Typhoon Lan
10/23/2017 1:30:00 PM
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Landfall 10/23/2017 1:30:00 PM 
Posting Date: 10/23/2017 1:30:00 PM

Typhoon Lan made landfall as a Category 2-equivalent storm on the Saffir-Simpson Scale at Shizuoka at 3 a.m. on Monday, October 23 local time (18:00 UTC on Sunday, October 22) just 175 km (108 miles)southwest of Tokyo. At landfall, Lan had maximum sustained winds of 161 km/h (100 mph) and a minimum central pressure of 950 mb. It crossed Honshu, Japan’s main island, impacting Tokyo on its way to the Pacific coast of Tohoku and was then downgraded to an extratropical cyclone about 12 hours after landfall while it was still east of Hokkaido.

Meteorological Summary

Lan started intensifying quickly over warm waters on October 19, bypassed the Philippines, then achieved sustained wind speeds of at least 150 mph (241 km/h) two days later, qualifying it as a Super Typhoon as it headed toward Okinawa/Tokyo, Japan. The storm then weakened to a Category 2 storm before making landfall.

Reported Impacts

Because of Lan’s large size, the storm’s impacts were felt in areas far from the center. Across both Shikoku and Honshu islands, rainfall ranging between 125 and 250 mm was forecast, with some locally heavy rainfall expected to be upwards of 500 mm in some areas. Since Friday Owase has reported 630 mm of rain (more than half of which fell on Sunday) and Cape Shionomisaki, the most southerly point of the main island of Honshu, reported 321 mm of rain fell; both cities are on the Kii Peninsula. Tokyo and Osaka escaped the heaviest rains—counter to the expectations of forecasters—with 162 mm and 169 mm falling during last weekend, respectively.

Many municipalities ordered evacuations, including Koriyama, a city 200 km north of Tokyo, where 80,000 people were ordered to evacuate because a river there was expected to overtop its banks. More than 380,000 were ordered to evacuate on Sunday, and some of these orders are still in effect.  Flooding in western Japan caused by the storm has inundated hundreds of homes.

Heavy winds and huge waves were reported. Roughly 500 flights were canceled on Sunday and 350 more today, including those by Japan Airlines and All Nippon Airways. Crown Prince Naruhito had his flight to Kochi Prefecture from Tokyo’s Haneda airport canceled. Passenger trains lost power and became stuck on Sunday into Monday, and on Monday morning express train service—including the Tokaido Shikansen Line between Tokyo and Osaka—and ferry services were canceled. In addition, Toyota suspended operations on Monday at its vehicle factories in the prefectures of Iwate, Miyagi, Gifu, Shizuoka, Aichi, Mie, and Fukuoka.

Japan still held its national elections during this past weekend, but regional ballot-counting was delayed for a time.

Exposure at Risk

Japan has strict and well-enforced construction codes, although many existing structures predate the existence of these codes. Residential exposures are dominated by wood construction; non-wood residences primarily consist of steel and concrete. Modern wood construction typically demonstrates the best performance in typhoons among all wood constructions. However, damage to roof coverings and windows can allow wind-driven rain to enter and cause extensive damage to contents. Furthermore, dislodged external components can become wind-borne debris and cause damage to surrounding structures and glazing.

Larger multi-family apartment buildings and commercial and industrial structures are generally engineered and made of reinforced concrete or steel. Complete structural collapse of engineered buildings due to typhoons is extremely rare; damage is usually confined to nonstructural components, such as mechanical equipment, roofing, cladding, and windows.

A significant portion of industrial stock is of non-engineered light metal construction, which is one of the construction types most vulnerable to high winds. Low-rise, non-engineered commercial and industrial buildings usually perform similarly to single-family homes under typhoon conditions.

Even with modern flood-control structures, the risk of flood damage remains high in Japan. For a given flood depth/effective surge depth, a residential wood frame building generally will sustain more damage than a residential masonry building. Concrete construction is less vulnerable to flood than steel or masonry. Commercial and apartment buildings usually have stronger foundations than residential buildings, and are thus better able to resist flood loads. Water damage to machinery and contents drives most flood-related loss; also, because damage is usually limited to the lower stories of a building, high-rise buildings will experience a lower damage ratio than low-rise buildings because a smaller proportion of the building is affected.

Forecast Track and Intensity

Lan was downgraded to an extratropical storm 12 hours after landfall and after it had cleared Honshu Island and was east of Hokkaido; it is expected to dissipate further today.

Typhoon Lan
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