Typhoon Nesat (2011)
Typhoon Nesat, known in the Philippines as Typhoon Pedring, was the most powerful tropical cyclone to directly impact China since 2008. It also struck the Philippines during late-September 2011, killing 98 people. It is the 17th named storm, the 11th severe tropical storm, the 7th typhoon and overall, the 30th tropical cyclone to be monitored by the Japan Meteorological Agency during the year. Nesat came exactly two years after Typhoon Ketsana made landfall in the Philippines as the most devastating typhoon in the 2009 Pacific typhoon season with a damage of United States dollar|1.09 billion and 747 fatalities. Nesat was also the first of twin tropical cyclones to batter the Philippines within one week during September 2011, the second was Nalgae.
The low pressure area that was to become Nesat developed on the evening of September 21, to the east-southeast of Palau. The Joint Typhoon Warning Center originally anticipated Nesat would become a Category 4 super typhoon on the Saffir–Simpson Hurricane Scale with winds exceeding . However, because of a cold anomaly, the system only reached a maximum 1-min sustained wind speed of making it a powerful Category 4 typhoon. Nesat made landfall over the Luzon region of the Philippines and the maximum sustained winds dropped to. The system continued to weaken with convective banding loosely wrapped into the partially exposed low-level circulation center. The winds continued to drop and eventually reached which made it a minimal typhoon on the SSHS. On September 29, by the time Nesat managed to re-develop a ragged eye, it made landfall over Wenchang in Hainan, China and started weakening again. Due to the rapid weakening, the JTWC ceased advisories on the storm, soon afterwards. Later that evening, the JMA downgraded Nesat to a tropical low over land and issued their final warning on the system.
As Nesat neared the Philippines, the local government ordered the evacuation of residents living in low-lying areas, cancelled flights and suspended classes on all levels. Several provinces were placed under Signal Number 2 and 1. China's flood control authority activated their emergency response system so that they can cope up with the upcoming typhoons Nesat, and Nalgae. The authority requested local governments in relevant areas to closely monitor both the typhoons and keep the public aware of what is happening. They initiated a level IV typhoon response program and sent two working teams to the provinces of Guangdong and Hainan so that they can assist people in all the preparations that they have to make. Ships were recalled, flight and ferry services were suspended and schools were shut as the strongest typhoon to directly impact Hainan in 2011 was approaching its final landfall. Macao's public transportation system was also suspended after typhoon signal No. 8 was hoisted by most local meteorological authorities. In Hong Kong, many functions and activities were canceled or postponed because of the fast approaching storm.
Early on September 27, Typhoon Nesat struck the Philippines with a maximum 1-min sustained wind speed of and killed four people after pinning them under a collapsed wall in Valenzuela. The residents of Manila had no other choice but to wade through waist-deep floodwaters, dodging branches and flying debris as the typhoon sent surging waves as tall as palm trees over seawalls, completely submerging neighborhoods. The typhoon made landfall before dawn triggering instant response. Officials in Albay province said that "About 112,000 people were ordered to leave their homes in five towns prone to flashfloods and landslides in central Albay province. Among the hardest hit provinces were Isabela and Aurora where most of the population was directly dependent on agriculture. Very similar to what happened after Typhoon Ketsana, a state of calamity was declared in Luzon in order to undertake an emergency procedure in order to ensure safe and timely water releases from the dams. Nesat approached China just one day after the preparations for it started. Because of the low strength of the storm, the damages from Nesat to China were expected to be near US$50 million. The typhoon then hit Vietnam and weakened into a tropical storm.
Meteorological history
During September 21, the Joint Typhoon Warning Center reported that a tropical disturbance had developed at the eastern end of a monsoon trough, about to the southeast of Melekeok on the island of Palau. The disturbance had a well defined low level circulation centre with convection flaring around it and was located in a region of moderate vertical windshear. Over the next 24 hours the depression moved towards the northeast, while gradually developing further. The Japan Meteorological Agency and the JTWC then reported during September 23 that the disturbance had developed into a tropical depression, with the latter designating it as Tropical Depression 20W.Early on September 24, the JMA further upgraded 20W to a tropical storm and named it Nesat. Nesat continued to drift west with expanding deep convection around the entire system and consolidating convection around the LLCC. The mid-level warm anomaly near the system continued to intensify and convective banding near the LLCC became more and more tighter. As a result, the JMA upgraded Nesat to a severe tropical storm on September 25. Nesat was originally expected to have undergone rapid intensification until September 25, but the JTWC later reported that the sea surface temperatures was a little less than expected and Nesat could not strengthen rapidly. However, Nesat was still strengthening. With an extremely well developed equatoward outflow, Nesat already had a windspeed of . Late on September 25, the JMA further upgraded Nesat to a typhoon.
On September 26, an image from Advanced Microwave Sounding Unit, a multi-channel microwave radiometer installed on meteorological satellites depicted that Nesat developed an eye like feature approximately east-northeast of Manila, Philippines. At that time, it had a 1-min sustained wind speed of with deep convection primarily over the western semicircle of the system. The system rapidly deepened and quickly developed a ragged eye and mesoscale anticyclone aloft generating an exceptionally excellent all-around outflow. Also, the system had a highly symmetric radial outflow. The JTWC originally anticipated Nesat to become a Category 5 super typhoon on the SSHS with winds exceeding . However, because of a cold anomaly, the system only reached a maximum 1-min sustained wind speed of, making it a minimum Category 4 typhoon.
Early on September 27, Nesat made landfall over the Luzon region of Philippines. As a result, the eyewall got eroded and the maximum 1-min sustained winds dropped to. The system approached land at nearly. However, later on that day, the LLCC started to get re-consolidated with convection as Nesat quickly moved west and re-emerged over water. At that time, it was located near the southern periphery of a deep layered subtropical steering ridge and moved towards the southwest and the winds further dropped to because of land interaction. Though the system has maintained overall central deep convection, subsidence persisted along the northwest quadrant which caused further drop in wind speed. Upper level analysis indicated that Nesat was to the south of a ridge axis in an area of moderate vertical wind shear. The system continued to weaken with convective banding loosely wrapped into the partially exposed LLCC. The winds continued to drop and eventually reached which made it a minimal typhoon on the SSHS. Though the weakening, Water vapour imagery showed that the typhoon was still maintaining excellent outflow towards the equator and improving outflow towards the pole. Nesat maintained a relatively large area of gale-force winds. Animated infrared satellite imagery depicted that the storm was expanding in size and convective banding continued to move further and further away from the LLCC. The LLCC was also relatively large, elongated and cloud free.
On September 29, by the time Nesat managed to re-develop a ragged eye, it made landfall over Wenchang in Hainan, China and started weakening again. Because of the poor shape and disorganization at the LLCC, the typhoon could only maintain a maximum 1-min sustained windspeed of. Even after the landfall, Nesat maintained vigorous convection all around the LLCC and did not weaken too much when compared to the reactions after the Philippine landfall. There was a sea-surface temperature of approximately and a slight vertical wind shear of near the system's center at that time. The JTWC anticipated the storm to gradually drift over the Gulf of Tonkin and make landfall over Vietnam with a 1-min sustained wind speed of at least. Early on September 30, Nesat made its final landfall over northern Vietnam with a 1-min sustained windspeed of and a well-defined, tightly wrapped LLCC, and soon it started weakening. Due to land interaction, the convection around the system started decaying rapidly. Due to the rapid weakening, the JTWC ceased advisories on the storm, soon afterwards. Later that evening, the JMA downgraded Nesat to a tropical low over land and issued their final warning on the system.
Preparations and impact
Philippines
As Nesat neared the Philippines, the Philippine government ordered the evacuation of residents living in low-lying areas, cancelled flights and suspended classes on all levels. By the morning of September 26, some 111,000 people in the flood-prone areas of the Albay Province were ordered to leave their homes. Nearly 63 flights were either delayed or cancelled due to the storm. The provinces of Albay, Catanduanes and the Camarines were placed under storm warning Signal Number 2 while the provinces of Metro Manila, Masbate, Marinduque, Batangas, Cavite, Bulacan, Pampanga and most of the Northern Luzon provinces were placed under storm warning Signal Number 1. Even though Manila was placed in Storm Signal 2, many universities, like the University of the Philippines Diliman & Manila and Polytechnic University of the Philippines, Main Campus, suspended classes.Early on September 27, Typhoon Nesat struck the Philippines with a maximum 1-min sustained wind speed of and killed four people after pinning them under a collapsed wall in Valenzuela. The typhoon pounded the Luzon region of the Philippines triggering flash floods, cutting power and halting daily activity in the capital Manila. The Philippine Stock Exchange and US embassy were forced to close due to the strong winds and heavy rains. The residents of Manila had no other choice but to wade through waist-deep floodwaters, dodging branches and flying debris as the typhoon sent surging waves as tall as palm trees over seawalls completely submerging neighborhoods. By the evening of September 27, at least 7 people were reported to be killed and most of them in metropolitan Manila, a place already battered by heavy monsoonal rains. A motorcyclist in the city reported that "It's flooded everywhere. We don’t have a place to go for shelter. Even my motorcycle got filled with water". He was one of the thousands stranded by fast-rising flood in the city. Similar to Tulane University during Hurricane Katrina, the Ospital ng Maynila Medical Center moved patients from its ground floor which was flooded with neck-deep waters. Hospital generators were flooded and the building had no power once the typhoon arrived. Soldiers and police in trucks moved thousands of residents, most importantly the women and the children away from the Baseco shanty town after many houses were washed away in the storm surge and floodwaters brought by Nesat. The typhoon made landfall before dawn triggering instant response.
Nearly thirty-seven percent of Manila Electric Company's service area was left without power after high winds and heavy rains toppled power lines. A company spokeswoman reported that "About 1.9 million customers of the nation's biggest power retailer are still without electricity. That's about 39 percent of its 4.9 million customers, compared with 44 percent who were without power at midday." Also, in Malabon, Navotas and Valenzuela the Manila Electric power company shut down power to prevent any accidents. Dina Lomotan, the company spokesman said that "Manila Electric will try to restore power as conditions permit, prioritizing areas not directly affected by the storm." President Benigno Aquino III said "I have been in touch with Secretaries Soliman, Gazmin, and Almendras. I have instructed the Executive Secretary to compile information from National Disaster Risk Reduction and Management Council and to inform our people of conditions, as well as of government efforts to mitigate the effects of the storm." He also said "I am in constant touch with the members of my cabinet, and the Executive Secretary has been instructed to keep me and the public informed of conditions pertaining as well as mitigation efforts". On September 28, the death toll from Nesat was put at 18 and the number of missing at 35 after the day-long rain and winds. The National Disaster Risk Reduction and Management Council chief Benito Ramos said, "We are focusing on trying to get power and telecommunications services today, and work crews have also fanned out to repair and clear 61 road networks across Luzon damaged by landslides, debris and floods". The extremely high storm surges brought by Nesat crashed over seawalls, flooding a hospital, a five-star hotel, and the US embassy near Manila. As more power lines were downed, nearly a million people in Luzon and some areas in the capital Manila remained without power for the rest of September 27 and 28.
Among the hardest hit provinces were Isabela and Aurora where most of the population was directly dependent on Agriculture. Out of the total known deaths, most of them were reported to have occurred in and around metropolitan Manila. Santiago Austria, the mayor of Jaén, a 1st class municipality in the province of Nueva Ecija said "We only have four boats but there are so many people waiting to be rescued. Many people here are still on top of their houses. We don't have enough boats to reach them and hand them food." The strong winds that blew through Manila toppled about 40 huge trees around the coastline from where thousands of people were moved from shantytowns into three different school buildings. The number of passengers stranded after Nesat's approach was as high as 4,476 in various ports 28 vessels and 20 motorized bancas were stopped at several ports in Luzon. A spokesman from the Philippine Coast Guard said that the bulk of stranded persons were stuck in ports in Manila, with 3,672; Lucena, 280; and Batangas, 140. By the night of September 28, Nesat's death toll eventually rose to 31. At that time, the first figures of the total estimated damage to agriculture and infrastructure started coming up and was put at 1 billion pesos. The Philippine Department of Health, which is the executive department of the Philippine Government responsible for ensuring access to basic public health services to all Filipinos prepared medical supplies including 2.9 million pesos worth of food and emergency supplies so that they can be distributed among the victims when the flood water recedes.