{"id":410,"date":"2007-05-17T22:40:50","date_gmt":"2007-05-17T22:40:50","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/2007\/05\/17\/occluding-cyclone-in-the-gulf-of-alaska\/"},"modified":"2007-06-02T04:44:13","modified_gmt":"2007-06-02T04:44:13","slug":"occluding-cyclone-in-the-gulf-of-alaska","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/410","title":{"rendered":"Occluding cyclone in the Gulf of Alaska"},"content":{"rendered":"

\"GOES-11
\n<\/a><\/p>\n

GOES-11 6.7\u00c2\u00b5m “water vapor channel” imagery (above; QuickTime animation<\/a>)<\/strong><\/em> revealed a textbook signature of an occluding cyclone over the Gulf of Alaska on 17 May 2007<\/strong><\/a>. A dry slot<\/strong><\/a> begins to interact with a baroclinic leaf<\/strong><\/a> feature after 00:00 UTC, with a distinct cloud head or “comma head”<\/strong><\/a> forming after 06:00 UTC. After 12:00 UTC, the characteristic “dry swirl”<\/strong><\/a> pattern is evident on the water vapor imagery, indicating that the cyclone was entering the occluded phase of its life cycle.<\/p>\n

A classic hook-shaped pattern was also seen on AWIPS imagery of the DMSP SSM\/I rainfall rate product (below)<\/strong><\/em>, although rainfall rates were fairly light (in the 1-2 mm per hour range). NOAA Ocean Prediction Center<\/strong><\/a> guidance was forecasting gale<\/strong><\/a> and storm<\/strong><\/a> force winds in the northwestern quadrant of the occluding cyclone.<\/p>\n

\"DMSP<\/a><\/p>\n

==================================================<\/p>\n

\"GFS90<\/a><\/p>\n

A cross section<\/strong><\/a> oriented west to east through the cyclone at 18:00 UTC using AWIPS GFS90 model fields indicated that the dynamic tropopause (taken to be 1.5 Potential Vorticity Units, purple to blue enhancement, above<\/strong>)<\/em> was fairly low across the region of the cyclone (below the 500 hPa pressure level), with a hint of stratospheric air (greater than 1.5 PVU) extending downward to near the surface. A corresponding cross section of Relative Humidity (below)<\/strong><\/em> showed the very dry air (RH values less than 20%, orange to red enhancement)<\/em> associated with the elevated dry slot that was wrapping around the cyclone.<\/p>\n

\"GFS90<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

GOES-11 6.7\u00c2\u00b5m “water vapor channel” imagery (above; QuickTime animation) revealed a textbook signature of an occluding cyclone over the Gulf of Alaska on 17 May 2007. A dry slot begins to interact with a baroclinic leaf feature after 00:00 UTC, with a distinct cloud head or “comma head” forming after 06:00 UTC. After 12:00 UTC, […]<\/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":[10,18,8,26],"tags":[],"class_list":["post-410","post","type-post","status-publish","format-standard","hentry","category-general-interpretation","category-goes-11","category-marine-weather","category-poes"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/410","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=410"}],"version-history":[{"count":0,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/410\/revisions"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}