automatically suspended in all [[Education in the Philippines|public elementary and secondary schools]] located in localities where the TCWS system (regardless of the warning level) is in effect due to a tropical cyclone.<ref>{{Cite web |author-link=Department of Education (Philippines)|date=September 1, 2022 |title=DepEd Order No. 37, s. 2022 (Guidelines on the cancellation or suspension of classes and work in schools in the event of natural disasters, power outages/power interruptions and other calamities)|url=https://www.deped.gov.ph/wp-content/uploads/2022/09/DO_s2022_037.pdf |url-status=live |archive-url=https://web.archive.org/web/20240111150717/https://www.deped.gov.ph/wp-content/uploads/2022/09/DO_s2022_037.pdf |archive-date=January 11, 2024 |access-date=January 11, 2024}}</ref> However, current protocols implemented by the [[Commission on Higher Education (Philippines)|Commission on Higher Education]] (CHED) stipulate that [[Higher education in the Philippines|state universities and colleges]] are allowed to suspend classes and work due to tropical cyclones only in the following three cases: (1) if the institution's locality has been placed under Wind Signal #3, (2) if the local chief executive, i.e. municipal or city mayor, declares the suspension of work and classes in all levels, (3) if the institution's head, i.e. president, headmaster or dean, declares the suspension of work and classes.<ref>{{Cite web |author-link=Commission on Higher Education (Philippines)|date=June 1, 2012|title=CHED Memorandum Order No. 15, s. 2012|url=https://ched.gov.ph/wp-content/uploads/2017/10/CMO-No.15-s2012.pdf|url-status=live|access-date=January 11, 2024}}</ref><ref>{{Cite news |last=Hernando-Malipot |first=Merlina |date=September 28, 2022 |title=CHED clarifies cancellation of classes in public, private schools in tertiary level |url=https://mb.com.ph/2022/09/28/ched-clarifies-cancellation-of-classes-in-public-private-in-tertiary-level |url-status=live |archive-url=https://archive.md/L8EUl |archive-date=January 11, 2024 |access-date=January 11, 2024 |work=[[Manila Bulletin]]}}</ref> On the other hand, the country's [[Philippine Coast Guard|Coast Guard]] decrees that generally all [[Watercraft|vessels]] are prohibited to venture out to sea when the TCWS (also regardless of the warning level) is in effect along its route and points of departure and destination, with strict exemptions applied only to few vessel types.<ref>{{Cite web |author-link=Philippine Coast Guard|date=March 23, 2023|title=Memorandum Circular No. 02-23 (Revised guidelines on movement of vessels during heavy weather)|url=https://coastguard.gov.ph/images/2023_Files/MC/0223_Revised_Heavy_Weather.pdf|url-status=live|access-date=January 11, 2024|archive-url=https://web.archive.org/web/20240111151738/https://coastguard.gov.ph/images/2023_Files/MC/0223_Revised_Heavy_Weather.pdf|archive-date=January 11, 2024}}</ref>
== History ==