{"id":400,"date":"2007-04-20T18:40:50","date_gmt":"2007-04-20T18:40:50","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/2007\/04\/20\/the-first-tropical-cyclone-of-the-season\/"},"modified":"2007-05-07T04:02:42","modified_gmt":"2007-05-07T04:02:42","slug":"the-first-tropical-cyclone-of-the-season","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/400","title":{"rendered":"The first tropical cyclone of the season?"},"content":{"rendered":"

\"GOES-12<\/a><\/p>\n

\n

No…just a weak cyclonic vortex off the Atlantic coast of Florida that just happens to look<\/em> like<\/em> a tropical cyclone with an eye! GOES-12 visible imagery (above; Java animation<\/a>)<\/strong><\/em> shows the cloud swirl as it developed what appeared to be an “eye” on 20 April 2007<\/strong><\/a>. While this vortex was responsible for some weak banded offshore rain features (radar reflectivity image<\/strong><\/a>), the GOES-12 10.7 \u00c2\u00b5m IR brightness temperatures<\/strong><\/a> were still very warm (around 0\u00c2\u00ba C),<\/em> indicating a lack of deep convection. The vortex existed in a high-shear environment — around 90 knots on the CIMSS wind shear product<\/strong><\/a> (below)<\/strong><\/em> — which was not favorable for tropical cyclone development. In addition, the MODIS sea surface temperatures<\/strong><\/a> in that region were still below the 80\u00c2\u00ba F (26.7\u00c2\u00ba C)<\/strong> threshold generally considered necessary for tropical cyclone genesis, and GOES sounder total precipitable water values<\/strong><\/a> were only in the 20-30 mm (0.79-1.18 inch) <\/strong>range.<\/p>\n

\n

\"070420_15z_shear.gif\"<\/a><\/p>\n

\n

\n

\n

The history of this particular swirl is rather interesting. A Weather Channel Blog posting<\/strong><\/a> discussed a possible Mesoscale Convective Vortex (MCV)<\/em> origin; if we follow satellite imagery back in time for a day or two, the development of this feature appears to have been tied to a fairly large mid\/upper tropospheric cyclone that was just south of the Great Lakes on 18 April<\/strong><\/a> (QuickTime animations: GOES water vapor<\/strong><\/a> | GOES IR<\/strong><\/a>). A potential vorticity (PV)<\/em> anomaly associated with the cyclone shows up as a local maximum of GOES Sounder total column ozone (light green to red enhancement<\/em> on this QuickTime animation<\/strong><\/a>); a GFS model cross section through the region of the swirl at 18 UTC on 20 April (below)<\/strong><\/em> suggests that a PV “tail” lagging behind the main PV anomaly farther offshore may have played a role in helping to spin up the swirl.<\/p>\n

\n\"GFS<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

No…just a weak cyclonic vortex off the Atlantic coast of Florida that just happens to look like a tropical cyclone with an eye! GOES-12 visible imagery (above; Java animation) shows the cloud swirl as it developed what appeared to be an “eye” on 20 April 2007. While this vortex was responsible for some weak banded […]<\/p>\n","protected":false},"author":18,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[15,19,12,25,2],"tags":[],"class_list":["post-400","post","type-post","status-publish","format-standard","hentry","category-goes-sounder","category-goes-12","category-modis","category-satellite-winds","category-tropical-cyclones"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/400","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=400"}],"version-history":[{"count":0,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/400\/revisions"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=400"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=400"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=400"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}