{"id":54897,"date":"2023-10-04T23:59:00","date_gmt":"2023-10-04T23:59:00","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=54897"},"modified":"2023-10-07T16:52:08","modified_gmt":"2023-10-07T16:52:08","slug":"typhoon-koinu-reaches-category-4-intensity-as-it-approaches-taiwan","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/54897","title":{"rendered":"Typhoon Koinu reaches Category 4 intensity as it approaches Taiwan"},"content":{"rendered":"
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JMA Himawari-9 Clean Infrared Window (10.4 \u00b5m) images, from 0602 UTC to 2347 UTC [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>\n

Target Sector<\/strong><\/a>\u00a0(2.5-minute interval)\u00a0JMA<\/strong><\/a>\u00a0Himawari-9\u00a0AHI<\/strong><\/a> Clean Infrared Window (10.4 \u00b5m) images (above)<\/strong><\/em> showed Typhoon Koinu after it reached Category 4 intensity at 0600 UTC (SATCON<\/strong><\/a>) on 04 October 2023. The coldest cloud-top infrared brightness temperatures (-80 to -89C, shades of violet to purple) were generally confined to the southern semicircle of the storm. A faster animation (GIF<\/strong><\/a> | MP4<\/strong><\/a>) revealed a bit of trochoidal motion (wobble) to Koinu’s eye.<\/p>\n

Even though Koinu was traversing an area of warmer water (Sea Surface Temperature<\/strong><\/a> | Ocean Heat Content<\/strong><\/a>), it was moving through an environment of increasing deep-layer wind shear<\/strong><\/a> (source<\/strong><\/a>). The general satellite presentation began to deteriorate — with the eye becoming more cloud-filled — as it approached the far southern tip of Taiwan, making landfall around 2332 UTC<\/strong><\/a>.<\/p>\n

Microwave (85 GHz) images from DMSP and GMI satellites (below)<\/strong><\/em> provided 3 views of the evolving eyewall structure at 0934 UTC, 1651 UTC and 2032 UTC.<\/p>\n

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DMSP-17 SSMIS Microwave (85 GHz) image at 0934 UTC [click to enlarge]<\/p><\/div>\n

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GMI Microwave (85 GHz) image at 1651 UTC [click to enlarge]<\/p><\/div>\n

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DMSP-18 SSMIS Microwave (85 GHz) image at 2032 UTC [click to enlarge]<\/p><\/div>\n

A toggle between daytime (0450 UTC) and nighttime (1719 UTC) Suomi-NPP VIIRS Day\/Night Band (0.7 \u00b5m) images (below)<\/strong><\/em> also showed that Koinu’s eye became more cloud-filled during that 12-hour period.<\/p>\n

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Suomi-NPP VIIRS Day\/Night Band (0.7 \u00b5m) images valid at 0450 UTC and 1719 UTC [click to enlarge]<\/p><\/div>\n

It is worth noting that the eye of Koinu passed directly over Orchid Island<\/strong><\/a> around 1334 UTC<\/strong><\/a> — where an unconfirmed wind gust of 213 mph (95.2 m\/s) was measured at the Lanyu Weather Station<\/strong><\/a> within the rear eyewall at 1351 UTC.<\/p>\n\n\n

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Statistics released by CWA confirmed that Lanyu observed a gust of 95.2m\/s in the last hour, and the data was missing after the 10-minute sustained wind speed rose to 47.6m\/s. The current MSLP at Lanyu has dropped to 939hpa, which also broke the historical record? pic.twitter.com\/N7eccj3YP5<\/a><\/p>— Jim yang (@yangyubin1998) October 4, 2023<\/a><\/blockquote>