2009 Pacific typhoon season

2009 Pacific typhoon season
Basin	WPac
Year	2009
First storm formed	May 3, 2009
Last storm dissipated	December 7, 2009
Strongest storm name	Nida
Strongest storm pressure	905 hPa
Total depressions	41
Total storms	22
Total hurricanes	13
Total intense	5 (unofficial)

2009 Pacific typhoon season was an above-average western North Pacific tropical cyclone season characterized by multiple powerful typhoons that affected East Asia, Southeast Asia, and the western Pacific islands. The season produced notable storms including Morakot, Ketsana (known regionally in the Philippines as Ondoy), Parma (Pepeng), Nida, and Melor. Responses and consequences involved international organizations and national agencies such as the United Nations, Red Cross, World Bank, PAGASA, JMA, and JTWC.

Seasonal summary

The season developed amid influences from the El Niño–Southern Oscillation and the Madden–Julian oscillation interacting with the monsoon trough, leading to early-season activity including disturbances tracked by HKO, CMA, KMA, and regional observatories. Major events included rapid intensification episodes observed in Nida near the Philippine Sea and prolonged landfall sequences for Parma interacting with Melor through the Fujiwhara effect. The season saw coordination between emergency management bodies such as the NDRRMC, Ministry of Health, Labour and Welfare, MCDEM, and metropolitan authorities in Manila, Taipei, Tokyo, Seoul, and Hong Kong. International relief involved USAID, ECHO, and bilateral aid from countries including Japan, China, United States, and Australia.

Systems

Numerous tropical cyclones tracked across the basin with operational designations from agencies such as PAGASA, JMA, JTWC, and regional centers in Hong Kong, Macau, and Vietnam. Notable systems included Linfa, Nida, Lupit, Ketsana, Vamco, Molave, Goni, Morakot, Parma, Melor, Melor's complex evolution, and late-season systems like Nangka and Mirinae. Tracking products and warnings were issued by NOAA, U.S. Navy, U.S. Air Force, and regional meteorological institutes in Philippines, Japan, China, Vietnam, and Thailand.

Storm naming and monitoring

Naming protocols followed conventions established by the ESCAP/WMO Typhoon Committee, with names submitted by member nations including Japan, North Korea, South Korea, Philippines, China, Thailand, Vietnam, Malaysia, Brunei, Cambodia, and Laos. PAGASA assigned local names such as Ondoy and Pepeng when systems entered the Philippine Area of Responsibility, while the JTWC used numeric designations (e.g., Tropical Depression 17W). The JMA served as the Regional Specialized Meteorological Center (RSMC) for the western North Pacific, issuing official intensity estimates and names, alongside regional advisories by HKO, CMA, KMA, PAGASA, and the VMHA.

Impact and statistics

The season caused widespread impacts across the Philippines, Taiwan, China, Vietnam, Japan, South Korea, North Korea, Laos, Cambodia, Thailand, Malaysia, and Indonesia. Ketsana produced catastrophic flooding in Metro Manila and river basins including the Pasig River and the Marikina River, prompting mass evacuations coordinated by NDRRMC and international appeals to the OCHA. Morakot caused extreme rainfall and landslides in Taiwan leading to major responses by the Executive Yuan, the Republic of China Armed Forces, and relief from the Red Cross Society of China. Economic losses were assessed by World Bank and national finance ministries, with agriculture and infrastructure damage reported by DA and transportation ministries. Casualties, displacement, and infrastructure damage prompted post-storm assessments by WMO, ADB, IFRC, and national disaster agencies.

Seasonal forecasts and climatology

Pre-season and intra-seasonal outlooks were produced by agencies including JMA, CPC, HKO, PAGASA, and academic groups at institutions such as IRI, University of Hawaii, Kyoto University, MRI, and Lamont–Doherty Earth Observatory. Forecasts considered indices like El Niño, SOI, and sea surface temperature anomalies measured by Argo floats and NOAA satellites such as GOES and Himawari. Climatological analyses compared activity to historical seasons including 1997, 2006, and 2008, evaluating metrics like accumulated cyclone energy (ACE) and basin-wide ACE used by WMO researchers and regional climatologists.

Aftermath and records

After the season, reviews and post-event studies were undertaken by JMA, JTWC, PAGASA, NOAA, WMO, and national research centers. Several names were retired by the ESCAP/WMO Typhoon Committee owing to severe impacts, prompting replacement names from contributing members such as Cambodia, Laos, and Brunei. Scientific studies published by researchers at NOAA, IRI, University of Tokyo, National Taiwan University, Chinese Academy of Sciences, and Academia Sinica examined rapid intensification, orographic rainfall enhancement over Taiwan and the Philippine archipelago, and disaster risk reduction lessons learned by NDRRMC, Ministry of Public Safety and Security, and municipal governments in Manila and Kaohsiung. The season influenced subsequent preparedness planning by organizations including UNDP, ADB, and national ministries of interior across affected states.

Category:Pacific typhoon seasons