In the Philippinestropical cyclones (typhoons) are called bagyo.[1] Tropical cyclones entering the Philippine Area of Responsibility are given a local name by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), which also raises public storm signal warnings as deemed necessary.[2][3] Around 19 tropical cyclones or storms enter the Philippine Area of Responsibility in a typical year and of these usually 6 to 9 make landfall.[4][5]

The deadliest tropical cyclone to impact the Philippines as of November 2013 was Haiyan, known in the Philippines as Typhoon Yolanda. The thirtieth named storm, thirteenth typhoon, and fifth super-typhoon of the 2013 Pacific typhoon season, Haiyan originated as an area of low pressure east-southeast of Pohnpei in the western Pacific Ocean on November 2. Tracking generally westward, the disturbance steadily developed within an environment of light wind shear and warm sea surface temperatures, becoming a tropical depression early the following day. After becoming a tropical storm and attaining the name Haiyan at 0000 UTC on November 4, the system began a period of rapid intensification that brought it to typhoon intensity by 1800 UTC on November 5. With an expanding and deepening central dense overcast and clear eye visible on satellite, the Joint Typhoon Warning Center (JTWC) upgraded Haiyan to a super typhoon—a typhoon in which maximum sustained winds attain or exceed 240 km/h (150 mph)—early on November 6. After entering PAGASA’s region of responsibility, the JTWC upgraded Haiyan to a Category 5 equivalent on the Saffir-Simpson hurricane wind scale.

The Philippines is the most-exposed large country in the world to tropical cyclones, and it has even affected settlement patterns in the northern islands; for example, the eastern coast of Luzon is very sparsely populated.

Etymology and naming conventions

Bagyo

The term bagyo, a Filipino word meaning typhoon arose after a 1911 storm in the city of Baguio had a record rainfall of 46 inches within a 24-hour period.[1][6][7]

Names of storms

Since the middle of the 20th Century, American forecasters have named tropical storms after people, originally using only female names.[8] Philippine forecasters from the now-PAGASA started assigning Filipino names to storms in 1963 following the American practice, using names of people in alphabetical order, from A to Z.[8] Beginning in January 2000, the World Meteorological Organization“s Typhoon Committee began assigning names to storms nominated by the 14 Asian countries who are members with each country getting 2 to 3 a year.[8] These names, unlike the American and Filipino traditions, are not names for people exclusively but include flowers, animals, food, etc. and they are not in alphabetical order by name but rather in alphabetical order by the country that nominated the name.[8] After January 2000, Filipino forecasters continued their tradition of naming storms that enter the Philippines Area of Responsibility and so there are often two names for each storm, the PAGASA name and the so-called “international name”.

Variability in activity

On an annual time scale, activity reaches a minimum in May, before increasing steadily through June, and spiking from July through September, with August being the most active month for tropical cyclones in the Philippines. Activity falls off significantly in October.[9] The most active season, since 1945, for tropical cyclone strikes on the island archipelago was 1993 when nineteen tropical cyclones moved through the country (though there were 36 storms that were named by PAGASA).[10] There was only one tropical cyclone which moved through the Philippines in 1958.[11] The most frequently impacted areas of the Philippines by tropical cyclones are northern Luzon and eastern Visayas.[12] A ten year average of satellite determined precipitation showed that at least 30 percent of the annual rainfall in the northern Philippines could be traced to tropical cyclones, while the southern islands receive less than 10 percent of their annual rainfall from tropical cyclones.[13]

Public Storm Warning Signals

Signal #1
winds of 30–60 km/h (20-35 mph) are expected to occur within 36 hours
Signal #2
winds of 60–100 km/h (40-65 mph) are expected to occur within 24 hours
Signal #3
winds of 100–185 km/h, (65-115 mph) are expected to occur within 18 hours.
Signal #4
winds of at least 185 km/h, (115 mph) are expected to occur within 12 hours.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) releases tropical cyclone warnings in the form of Public Storm Warning Signals.[3] An area having a storm signal may be under:

  • PSWS #1 – Tropical cyclone winds of 30 km/h (19 mph) to 60 km/h (37 mph) are expected within the next 36 hours. (Note: If a tropical cyclone forms very close to the area, then a shorter lead time is seen on the warning bulletin.)
  • PSWS #2 – Tropical cyclone winds of 60 km/h (37 mph) to 100 km/h (62 mph) are expected within the next 24 hours.
  • PSWS #3 – Tropical cyclone winds of 100 km/h (62 mph) to 185 km/h (115 mph) are expected within the next 18 hours.
  • PSWS #4 – Tropical cyclone winds of greater than 185 km/h (115 mph) are expected within 12 hours.

These storm signals are usually raised when an area (in the Philippines only) is about to be hit by a tropical cyclone. As a tropical cyclone gains strength and/or gets nearer to an area having a storm signal, the warning may be upgraded to a higher one in that particular area (e.g. a signal #1 warning for an area may be increased to signal #3). Conversely, as a tropical cyclone weakens and/or gets farther to an area, it may be downgraded to a lower signal or may be lifted (that is, an area will have no storm signal).

Classes for preschool are canceled when Signal #1 is in effect. High school classes and below are canceled under Signal #2 and classes for colleges and universities and below are canceled under Signal #3 and Signal #4.

Deadliest Cyclones

Thelma/Uring approaching the Philippines

Rank[14] Storm Dates of impact Deaths
1 Yolanda/Haiyan 2013, November 08 1774 (initial as of November 11, 2013)
2 Thelma/Uring 1991 1991, November 4–7 5,101-8,000[15]
3 Angela Typhoon 1867, September 22 1,800[16]
4 Winnie 2004 2004, November 27–30 1,593
5 October 1897 Typhoon 1897, October 7 1,500[16]
6 Ike/Nitang 1984 1984, September 3–6 1,492
7 Fengshen/Frank 2008 2008, June 20–23 1,410
8 Durian/Reming 2006 2006, November 29-December 1 1,399
9 Washi/Sendong 2011 2011, December 16–17 1,268
10 Bopha/Pablo 2012 2012, December 2–9 1,246

Most destructive

Parma/Pepeng approaching the Philippines at peak strength

Costliest Philippine typhoons
Rank Names Dates of impact PHP USD Ref
1 Bopha, (Pablo) December 2 -9, 2012 42.2 billion 1.04 billion [17]
2 Parma, (Pepeng) October 2–10, 2009 27.3 billion 608 million [18]
3 Nesat, (Pedring) September 26–28, 2011 15 billion 333 million [19]
4 Fengshen, (Frank) June 20 -23, 2008 13.5 billion 301 million [20]
5 Ketsana, (Ondoy) September 25 -27, 2009 11 billion 244 million [18]
6 Mike, (Ruping) November 10 – 14, 1990 10.8 billion 241 million [21]
7 Angela, (Rosing) October 30 – November 4, 1995 10.8 billion 241 million [21]
8 Flo, (Kadiang) October 2 – October 6, 1993 8.75 billion 195 million [21]
9 Megi (Juan) October 18 – October 21, 2010 8.32 billion 193 million [22]
10 Babs, (Loleng) October 20 – 23 1998 6.79 billion 151 million [21]

Wettest recorded tropical cyclones

Wettest tropical cyclonethe Philippines
Highest known recorded totals
Precipitation Storm Location Ref
Rank mm in
1 2210.0 87.01 July 1911 cyclone Baguio City [23]
2 1216.0 47.86 Carla 1967 Baguio City [23]
3 1085.8 42.45 Utor/Feria 2001 Baguio City [24]
4 1012.7 39.87 Mindulle/Igme 2004 [25]
5 994.6 39.16 Zeb/Iliang 1998 Baguio City [25]
6 902.0 35.51 Kujira/Dante 2009 [26]
7 869.6 34.24 Dinah/Openg 1977 Western Luzon [27]
8 817.9 32.20 Elaine 1974 Baguio City [28]
9 782.3 30.80 Bess/Susang 1974 Baguio City [29]
10 723.0 29.46 Linfa/Chedeng 2003 Tondoligan Park, Dagupan, Pangasinan [30]

Source: en.wikipedia.org