Skip to main content

Typhoon Ondoy's Heavy Rainfall Explained

A lot of theories and speculations in the unusual heavy rainfall brought about by typhoon Ondoy, that cause massive flooding in Metro Manila and nearby areas. Here is the analysis of the Tropical Rain Measuring Mission (TRMM), a joint NASA and JAXA mission to monitor and study tropical rainfall.

Tropical Storm Ketsana Brings Record Flooding to Northern Philippines

The latest tropical system to the hit the Philippines, Tropical Storm Ketsana (known locally as "Tropical Storm Ondoy"), has resulted in record flooding in the capital of Manila on the island of Luzon in the northern Philippines. So far 140 people have died in the resultant flooding and mudslides with at least 32 more still missing. Ketsana began as a tropical depression in the west-central Philippine Sea on the morning of the 25th of September 2009 about 500 miles (~800 km) east-southeast of the central Luzon coast.

The system was upgraded to a minimal tropical storm on the evening of the 25th (morning of the 26th local time) as it tracked westward towards Luzon. Ketsana maintained minimal tropical storm intensity as it crossed central Luzon on the afternoon of the 26th (local time). The main deluge in the Manila area, located on the western side of Luzon, began around 8:00 am local time (00 UTC 26 September) even though the center of Ketsana had yet to make landfall on the eastern side of the island.

A record 13.43 inches of rain fell in Manila in the 6 hours between 8:00 am and 2:00 pm local time, which is equivalent to about a month's worth of rain for the area. The reason for the enhanced rainfall over on the Manila-side of the island as the storm approached was the interaction between Ketsana's low-level circulation and the seasonal southwest monsoon. The southwest monsoon comes about from the summertime heating of the Asian landmass. As warm air rises over the continent it induces low pressure as the surface, which draws air in from surrounding regions. The southwest monsoon typically runs from June to September in the Philippines and draws warm, humid air up from the southwest across the South China Sea and into the islands where it can interact with the topography. Ketsana's counterclockwise circulation enhanced the effect, which resulted in the torrential rains.

Typhoon Ondoy ll 21-28 Sep 09

Armed with both a passive microwave sensor and a space-borne precipitation radar, the primary objective of the Tropical Rainfall Measuring Mission satellite (better known as TRMM) is to measure rainfall from space. For increased coverage, TRMM can be used to calibrate rainfall estimates from other additional satellites. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA) at the NASA Goddard Space Flight Center is used to monitor rainfall over the global Tropics. TMPA rainfall totals are shown here for the 7-day period 21 to 28 September 2009 for the northern Philippines and the surrounding region. The highest rainfall totals occur in an east-west band over central Luzon, including Manila, south of storm's track (indicated by the solid black line). Amounts in this region are on the order of 375 mm (~15 inches, shown in dark yellow) to over 475 mm (~19 inches, shown in orange). The highest recorded amount near Manila was 585.5 mm (almost 24 inches).

After passing through the Philippines, Ketsana intensified into a minimal typhoon over the central South China Sea and is expected to make landfall along the central coast of Vietnam.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.
Images produced by Hal Pierce (SSAI/NASA GSFC) and captions by Steve Lang (SSAI/NASA GSFC)

Popular posts from this blog

Pantomina Lyrics And Music

Pantomina is Spanish for pantomime, movements imitating the courtship movements of the rooster and the hen. Ang mga babaye
Kung mayo pa nin agom
Maugay nin aga maugay nin hapon
Alagad kung sinda igua na nin agom
Maugay Octobre, Disyembreng sunudon. Ica palan, Nenang ang pinagsasabi
Magayon na burac sa lugar na ini
Magayon ang tindog malinig ang pisngi
Arin pa daw ang puso ang dai mawili. Can ica sadit pa sadit pa man aco
Si satuyang cawat magkudot-kudotan
Kinudot mo aco kinudot ta ca man
Sabi mo sa saco luhayluhaya man. Ang mga lalake
Hudyan sisaboot
Ang pinagsasabing ngarang pagcamoot
Kundi ang babayeng iyo minahilod
Akong minahiling can mga pangguyod.

Philippine Mining Act of 1995

With the recent issue of magnetite ore mining overwhemingly opposed by residents in the town of Bagamanoc and recently moved the mining site off the coast of Panganiban (Payo), I am compelled to post this Mining Act to serve as reference. "Republic Act No. 7942 or the Philippine Mining Act of 1995 (“Act”) is the governing law that regulates mineral resources development in the country. One of the primary objectives of this act is to revitalize the ailing Philippine mining industry by providing fiscal reforms and incentives and maintaining a viable inventory of mineral reserves to sustain the industry through the infusion of fresh capital through direct investments to finance mineral exploration and/or development activities. The original implementing rules and regulations of the Act was prepared in 1995, and was revised in 1996 under DENR Administrative Order 96 – 40, the revised implementing rules and regulations (RIRR). Collectively, the Act and its RIRR take into considerat…

Churches in Catanduanes

Catanduanes is composed of 11 municipalities, but there are 18 parishes distributed island wide. There are 3 parishes in the capital town Virac, 3 in Viga, 3 in Bato and 2 in San Andres. Although radical architectural changes have been made in many of the centuries old churches. From baroque to contemporary architecture and basic structural changes from coral stones to cement. Still many of the old practices and traditions are revered and observed up to this day. Happy Easter! Vicariate of Our Lady of the Immaculate Conception Vicar Forane: Rt. Rev. Msgr. Jose B. Molina, PA, VG Virac Cathedral (F-1755), Virac 4800 Catanduanes Population: 42,045; Catholics: 41,204 Titular: Our Lady of the Immaculate Conception, December 8 Parish Priest: Rev. Msgr. Jose B. Molina, PA, VG Parochial Vicars: Fr. Allan Martin Basilio, Fr. Joseph Saratan, Fr. Pascual Macuja (Retired, In Residence), Fr. Sid Jose Sanchez, Fr. Paul I. Isorena Cabugao (F-1911), Bato 4801 Catanduanes Population: 9,288; Catholics…

Catanduanes Watershed Forest Reserve

Site description: Catanduanes is an island of 182,300 ha which lies about 10 km off the tip of the Caramoan Peninsula in southern Luzon. The terrain on the island is hilly, particularly in the central portion, but the highest point only reaches just over 800 m. The substantial forests which remain in central Catanduanes are therefore all lowland dipterocarp in type, and are the largest remaining forest block in the whole of the Bicol Region. Forest is found above 490 m, and is estimated to cover a total of about 69,770 ha. It includes considerable areas of old growth dipterocarp forest (reported in 1997 to cover 5,876 ha), and closed-canopy forest in areas that show evidence of having been logged. These forest areas are the source of water for Catanduanes Province. One hydropower project is currently operational, that supplies power to urban areas of the island. The forest areas was proclaimed as a Watershed Reserve in 1987 because of these important function, the whole area is sta…

Catanduanes Remains Top Abaca-Producing Province - BM

Abaca-fiber production in the country’s top abaca-producing province from January to May 2009 went up by 22 percent to 8,646.32 metric tons (MT), said the Fiber Industry Development Authority (FIDA). FIDA noted that in January to May 2008, abaca farmers in Catanduanes produced 7,084.23 MT. The attached agency of the Department of Agriculture said a total of 16,231 farmers were involved in abaca production in the province in 2008. FIDA said the island province of Catanduanes is renowned as the “abaca capital of the Philippines.” The province is now the top producer of abaca fiber, has the largest area planted to abaca and has the biggest number of abaca farmer-producers in the Philippines. Joining Catanduanes as the country’s top 10 abaca-producing provinces are Southern Leyte, Leyte, Davao Oriental, Northern Samar, Davao del Sur, Surigao del Sur, Samar, Sulu and Sorsogon. FIDA said the province also adjusted its production for the year due to the projected slowdown in demand for…