Typhoon Jelawat Batters the Ryuku Islands, heads for Honshu


Typhoon Jelawat Makes a direct hit on Miyakojima with 130mph winds. Western eyewall crosses the island. Japan Meteorological Agency Radar image (September 28th 2012: 11:30pm JST)

Typhoon Jelawat began a weakening stage as it got caught in increasing upper level winds associated with a trough positioned over the Sea of Japan. These winds have distorted the core of the typhoon by allowing dry air to be entrained and by tilting the cyclone vertically where the mid level circulation isn’t perfectly aligned with the surface circulation. These were only small effects because the typhoon was initially so strong. Most of the weakening came from a failed eyewall replacement cycle that made it more vulnerable to these factors. Despite the weakening, Jelwat remained a very strong typhoon and produced damaging winds throughout the Ryuku islands, beginning in Miyakojima. Jelwat packed 130mph winds as it passed only 20miles from Miyakojima, making it a category 4 equivalent storm. Peak gusts reached 106mph and pressures were reported as low as 952.1mb in this region.

Typhoon Jelawat makes landfall/skirts the west coast of Okinawa with 115mph winds as seen on Japan Meteorological Agency Radar (September 29th 2012: 1:00pm JST)

The typhoon continued to weaken, but remained very strong with maximum sustained winds near 115mph making Jelawat a category 3 equivalent storm. The center of Jelawat skirted the west coast of Okinawa and briefly crossed a peninsula near Nago. Baroclinic processes may have enhanced the remnants of the outer eyewall from the failed eyewall replacement cycle. This allowed winds there to reach their peaks in most of southern Okinawa, rather than the right front quadrant of the main eyewall; where the peak winds are typically found.
A JMA observing station reported a peak gust of 137mph in Naha, Okinawa. Additionally, a 128mph gust was reported in Nago, Okinawa. A 132mph gust was observed in Tokashiki, an island to the west of Okinawa that was closer to the core of the typhoon. Pressures bottomed out in Okinawa between 945 and 950mb indicating Jelawat was still a very powerful typhoon. As Jelawat left Okinawa it moved on to Amami where there were multiple reports of gusts between 115 and 120mph.

Reports of damage did come in, including windows and doors blown out of building, some trees and power lines downed, some roof damage, and damage to sheds and barns. An interesting report of cars being flipped and blown around came in as winds were gusting over 115mph.

Jelawat may prove to be the most damaging of the three major typhoons to hit Okinawa as it brought its strongest winds to the most populated regions of the island, whereas the cores of both Bolaven and Sanba passed largely over more rural areas on the northern side of the island.

Plot of peak wind gusts (mph) in the Ryuku Islands as Typhoon Jelawat passed through. The JTWC‘s track of Jelawat is overlaid as a red line. Data sourced from JMA and Wunderground.

The next, and hopefully the last stop for Jelawat is expected to be in Honshu late on the 30th of September JST. The latest forecast track has Jelawat making landfall in Shizuoka prefecture as a typhoon. Nearby prefectures, including Tokyo, will see tropical storm conditions as the typhoon comes ashore. Coastal flooding is possible in areas of onshore winds. Flooding rains with a threat for tornadoes will accompany the strong winds. 


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