{"id":66466,"date":"2025-08-16T23:59:00","date_gmt":"2025-08-16T23:59:00","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=66466"},"modified":"2025-08-22T17:08:25","modified_gmt":"2025-08-22T17:08:25","slug":"hurricane-erin-reaches-category-5-intensity-north-of-the-northern-leeward-islands","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/66466","title":{"rendered":"Hurricane Erin reaches Category 5 intensity north of the Leeward Islands"},"content":{"rendered":"

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1-minute GOES-19 Visible and Infrared images with plots of GOES-19 GLM Flash Points, from 1000-1700 UTC on 16 August [click to play MP4 animation]<\/p><\/div>1-minute Mesoscale Domain Sector GOES-19 (GOES-East)<\/em> Visible and Infrared images (above)<\/strong><\/em> showed the WNW motion of the eye of Hurricane Erin<\/strong><\/a> during a 7-hour period as the tropical cyclone rapidly intensified from a Category 4\u00a0 storm at 0950 UTC<\/strong><\/a> to a Category 5<\/strong><\/a> storm at 1520 UTC<\/strong><\/a>, north of the Leeward Islands on 16 August 2025. Erin was the earliest Category 5 hurricane on record in the Atlantic Ocean, as well as one of the Atlantic’s fastest-intensifying tropical cyclones on record (SATCON<\/strong><\/a>). Plots of 1-minute GOES-19 GLM<\/strong><\/a> Flash Points displayed abundant lightning activity within the inner eyewall of Erin’s pinhole eye. In addition, the eye exhibited a notable stadium effect — with a very small low-altitude eye seen in visible imagery, broadening to a larger high-altitude eye in infrared imagery (for example, at 1657 UTC<\/strong><\/a>). The coldest cloud-top infrared brightness temperatures within the eyewall were around -80 C.<\/p>\n

A closer view of 1-minute GOES-19 Visible imagery (below)<\/strong><\/em> revealed the presence of low-altitude mesovortices within the eye. A pinhole eye and mesovortices within the eye are 2 satellite-observed characteristics often associated with intense Category 5 tropical cyclones. In addition, Erin was moving though an environment of weak deep-layer wind shear<\/strong><\/a> and traversing warm sea surface temperatures<\/strong><\/a> — 2 factors that favored intensification.<\/p>\n

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1-minute GOES-19 Visible images, from 1200-1900 UTC on 16 August [click to play MP4 animation]<\/p><\/div>A GOES-19 Visible image at 1424 UTC (below)<\/strong><\/em> included plots of ASCAT ocean surface winds valid at that time; hurricane-force winds only extended about 10-15 miles from the center of Erin. However, significant rainfall contamination within portions of the eyewall adversely affected the quality of a few of the scatterometer winds (with 3 erroneous wind directions seen near the eye).<\/p>\n

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GOES-19 Visible image at 1424 UTC on 16 August, with plots of ASCAT ocean surface winds [click to enlarge]<\/p><\/div>A Synthetic Aperture Radar (SAR) image from RCM-3 at 2229 UTC on 16 August (below)<\/strong><\/em> depicted a peak radial wind velocity of 123 kts in the SE quadrant<\/strong><\/a> of Erin (source<\/strong><\/a>) — this was around the time that the hurricane was undergoing an eyewall replacement cycle, and decreasing in intensity from a Category 5 at 2100 UTC<\/strong><\/a> to a Category 4 at 0000 UTC<\/strong><\/a>.<\/p>\n

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RCM-3 Synthetic Aperture Radar (SAR) image at 2229 UTC on 16 August [click to enlarge]<\/p><\/div>Later that evening, 1-minute GOES-19 Infrared images (below)<\/strong><\/em> showed that the eye of Category 4 Hurricane Erin passed about 40 miles south of Buoy 41043<\/strong><\/a> — which reported hourly wind gusts of 64 kts at 0200 UTC and 0300 UTC on 17 August (the highest 10-minute wind gust was 66.1 kts at 0250 UTC).<\/p>\n

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1-minute GOES-19 Infrared images and GLM Flash Points from 2300 UTC on 16 August to 0500 UTC on 17 August, with hourly plots of weather at Buoy 41043 [click to play MP4 animation]<\/p><\/div>Plots of wind speed \/ wind gusts \/ atmospheric pressure and wave height at Buoy 41043 (below)<\/strong><\/em> indicated that their maximum (or minimum, in terms of pressure) values occurred around 0300 UTC on 17 August (just as the eye of Erin was passing south of the Buoy).<\/p>\n

Plots of wind speed (blue), wind gusts (red) and pressure (green) at Buoy 41043<\/p><\/div>\n

Plot of wave height at Buoy 41043<\/p><\/div>\n

The maximum wave height of 29 ft measured at Buoy 41043 was commensurate with the 25.32 ft significant wave height sensed by Sentinel-3A (and the 39.52 ft sensed by SWOT<\/strong><\/a>) farther to the south, near the northern Leeward Islands, during the morning hours (1237 UTC and 1428 UTC) on 16 August (below)<\/strong><\/em>.<\/p>\n

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Significant wave heights (in feet) in the vicinity of the Leeward Islands on the morning of 16 August, as sensed from Sentnel-3A (brown time stamps, center swath) and SWOT (violet time stamps, eastern swath) [click to enlarge]<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible and Infrared images (above) showed the WNW motion of the eye of Hurricane Erin during a 7-hour period as the tropical cyclone rapidly intensified from a Category 4\u00a0 storm at 0950 UTC to a Category 5 storm at 1520 UTC, north of the Leeward Islands on 16 August […]<\/p>\n","protected":false},"author":18,"featured_media":66472,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[152,76,159,30,8,104,25,2],"tags":[],"class_list":["post-66466","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-altimetry","category-glm","category-goes-19","category-lightning","category-marine-weather","category-sar","category-satellite-winds","category-tropical-cyclones"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/66466","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/users\/18"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/comments?post=66466"}],"version-history":[{"count":54,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/66466\/revisions"}],"predecessor-version":[{"id":66587,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/66466\/revisions\/66587"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/66472"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=66466"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=66466"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=66466"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}