Typhoon Roke

Post Landfall 1 | Summary
Posting Date: September 21, 2011, 1:00:00 PM

After crossing over more than 350 kilometers of the main Japanese island of Honshu, Typhoon Roke, the 15th named storm of the 2011 Northwest Pacific typhoon season, has moved out to sea and is currently headed toward the Kuril Islands, northeast of Hokkaido. Roke passed to the west of Tokyo early yesterday evening local time. Current Conditions As of the Japan Meteorological Agency’s (JMA) 14:00 UTC analysis today (11:00 pm local time), Typhoon Roke had maximum sustained winds of 150 km/h with gusts up to 213 km/h. Roke’s center was located over the ocean about 220 km northeast of Fukushima, the city that was damaged so severely by the Tohoku tsunami and earthquake in March of this year. Roke’s tropical storm force winds extend outward about 70 km to the northwest and 190 km to the southeast. The storm is currently moving to the northeast at about 68 km/h. Roke made landfall about 250 kilometers southwest of Tokyo in Shizuoka Prefecture near Hamamatsu City at about 2:00 pm local time (05:00 UTC). Roke had intensified rapidly from a Category 1 typhoon to a Category 3 typhoon during its approach to Japan, but it weakened before making landfall. Roke came ashore with winds of about 180 kilometers per hour—a borderline Category 2/Category 3 storm—and moved to the northeast (toward Tokyo) at about 46 km/h. Weakening after landfall, Roke’s winds during most of the storm’s passage across Honshu were at about 150 km/h. Exposure at Risk Minimal structural damage from wind is expected given Roke’s wind speeds over land. In the countryside, wood frame homes dominate residential construction. Many have heavy, clay tile roofs meant to prevent damage from wind. At Roke’s wind speeds, these buildings are expected to have minor roof damage and little or no structural damage. Larger multi-family apartment buildings, as well as commercial and industrial structures, are generally engineered and made of reinforced concrete or steel, making them less vulnerable to Roke’s winds. They would be expected to experience minor damage to roofs and sidings, with minor to moderate damage to decorative elements and signage. Modern urban structures are similarly expected to withstand Roke's wind speeds with minimal damage; Japan has strict and well-enforced construction codes. Thus, the chief impact from Roke is expected to be flood damage and the effects of flood, such as mudslides. Flood damage in Japan is not automatically included in wind policies. In typical Japanese flood policy coverage, a specified payout is made only when actual damage falls within a specified range of loss. The vulnerability of buildings to flood damage varies by construction type. For a given flood depth, a residential wood-frame building is expected to 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. Building height also affects flood damage. Because damage is usually limited to the lower stories of a building, high-rise buildings will experience a lower damage ratio—the repair cost compared to the total replacement value of the building—than low-rise buildings because a smaller proportion of the building is affected. Reported Impacts Typhoon Roke’s heavy rains and accompanying flooding have caused extensive evacuations, widespread transportation disruptions, and power outages. As many as six people so far have been reported killed or missing. As much as 80 millimeters of rain per hour (3.1 inches) has fallen in central Honshu, and JMA has issued warnings for landslides and flooding throughout the island. Over the last three days, total precipitation amounts have exceeded 400 mm at about a dozen monitoring stations; Tokushima Prefecture, which is southwest of where Roke made landfall on Honshu, has reported an accumulation of 600 mm. According to local Aichi prefecture authorities, heavy rains have already caused floods and road damage in dozens of locations in Nagoya—about 270 kilometers west of Tokyo—and several other cities. They report that parts of Nagoya were flooded in areas near swollen rivers, and rescue workers have been helping residents evacuate in rubber boats. Commuter trains were suspended in Tokyo, and tens of thousands of commuters trying to rush home became stuck at train stations all across the sprawling city. By late evening, fire department officials had reported that three people had been injured in the city. The Tokyo Electric Power Company has reported that more than 575,500 households have lost power, and the Chubu and Kansai Electric Power Companies have also reported power outages. About 450 flights have been cancelled and Central Japan Railways has suspended train service. Toyota Motor Corporation suspended Wednesday’s afternoon shift at 11 factories in Aichi prefecture, and Honda Motor Company said it also was changing the day’s working hours at its Hamamatsu factory; Mitsubishi Motors Corporation and Suzuki Motor Corporation, however, say they are operating as normal and do not plan to shut any of their factories. The JX Nippon Oil & Energy Corporation stopped berthing operations at six refineries, but refining operations and truck shipments have been operating as usual. Although the straight-on passage of Typhoon Roke over the stricken Fukushima Dai-Ichi reactor buildings that had been expected from pre-landfall projections did not actually happen, the decontamination operations in progress there were suspended all the same for safety reasons. Forecast Track and Intensity At present, according to the Joint Typhoon Warning Center (JTWC), the circular movement of Roke’s winds—its deep convection—is weakening rapidly. Most of the deep convection is now in Roke’s northeast quadrant. The JTWC expects Roke to undergo extra-tropical transition over the next twelve hours as it tracks northeastward rapidly, and thereafter for the storm to dissipate, although there remains a slight chance it could regenerate. The AIR Tropical Cyclone team is analyzing the latest meteorological and track data concerning Typhoon Roke and has begun simulating the storm using the AIR Northwest Pacific Basinwide Typhoon Model. If modeled losses are significant, ALERT subscribers will be notified of the results when they become available.

Post Landfall 1 | Downloads
Posting Date: September 21, 2011, 1:00:00 PM