Super typhoon Nepartak to hit Taiwan with violent winds, drench China

Typhoon Nepartak, the first storm of the north-western Pacific tropical cyclone season after a record 199 day lull, has intensified strongly into a category 5 equivalent storm. Super typhoon Nepartak is heading directly for Taiwan and is expected to strike it with damaging, violent winds.

Super typhoon Nepartak is estimated to have sustained winds of around 170mph and is gusting to an estimated 205mph, strong enough to cause considerable damage for sure. Moving west north-west at around 16mph, super typhoon Nepartak is expected to strike Taiwan during the next 12 to 24 hours.

Super typhoon Nepartak forecast track or path towards Taiwan - Source: Weather Underground

Taiwan is less populated to the southern edge, where typhoon Nepartak’s winds will be most severe, but forecasters are expecting some wind damage over the northern edge where much greater concentrations of property and lives are to be found.

Aon Benfield’s Impact Forecasting warns of a medium to high significant local insurance loss potential due to super typhoon Nepartak. With Taiwan having reasonable insurance penetration there is always the chance of some impact to reinsurance contracts, particularly if the storm can maintain intensity as it crosses the high mountains of Taiwan.

Nepartak will cross the center of Taiwan, weakening as it goes, before emerging back over the sea in the straits of Taiwan where there is a chance of some re-intensification before it hits mainland China.

Forecasts suggest rainfall totals of 150-300mm are expected along the track of super typhoon Nepartak, reducing to 100-200mm as it traverses China. Shanghai has moved a little further from the track for Nepartak, although there is some forecast uncertainty regarding how much the typhoon will curve, but the storm should be greatly weakened by the time it reaches that area.

Insurance, reinsurance and ILS interests should continue to monitor super typhoon Nepartak closely, as it’s now clear that Taiwan is in the bull’s eye and will take a damaging hit from the storm.

ILS and collateralised reinsurance interests have been shown to be exposed to Taiwan typhoon risks before, due to the proliferation of private ILS and reinsurance deals. However the traditional reinsurance market will hold most of the exposure in this region of the world.

You can view a near real-time visualisation of typhoon Nepartak on approach to Taiwan below. Drag the wind speed indicator to analyse the strength of the storm.

The latest update from Impact Forecasting can be found below.

LATEST DETAILS ON SUPER TYPHOON NEPARTAK

COORDINATES: 21.3° north, 124.3° east (previous location: 19.1° north, 129.4° east)
LOCATION: 510 kilometers (315 miles) southeast of Taipei, Taiwan
MOVEMENT: west-northwest at 26 kph (16 mph) (previous: west-northwest at 33 kph (21 mph))
WINDS: 280 kph (175 mph) with gusts to 335 kph (205 mph) (previous: 260 kph (160 mph))
RADIUS OF TROPICAL STORM-FORCE WINDS: 300 kilometers (185 miles)
RADIUS OF HURRICANE-FORCE WINDS: 75 kilometers (45 miles)
MINIMUM CENTRAL PRESSURE: 911 millibars (previous: 918 millibars)
SAFFIR-SIMPSON SCALE RANKING*: Category 5

LANDFALL AND LOSS PROBABILITIES

24-HOUR LANDFALL POTENTIAL: HIGH
24-HOUR SIGNIFICANT LOCAL INSURED LOSS POTENTIAL: MEDIUM-HIGH

DISCUSSION

Super Typhoon Nepartak, located approximately 510 kilometers (315 miles) southeast of Taipei, Taiwan, is currently tracking west-northwest at 26 kph (16 mph). Animated satellite imagery shows a tightly wound cyclone with a well-defined eye feature which lends high confidence to the initial position. Convective banding has reformed over the last six hours on the northern and southern peripheries of the system as observed on local radar imagery as well as satellite imagery. The current intensity is assessed at 280 kph (175 mph) and is based on current Dvorak intensity estimates from all agencies that report to the JTWC. Super Typhoon Nepartak has maintained its intensity over the past six hours, partly due to the recent development of deep convective bands feeding into the system as well as good outflow aloft and very warm sea surface temperatures.

Nepartak will continue tracking generally west-northwestward along the periphery of a ridge of high pressure located to the northeast until it makes landfall over central Taiwan in the next 12 to 24 hours. The system will then weaken considerably beyond 24 hours due to land interaction then reorganize somewhat over the Taiwan Strait making landfall again over China sometime between 36 and 48 hours from now.

Further ahead in the forecast period, Super Typhoon Nepartak will continue tracking over land rounding the axis of the high pressure ridge, turning north, until it dissipates by Sunday morning (local time). Forecast models differ regarding the speed and tightness of the poleward turn once the system is over land but show tight grouping in the track making landfall over Taiwan and China lending high confidence to the JTWC forecast track.

The latest update from risk modelling firm AIR Worldwide can be found below.

Typhoon Nepartak Threatens Taiwan: AIR

BOSTON, July 6, 2016 – According to catastrophe modeling firm AIR Worldwide, over the weekend, Nepartak formed to the south of Guam and strengthened to typhoon status on Monday as the first named storm in the western North Pacific basin since mid-December 2015, setting a new record for the longest period (200 days) without tropical storm in the basin in 66 years.

“In just 48 hours, Nepartak rapidly intensified from a tropical storm to a typhoon with maximum sustained winds of 216 km/h (134 mph)—equivalent to a Category 4 hurricane on the Saffir-Simpson scale—and a minimum central pressure of 900 mb,” said Christopher Bednarczyk, scientist at AIR Worldwide. “It is currently located at 20.1°N, 127.0°E, to the southeast of Taiwan, in an area of high ocean heat content and low vertical wind shear, which has contributed to its rapid intensification. Satellite imagery shows a clearly defined eye and good upper-level outflow. It is expected to make landfall early Friday before turning northward toward eastern China.”

Bednarczyk continued, “The Northwest Pacific Basin produces more tropical cyclones each year than anywhere else in the world. On average, this basin spawns 29 tropical cyclones each year—20 of which reach typhoon status. This high frequency can be primarily attributed to the extremely large expanse of very warm water in the basin. In Southeast Asia (i.e., Guam, Hong Kong, Macau, the Philippines, Saipan, Taiwan, and Vietnam), Taiwan experiences the third-highest number of landfalling tropical cyclones annually—two per year on average—after the Philippines (first) and Vietnam (second).”

“Nepartak is forecast to continue intensification, potentially reaching the equivalent of a Category 5 hurricane. However, it is moving into an environment with cooler ocean temperatures than its current location, which is projected to contribute to weakening prior to landfall. Model consensus continues to point to a Taiwan landfall early Friday in Hualien or Taitung County. Nepartak is projected to bring torrential rains to Taiwan, with 100 mm of rainfall anticipated. Significant storm surge is also projected, as waves of up to 13 meters have already been reported at sea.”

Inland penetration will be mitigated by the steep elevation along the island’s east coast. Flooding, landslides, wind-borne debris, coastal flooding, and damage or interruption to infrastructure (power, transportation systems, etc.) is expected.

Movement over the mountainous terrain of Taiwan will weaken the storm before it has a chance to turn northward and make a potential second landfall in eastern China on Saturday. There still exists considerable uncertainty in the location and intensity of the possible impact to China.

Typhoon warnings have been issued for counties on the eastern side of Taiwan. An emergency center is set to be operational beginning Wednesday evening according to a spokesperson from the Taiwan Central Emergency Operation Center. Food prices in Taiwan have already begun to soar as people have started their own emergency preparations.

According to AIR, while high winds typically cause the most tropical cyclone damage in other parts of the world, rain-induced flooding often causes the most damage in the Northwest Pacific Basin. Because tropical cyclones typically weaken rapidly upon interaction with the central mountain range in Taiwan and the eastern coast of the island is relatively unpopulated, heavy wind losses tend to be restricted to the east coast of Taiwan, including the areas of Taitung and Hualien. Strictly enforced building codes throughout the nation have resulted in structures with generally good wind resistance.

The country faces a serious threat from flooding, which is greatest along the southwestern mountains due to orographic lifting combined with occasional South China Sea monsoon-scale influences. The heavily urbanized areas of Taipei and Kaohsiung have sustained heavy flood damage during typhoons in the past, including the Tyhpoons Nari (2001) and Morakot (2009), both of which produced unprecedented levels of flooding.

According to AIR, damage to property in Taiwan is generally distributed equally between wind and flood, but storm surge also has some appreciable contributions. Storm surge is significant in the west coast of Taiwan, and could heavily affect Taipei area and Kaohsiung area through Tamsui River and Love River. The deep bathymetry of the east coast minimizes storm surge risk on that side of the island.

Residential take-up rates in Taiwan are low and commercial take-up rates vary. The population density along the eastern coast—the region most vulnerable to flood—is quite high. Such high concentrations of people increase the risk of loss of life and destruction of property. Industry impacts will depend on the direction and intensity of Hurricane Nepartak at landfall, as well as duration post-landfall.