EVERY time a storm enters the Philippine Area of Responsibility (PAR), one of the things we monitor is the Tropical Cyclone Wind Signal (TCWS) announcement. But what does the TCWS actually mean?

According to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), TCWS is a warning system used to alert residents of a certain area about the winds they may experience during a tropical cyclone.

The strength of winds is measured using the Beaufort Scale and may be experienced up to 36 hours from the time the signal was announced.

More specifically, a TCWS is accompanied by details such as wind strength, warning lead time or the number of hours before the expected wind threat, and its potential impact in the area.

To understand more about TCWS, here is what each signify according to the PAGASA website:

TCWS No. 1:

Wind threat: 39 to 61km/hr

Warning lead time: 36 hours

Issued for Tropical Depression (TD) or higher

Potential impacts:

• Structures made out of light materials may suffer minimal to minor damage.
• Plants like banana may tilt; twigs of small trees may sway; and flowering and ripening rice crops may suffer some damage.
• Minimal disruption to public transportation.

TCWS No. 2:

Wind threat: 62 to 88km/hr

Warning lead time: 24 hours

Issued for Tropical Storm (TS) or higher

Potential impacts:

• Structures made out of light materials may suffer minor to moderate damage; houses of poor to average construction may have minor roof damage.
• Untethered lightweight items may be flown by the strong winds and cause damage.
• Plants like banana are tilted, possibly stooped or felled; small trees may be blown, with twigs and branches broken; flowering and ripening rice crops and similar crops may suffer considerable damage.
• Local power outage may occur due to some electrical wires being blown by the winds.
• Minor to moderate disruption to public transportation.

TCWS No. 3:

Wind threat: 89 to 117km/hr

Warning lead time: 18 hours

Issued for Sever Tropical Storm (STS) or higher

Potential impacts:

• Structures made out of light materials may suffer substantial damage; houses of poor to average construction may have considerate amount of roof damage, blown-out windows, and/or partial wall damage; well-constructed structures may suffer minimal to minor roof damage.
• Industrial buildings may suffer minor to moderate damage.
• Untethered outdoor light to moderately weighted items may be blown by the strong winds and cause damage or injuries.
• Banana and similar plants, as well as small trees and few large trees may be felled or broken. Rice and similar crops may suffer heavy damage.
• Power lines and posts may fall and cause power outages in many areas. Telecommunications may experience minimal to minor disruption, as well as water supply.
• Moderate to significant disruption to public transportation.

TCWS No. 4:

Wind threat: 118 to 184km/hr

Warning lead time: 12 hours

Issued for Typhoon (TY) or higher

Potential impacts: 

• Structures made out of light materials may suffer severe damage; houses of poor to average construction may have major to severe damage (roof damage and wall collapse); well-constructed structures may suffer minor to moderate roof damage and blown-out windows
• Industrial buildings may suffer aluminium and steel roof failure.
• Glasses in high-rise buildings may blow out.
• Untethered outdoor items may cause damage, injuries, even fatalities.
• Banana and similar plants may suffer significant damage; small and large trees may be broken, felled, or uprooted; almost total damage to rice and similar crops.
• Near total loss of power supply and telecommunications because of fallen power lines, poles, and cell towers; potable water supply may be scarce.
• Significant to severe disruption to public transportation.

TCWS No. 5:

Wind threat: 185km/hr or higher

Warning lead time: 12 hours

Issued for Super Typhoon (STY) or higher

Potential impacts: 

• Structures made out of light materials may suffer severe to catastrophic damage; well-constructed structures may suffer substantial roof damage and wall failure or damage.
• Industrial buildings may be destroyed.
• High-rise buildings may suffer blow out in most of its glasses, as well as moderate structural damage.
• Untethered outdoor items may cause extensive damage, injuries, even fatalities. People and animals outdoors are at great risk for injury or death.
• Majority of trees may be broken, felled, or uprooted; banana and similar plants may suffer extensive damage; few crops and plants will survive.
• Prolonged loss of power supply, telecommunications, and water supply due to infrastructure damages.
• Prolonged significant to severe disruption to public transportation.