TS Neoguri Makes Landfall in Kyushu; Continues to Weaken: AIR Analysis

July 11, 2014

According to catastrophe modeling firm AIR Worldwide, Typhoon Neoguri weakened to a tropical storm before it made landfall on Japan’s southernmost island, Kyushu, at 6 a.m. Thursday, July 10, local time (5 p.m. Wednesday, July 9, Eastern Time). Minimum central pressure had risen to 980 mb at landfall and 10-minute sustained wind speeds were 92 km/h [57.1 mph], according to the Japan Meteorological Agency.

“Neoguri was previously forecast to make landfall as a strong Category 2 typhoon, but ultimately arrived on Kyushu as a tropical storm,” said Jason Butke, principal scientist at AIR Worldwide. “Neoguri moved a little more slowly than previously forecast, which allowed for it to interact with the trough to the north and west prior to landfall. The interaction increased vertical wind shear and introduced dry air, cutting off convection on the northern side of the storm. This greatly reduced Neoguri’s impact on Kyushu, where peak 10-minute sustained winds were observed as high as 61 km/h [38 mph] with gusts to 100 km/h [62 mph] in isolated locations, primarily southwest Kyushu. Most locations experienced 36-54 km/h [22.37- 33.5 mph] sustained winds and gusts to 72-90 km/h [44.74-56 mph], or less than tropical storm intensity.”

Butke also noted that with “most of the precipitation and stronger winds occurring to the east and southeast of the storm center, total precipitation across Kyushu prefecture generally ranged from 0-200 mm [7.874 inches], with parts of northern Kyushu receiving no rain and western and southwestern parts receiving the most.

“Kagoshima, a city of 600,000 people located in southwest Kyushu, received 170 mm [6.7 inches] while other populated locations, such as Miyazaki, a city of 400,000 people located in eastern Kyushu, received 55 mm [2.165 inches]. Saga in northwest Kyushu, Fukuoka in north Kyushu, and Oita in northeast Kyushu each received 10 mm [0.394 inches] or less.”

Topography often plays a critical role in precipitation. Ebino, located in southeast Kyushu at 1,150 meters [3,773 feet] of elevation, received 362 mm [14.25 inches], while Kobayashi, 10 km [6.2 miles] to the northeast at 276 meters [905 feet] of elevation, received 159 mm [6.26 inches] and Kakuto, 10 km to the north at 228 meters [748 feet] of elevation, received 92 mm [3.62 inches]. Localized heavy rainfall is common from landfalling tropical cyclones when topography varies considerably over short distances.

Precipitation totals across Shikoku Island prefecture tell a similar story with low-elevation, coastal locations generally receiving less than 100 mm and interior, mountainous locations receiving 100-200 mm [3.94 to 7.87 inches]. Kochi, a city of 350,000 people at 1 meter of elevation located in south central Shikoku Island, received 71 mm [2.8 inches] while Torigatayama at 835 meters [2,739.5 feet] of elevation received 247 mm [9.724 inches].

Neoguri’s rains and winds have caused localized flooding in southern prefectures, at least one mudslide in Nagiso, Nagano prefecture, power outages, and widespread downing of trees. About 100 homes have been reported destroyed or damaged, with another 700 reported flooded.

The Japanese Meteorological Agency has re-issued an emergency warning for landslides and damaging floods for Okinawa, where 6,000 homes were still without power at last report, which is down from more than 100,000 on Tuesday. Naha, the main airport on Okinawa, has re-opened. Airports in Kyushu are open, but flights between Tokyo and Kyushu were canceled.

In preparation for Neoguri traveling up Japan’s coast, plant operators at the Fukushima nuclear power plant began freezing the soil around the plant, making what they call an ice wall to contain contaminated water. They also took the precaution of securing cables, hoses, cranes, and booms around the plant to lessen the chances of the plant’s being damaged by wind-borne debris.

Precipitation in the city of Fukushima was 105 mm [4.134 inches] yesterday, but winds were light and locations along the coast received slightly less precipitation. The warm front has pushed north of Fukushima, so further precipitation will likely be minimal, but isolated heavy precipitation in bands is still possible as Neoguri bypasses to the east.

Butke concluded: “Neoguri is forecast to continue to weaken and slowly accelerate to the east-northeast as sea surface temperatures continue to decrease and vertical wind shear continues to increase. Neoguri should complete extra tropical transitioning in the next 24 hours prior to being absorbed by the approaching extra tropical low.”

Source: AIR Worldwide

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