Super typhoon and Signal Number 5, now part of PAGASA’s terminology

In meteorology, the life cycle of a tropical cyclone starts with cloud clusters that develop into a low pressure area (LPA). Once this LPA intensifies, it becomes a tropical cyclone, the general term for “bagyo.” This tropical cyclone is then classified based on its wind speeds.

Through the years, the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) has used three official tropical cyclone categories: Tropical Depression, Tropical Storm and Typhoon.

Yolanda, with the international name Haiyan, which made its landfall in the country last November 2013, is remembered as one of the strongest typhoons in recent years. Largely affected was the Visayas area, where storm surges caused massive destruction to lives and properties.

Days before the first anniversary of Yolanda, the Typhoon Committee of PAGASA decided to revise the classification of tropical cyclones, adding the category “Super Typhoon” on its list. However, this memo said that the revision will be applied in 2015.

In May 2015, by virtue of Memorandum Circular No.3, PAGASA officially declared that Super Typhoon is now part of the tropical cyclone classification.

11231990_923634734326734_2045169675_o

The new tropical cyclone classifications are as follows:

Tropical Depression (TD) has maximum sustained winds of up to 61 kilometers per hour, equivalent to 33 nautical miles per hour or more.

Tropical Storm (TS) packs 62 to 117 kilometers per hour. Meanwhile, a Severe Tropical Storm will only be applicable for the International Warning for Shipping, and will not be used for general public dissemination unlike the other categories.

Typhoon (TY) is used in identifying a tropical cyclone with wind speeds 118 to 220 kilometers per hour or 64 to 120 knots.

Super Typhoon (STY) has maximum sustained winds of more than 220 kilometers per hour. STY is as powerful as 120 nautical miles per hour or more.

Since there are changes in cyclone categories, the public storm warning signals (PSWS) were revised as well. According to PAGASA, the country has experienced a number of destructive tropical cyclones in the past ten years. These cyclones were mostly in Typhoon category with maximum sustained winds of more than 220 kilometers per hour. During the passage of Yolanda, the usual four-level warning system of the PSWS was found inadequate.

In line with this, Signal Number 5 now becomes part of PAGASA’s warning.

11301429_923868047636736_1921571878_n

Once PSWS #5 is hoisted, residents must prepare for winds of more than 220 kilometers per hour in at least 12 hours. This can cause very heavy to widespread damage to the affected areas.

PAGASA explained that the revision aims to emphasize the intensity of a tropical cyclone and the threat of its impacts. Using the term “Super Typhoon” and “Signal Number 5” will also escalate the sense of urgency and community response in times of an approaching storm.

Amor Larrosa

Amor Larrosa

Weather Reporter at Panahon TV

Amor is a Mass Communication graduate of the Far Eastern University. During her college years, she enjoyed performing onstage for FEU Theater Guild, her school's official theater organization. As a Panahon TV reporter, she wants to inspire others by sharing her knowledge about climate action and disaster preparedness. Recently, she has started producing her own segments, most of which tackled said issues. In 2015, Amor attended the World Meteorological Organization’s training for Broadcasting in Vietnam, wherein she learned about the most effective ways of delivering climate and weather information to the public. Apart from reporting on the television and radio, she also hosts parties, weddings, birthdays and sports-related events.