An unusual December super-typhoon made several landfalls
in the Philippines on Christmas Day 2016, bringing heavy rainfall, fierce wind
gusts, and dangerous flooding to the island nation. While the number of fatalities associated
with Super-Typhoon Nock-Ten—or Nina, as the storm has become to be known in the
Philippines—remains relatively low, the physical damages are currently
estimated to be in excess of USD 100 million.
Treacherous typhoons are not an uncommon threat to the
Philippines, which are located in the Western Pacific Ocean. In fact, in 2016, the region was ravaged by
several powerful super-typhoons, equal to Category-5 hurricanes in the Atlantic
basin. For example, super-typhoon Haima—or, Lawin, as it is known in the Philippines— reached maximum
sustained wind speeds in excess of 160 mph.
Haima made landfall in the Philippines on October 19, 2016, causing
damages of approximately USD 150 million.
However, what distinguished Super-Typhoon Nock-Ten is the
speed of its formation, its subsequent rapid intensification, and, in
particular, its late timing. In fact, because
of these factors Nock-Ten has been awarded the status of “strongest tropical cyclone to be recorded worldwide on Christmas Day in over half a century.”
The record-breaking storm developed extremely rapidly,
reaching maximum sustained winds of 160 mph within a short timeframe of five
days. On December 20, 2016,
meteorologists detected a tropical disturbance near Yap in the Western Pacific
Ocean, over 1,100 miles east of the Philippines. By December 23, 2016, the tropical
disturbance had intensified to a typhoon, with maximum sustained winds of 115
mph, the equivalent of Category-4 hurricane in the Atlantic basin. Benefiting from ideal conditions along its
path with a low vertical wind shear and warm ocean waters, Nock-Ten then
swiftly transformed into a super-typhoon by Christmas Day, with wind speeds equivalent
to a Category-5 hurricane.
Even though tropical cyclones can form in the Western Pacific
region all year round, it is unusual for a typhoon of this strength to form
late in December. Typhoons, like
hurricanes, require ideal conditions, including surface water temperatures of
at least 26.5 degrees Celsius, to form and strengthen. With cooler sea surface temperatures in the
Northern Hemisphere during the winter months, tropical cyclones in the Atlantic
and Western Pacific become less likely.
In fact, according to the government weather agency of the Philippines,
only seven typhoons struck the country on Christmas Day in the past 65 years.
Similarly, in the Atlantic basin, hurricane formation
generally peaks in August and September, before dropping sharply in October and
November as water temperatures fall.
However, late-season hurricanes do occur occasionally, with devastating effects. For instance, Hurricane Wilma formed on
October 16, 2005 and made landfall in Southern Florida on October 24,
2005. Over sixty people died in the
United States alone in accidents related to this powerful Category-5 cyclone,
and damage to property exceeded USD 20 billion.
Unusual late-season tropical cyclones, such as
Super-Typhoon Nock-Ten or Hurricane Wilma, may pose serious concerns for the insurance
industry. Catastrophe models, which are nowadays regularly used in the industry to assess the
probability of the occurrence of catastrophic events, depend, inter alia, on historic data. Where the data is of poor quality or
unavailable, it may be difficult to generate reliable models to accurately
predict late-season tropical cyclones.
Certain developing regions or countries that are prone to tropical
cyclones may not have the tools to adequately record and analyze the data
associated with late-season tropical cyclones.
In addition, catastrophe models depend on the correct
analysis of the data that is fed into them.
For example, with regard to late-season cyclones, the question may arise
to what extent global warming and rising water temperatures contribute to their
formation, if at all? Do other factors,
such as, for instance, changes in the atmosphere, explain the strength of
recent late-season cyclones? That is to
say, is Super-Typhoon Nock-Ten the proverbial “odd one out” or is it the
harbinger of larger changes?
Lastly, late-season tropical cyclones may impact certain
lines of business in the insurance industry more than others. For example, the impending threat of Hurricane Wilma in late October 2005 forced the PGA Tour to cancel the Miccosukee Championship in Miami for safety reasons. Several other sporting events were eventually
postponed or rescheduled, causing quite a headache to event organizers and
attendees alike. Likewise, Super-Typhoon
Nock-Ten impacted Christmas celebrations throughout the Philippines and left thousands of travelers stranded.
In sum, the more data on late-season cyclones is
recorded and analyzed, the better the insurance industry is equipped to understand
these phenomena and their causes and to brace for the future.
Posted by Isabella Stankowski-Booker