Tag Archives: super typhoon

The 2015 Northwest Pacific Typhoon Season: Already a Record-Breaker

While the Atlantic hurricane season is expected to be below average this year, the North Pacific is smashing records. Fuelled by the strengthening El Niño conditions, the Accumulated Cyclone Energy (ACE)—used to determine how active a season is by measuring the number of storms, their duration and their intensity—continues to set unprecedented highs for the 2015 season.  According to Dr. Philip Klotzbach, a meteorologist at Colorado State University, the North Pacific ACE is 30% higher for this time of year than at any other time since 1971.

Philip J. Klotzbach, Colorado State University

To date, there have been 12 named Northwest Pacific storms, of which three have strengthened to Category 5 super-typhoon status, and two have strengthened to Category 4 typhoon. Typhoon Maysak was the first of the super-typhoons to develop and is reportedly the strongest known storm to develop so early in the season—it eventually passed over the northern Philippines in late March as a tropical depression. Super-Typhoons Noul and Dolphin followed in quick succession in May, with Noul scraping the northern tip of the Philippines, and Dolphin tracking directly in-between the islands of Guam and Rota.

China is recuperating after getting hit by Typhoons Linfa and Chan-Hom only days apart. Linfa made landfall on July 9, bringing strong winds and heavy rainfall to Hong Kong and southern China’s Guangdong province. Two days later, Chan-Hom brought tropical storm-force winds and heavy rainfall to Taiwan and the Japanese Ryukyu Islands before briefly making landfall as a weak Category 2 storm over the island of Zhujiajian in the Zhejiang province. Prior to landfall, Chan-Hom was anticipated to pass over Shanghai, but swung northeast and missed China’s largest city by 95 miles. Despite this near-miss, Chan-Hom still stands as one of the strongest typhoon to have passed within 100 miles of the city in the past 35 years.

Typhoon Nangka, the first typhoon to hit Japan this season, intensified to a Category 4 storm before ultimately making landfall as a Category 1 storm over the Kochi Prefecture on Shikoku Island, Japan. Although Nangka’s strength at landfall was weaker than originally forecast, the high level of moisture within the system caused significant rainfall accumulations, leading to widespread flooding and the threat of landslides. While there was an initial fear of storm surge in Osaka Bay, there has been limited damage reported.

This record-breaking season has been strongly influenced by the strengthening El Niño conditions, which can be characterised by several physical factors including warmer sea surface temperatures, a higher number of Category 3-5 typhoons, and a greater proportion of typhoons that follow recurring or northward tracks—all of which have been evident so far this year.

With El Niño conditions expected to continue intensifying the storms to come, this season highlights the necessity for a basin-wide multi-peril model, connected through an event-based approach and correlated geographically through a basin-wide track set. These will be featured in the new Japan typhoon model, due out next year, followed by the South Korea and Taiwan typhoon models. The RMS China typhoon models currently models typhoon wind, inland flood and surge for a correlated view of risk.

As El Niño conditions continue to bolster the Northwest Pacific typhoon season, RMS will be monitoring the situation closely. In September, RMS will be releasing a white paper on ENSO in the West Pacific that will provide further insight into its affects.

What’s at risk as Super Typhoon Hagupit approaches the central Philippines?

Only thirteen months since Super Typhoon Haiyan devastated parts of the Philippines, the region is again under threat from a large typhoon. Typhoon Hagupit, locally referred to as Typhoon Ruby, is currently Category 4 strength and expected to make landfall over the weekend.

Hagupit isn’t forecast to be as strong as Typhoon Haiyan; however, its projected path takes it across southern Luzon Island, as well as an area 35 miles south of the Central Capitol Region that has a high concentration of exposure at risk of substantial wind damage.

As the typhoon makes landfall, there is also the potential for storm surge along low-lying coastal areas, which are characterized by complex coastlines and bays.

At this stage,there still remains a large degree of uncertainty surrounding Hagupit’s forecast track, intensity, and landfall locations, which the RMS catastrophe response team is monitoring closely.

High concentrations of exposure at risk

The Central Capitol Region includes Quezon City, the largest city in the Philippines, as well as Manila, which is the second largest city and serves as the capitol. This region has the highest concentration of economic insurable exposure ($165.5 billion), which accounts for approximately 20 percent of the country’s total insurable exposure. Using the RMS Economic Exposure datasets, we can see that $91 billion is residential, $59 billion commercial, and $14.4 billion is industrial exposure. Quezon City has the highest value of insurable exposure with $32.3 billion, of which 65 percent is commercial.

In addition, our Industrial Clusters Catalog shows that a high proportion of industrial clusters could be impacted by Hagupit. These are located in the surrounding districts of Rizal and Laguna within the Calabarzon region, as well as the Lima Technology Center, which is in the direct path of typhoon.

Despite being forecast to making landfall further north than Typhoon Haiyan, Hagupit is still likely to affect areas that are still recovering from the impacts of Typhoon Haiyan.

Lessons from Typhoon Haiyan Reconnaissance

Typhoon Haiyan illustrated that the complex geometry and shallow water where Haiyan made landfall can give rise to significant storm surge heights, evidenced by high surge levels experienced in San Pedro and San Pablo Bays, affecting Tacloban City. The Philippines is characterized by these complex coastlines and shallow waters, and future typhoon events, including Typhoon Hagupit, could similarly cause significant storm surge in other areas of the Philippines.

In the aftermath of Typhoon Haiyan, our scientists conducted extensive field reconnaissance work. They observed that buildings were structurally more resilient to typhoon winds because of the region’s high risk of earthquakes. There is abundant use of reinforced concrete frames, which ensures the structural integrity of the buildings for earthquakes and winds.

Wind alone did not cause substantial structural damage to structures built with reinforced concrete; however, the severe storm surge flooding caused the failure of some reinforced concrete framed buildings. Instead, wind damage was most evident to the roofing of buildings, particularly light aluminum roofs. Large span commercial and industrial light metal roofs collapsed, but concrete roof tiles preformed better.

Since Haiyan, the Filipino government has been actively discussing sponsoring a catastrophe bond with the World Bank, but the process is complex and will take time to develop.