User:Chlod/Scripts/Deputy/testpages/TCWS

The Tropical Cyclone Wind Signals (TCWS, or simply storm signals or signals) are storm signals issued by the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) when a storm is inside or near the Philippine Area of Responsibility. TCWS signals are issued for specific localities depending on the expected strength of winds within a given amount of time (known as the lead time). The TCWS is a tiered system that has five levels, with higher numbers associated with higher wind speeds and shorter lead times.

Issuance
Tropical Cyclone Wind Signals are raised usually by province or city (with the exception of Metro Manila) by the PAGASA when a tropical cyclone is within the Philippine Area of Responsibility. On some occasions, signals may be raised for a specific municipality or city, depending on the storm. The TCWS is a tiered system goes from Signals No. 1 to 5, with higher signals meaning higher wind speeds and shorter lead times. The signal raised for a specific locality may change depending on the cyclone wind speed, intensity, extent of winds, direction, and movement speed. TCWS signals are raised and lowered whenever Tropical Cyclone Bulletins are released by the PAGASA, which varies in 3-hour, 6-hour, and 12-hour intervals, depending on a storm's intensity and distance from the Philippines.

The lead time determines the number of hours from the first time a signal is raised until an area is hit by the signal's expected wind strength. This means a storm signal may be hoisted in a locality hours before the impact of the winds are felt, in order to warn citizens of an impending storm.

Public Storm Warning Signals
In the 1950's, the PAGASA (then the Philippine Weather Bureau) maintained a warning system which included 10 levels, from Public Storm Warning Signals (PSWS) #1 to #10. It was revised in the 1970s to include only three levels. A storm must have a maximum sustained wind speed of less than 63 kph for PSWS #1 (equivalent to a tropical depression), 64 to 117 kph for PSWS #2 (equivalent to a tropical storm) and at least 118 kph for PSWS #3 (equivalent to a typhoon).

A fourth signal was added in 1997 to accommodate stronger typhoons. In addition to this, signals also included a lead time which determined when an area should expect the winds for a given signal. The PAGASA later expanded this to included details on a signal's impact and precautionary measures to be taken.

Tropical Cyclone Warning System
Following the onslaught of Typhoon Haiyan in 2013, discussion on the revision of the PSWS started, as PSWS #4 was deemed inadequate for strong typhoons. The Tropical Cyclone Warning Signal (TCWS) system was launched in May 2015 to replace the PSWS. Signals No. 1 to 4 followed the Western Pacific tropical cyclone basin's Regional Specialized Meteorological Center's scale, the scale used by the Japan Meteorological Agency. A fifth signal, TCWS #5, was introduced for super typhoons designated by the PAGASA. TCWS #5 carried the same lead time as TCWS #4: 12 hours. The TCWS was then renamed to Tropical Cyclone Wind Signal in 2019 to give emphasis to winds rather than rains, flash floods, and landslides.

Shortly after the onslaught of Tropical Storm Megi, on March 23, 2022, the PAGASA revised the TCWS system again. The Modified Tropical Cyclone Warning System was implemented due to indistinguishable damages between areas under TCWS #4 and TCWS #5, and to refocus TCWS #2, which were issued for both tropical storms and severe tropical storms, despite the possible significant change in cyclone strength between the two.