{"id":29062,"date":"2018-07-22T23:59:27","date_gmt":"2018-07-22T23:59:27","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=29062"},"modified":"2018-07-24T23:02:18","modified_gmt":"2018-07-24T23:02:18","slug":"cloud-top-warm-trench-infrared-signature-over-colorado","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/29062","title":{"rendered":"Cloud-top “warm trench” infrared signature over Colorado"},"content":{"rendered":"

\"GOES-16<\/a>

GOES-16 “Clean” Infrared Window (10.3 \u00b5m)<\/em> images, with plots of surface reports [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>GOES-16 “Clean” Infrared Window (10.3 \u00b5m<\/strong><\/a>) images (above)<\/strong><\/em> revealed a well-defined “warm trench” signature (ring of brighter red enhancement)<\/em> surrounding the cold overshooting top (cluster of pixels enhanced as black to lighter shades of gray)<\/em> of a thunderstorm in far eastern Colorado during the nighttime hours on 22 July 2018<\/strong><\/a>. This warm trench appears to be a ring of compensating subsidence immediately surrounding the vigorous overshooting top; the cold\/warm (overshooting_top\/warm_trench)<\/em> “delta-T” on the 0412 UTC image<\/strong><\/a> was 16.4\u00baC (-85.5\u00baC \/ -67.1\u00baC). Just to the south, at 0453 UTC there was a northerly peak wind gust to 45 knots or 52 mph at KITR (Burlington Colorado: plot<\/strong><\/a> | text<\/strong><\/a>) as the updraft supporting the overshooting top collapsed — but no other SPC storm reports<\/strong><\/a> were seen in that area.<\/p>\n

A 250-meter resolution Terra MODIS Infrared Window (11.0 \u00b5m) imageat 0402 UTC (below)<\/strong><\/em> with a slightly different color enhancement showed similar delta-T values (-81\u00baC\/-67\u00baC) with the overshooting top \/ warm trench. The diameter of the warm trench was approximately 30-40 miles.<\/p>\n

\"Terra<\/a>

Terra MODIS Infrared Window (11.0 \u00b5m)<\/em> image, with plots of surface reports [click to enlarge]<\/p><\/div>A plot of 00 UTC rawinsonde data from North Platte, Nebraska (below)<\/strong><\/em> showed a tropopause temperature of -73\u00baC at an altitude of 15.7 km or 51,500 feet — so the much colder infrared brightness temperatures seen on GOES and MODIS imagery were indicative of a very robust overshooting top that penetrated the tropopause a significant distance.<\/p>\n

\"Plot<\/a>

Plot of 00 UTC rawinsonde data from North Platte, Nebraska [click to enlarge]<\/p><\/div>The GOES-16 Cloud Top Height product at 0412 UTC (below)<\/strong><\/em> indicated values of 54,000 ft \/ 49,000 ft for the cold overshooting top \/ warm trench features — however, note that the resolution of this infrared-derived<\/strong><\/a> product is 10 km (and the accuracy is within 1500 feet).<\/p>\n

\"GOES-16<\/a>

GOES-16 Cloud Top Height derived product at 0412 UTC [click to enlarge]<\/p><\/div>Another interesting (and yet-to-be-explained) feature was an arc of warming<\/em> cloud-top infrared brightness temperatures that was seen propagating southwestward toward the overshooting top \/ warm trench signature. A larger-scale view (below)<\/strong> <\/em>showed this wave feature moving from southwestern Nebraska at around 02 UTC to southern Colorado\/Kansas by 10 UTC.<\/p>\n

\"GOES-16<\/a>

GOES-16 “Clean” Infrared Window (10.3 \u00b5m)<\/em> images, with 11.2 \u00b5m infrared Derived Motion Winds [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>This cloud-top wave feature was also apparent on GOES-16 Upper-level Water Vapor (6.2 \u00b5m<\/strong><\/a>) images (below)<\/strong><\/em> — at times the wave was tracked by Derived Motion Winds at speeds of 20-30 knots (0252 UTC<\/strong><\/a> | 0337 UTC<\/strong><\/a> | 0922 UTC<\/strong><\/a>). According to rawinsonde data from Dodge City, Kansas (plot<\/strong><\/a> | data<\/strong><\/a>) as well as North Platte, winds with a northerly to easterly component were only found at altitudes of 20 km or higher!<\/p>\n

\"GOES-16<\/a>

GOES-16 Upper-level Water Vapor (6.2 \u00b5m)<\/em> images, with 6.2 \u00b5m water vapor Derived Motion Winds [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>Special thanks to NWS Grand Rapids<\/strong><\/a> forecasters Brett Borchardt and TJ Turnage for bringing this case to our attention!<\/p>\n","protected":false},"excerpt":{"rendered":"

GOES-16 “Clean” Infrared Window (10.3 \u00b5m) images (above) revealed a well-defined “warm trench” signature (ring of brighter red enhancement) surrounding the cold overshooting top (cluster of pixels enhanced as black to lighter shades of gray) of a thunderstorm in far eastern Colorado during the nighttime hours on 22 July 2018. This warm trench appears to […]<\/p>\n","protected":false},"author":18,"featured_media":29076,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[74,12,25,71],"tags":[],"class_list":["post-29062","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-goes-16","category-modis","category-satellite-winds","category-terra"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/29062","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=29062"}],"version-history":[{"count":26,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/29062\/revisions"}],"predecessor-version":[{"id":29101,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/29062\/revisions\/29101"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/29076"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=29062"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=29062"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=29062"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}