AIR Tracking Typhoon Kompasu, Tropical Cyclones

According to catastrophe risk modeling firm AIR Worldwide, the sixth, seventh, and eighth named storms of the northwest Pacific season are approaching the Asian mainland bringing high winds and expected heavy rains.

Typhoon Kompasu, the seventh of this year’s tropical cyclones, has slowed its forward motion from about 22 km/h [14 mph] per hour to near 10 km/h [6.25 mph] on Monday. However, as it heads for Okinawa and Korea it has “strengthened considerably and reached typhoon strength Monday afternoon local time,” AIR said. “According to the Japan Meteorological Agency (JMA), as of 9:00 pm Monday (12:00 UTC), Kompasu was roughly 450 kms [282 miles] southeast of Okinawa, Japan, and was moving toward the island at about 12.6 km/h [8 mph].

Kompasu’s maximum sustained winds at that time were not quite 120 km/hr [75 mph], which would classify it as a minimal Category 1 tropical cyclone on the Saffir-Simpson Hurricane Wind Scale. “Its maximum wind gusts, however, were as high as 170 km/h [106 mph], and its radius of tropical storm winds was about 70 kilometers [44 miles],” explained Dr. Peter Sousounis, principal scientist at AIR Worldwide.

“Kompasu is expected to intensify further as it continues to track northwestward along the southern periphery of a deep-layered subtropical ridge that currently is anchored south of Japan—and to peak at about 170 km/h [106 mph] shortly after it passes over Okinawa,” he added.

“By Wednesday morning Typhoon Kompasu is expected to curve into the Yellow Sea between the China mainland and the Korean peninsula,” Sousounis continued. “However, because of increased vertical wind shear in the area—associated with a westerly-flowing subtropical jet stream in the region and the relatively cooler temperatures of the Sea—Kompasu is expected to weaken before it makes landfall near Inchon, South Korea, probably sometime Thursday evening, September 2nd. Over the rugged mountains of the Korean peninsula Kompasu will undergo extra tropical transition as it exits into the Sea of Japan, moving toward Hokkaido, Japan.”

About 1,500 kilometers farther west and south, roughly 300 kms. [188 miles] east of Hong Kong and 450 kms [281 miles] west and south of the southern coast of Taiwan—Tropical Cyclone Lionrock has been tracking north and east toward Taiwan at about 5 kms. [3.1 mph] per hour for the past day. As of the 9:00 pm JMA advisory, Lionrock had maximum sustained winds of about 105 km/h [66 mph], with gusts up to 150 km/h [94 mph], placing it as a strong tropical storm on the Saffir-Simpson Hurricane Wind Scale.

Lionrock’s radius of maximum winds was about 100 kms [60 miles], and maximum significant wave height is about five meters [16 feet]. How Lionrock will interact with weather conditions ahead of its present track, however, remains uncertain, and forecasters report only marginal confidence in current projections.

Over the weekend, another tropical cyclone, Namtheun, formed to the north and east of Taiwan. Currently only about 60 kms [37.5 miles] north of Taipei, it has maximum sustained winds of about 30 km/h [18.75 mph], gusts of 40 km/h [25 mph], and a radius of maximum winds of about 45 kms [28 miles]. Forecasters expect Namtheum to intensify further and track toward the southwest, eventually to become absorbed by Lionrock sometime late Wednesday or the morning of Thursday, local time.

The Central Weather Bureau in Taipei is expecting that the outer bands of the systems will bring torrential rain across the island and strong winds to coastal cities. The Bureau has issued a torrential rain warning and said that from midnight to 8:00 am local time Monday rain accumulation had already reached 12.2 centimeters [4.8 inches] in some places around the capital city of Taipei.

Expectations on the mainland are similar, and Chinese officials expect downpours across the east coast of Guangdong and the coastal region of western Fujian Province, further exacerbating the flood conditions China has suffered for the past month and more. Both provinces have initiated emergency response plans to monitor the storms’ development and provide early warnings.

AIR said it is “is continuing to monitor all developments in the northwest Pacific basin and will provide updates as warranted by events.”

Source: AIR Worldwide