{"action":"created","issue":{"url":"https://api.github.com/repos/wmo-im/iwxxm/issues/57","repository_url":"https://api.github.com/repos/wmo-im/iwxxm","labels_url":"https://api.github.com/repos/wmo-im/iwxxm/issues/57/labels{/name}","comments_url":"https://api.github.com/repos/wmo-im/iwxxm/issues/57/comments","events_url":"https://api.github.com/repos/wmo-im/iwxxm/issues/57/events","html_url":"https://github.com/wmo-im/iwxxm/issues/57","id":272682075,"number":57,"title":"Add support for Amd 77 TC SIGMET center positions and CB positions","user":{"login":"braeckel","id":531521,"avatar_url":"https://avatars0.githubusercontent.com/u/531521?v=4","gravatar_id":"","url":"https://api.github.com/users/braeckel","html_url":"https://github.com/braeckel","followers_url":"https://api.github.com/users/braeckel/followers","following_url":"https://api.github.com/users/braeckel/following{/other_user}","gists_url":"https://api.github.com/users/braeckel/gists{/gist_id}","starred_url":"https://api.github.com/users/braeckel/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/braeckel/subscriptions","organizations_url":"https://api.github.com/users/braeckel/orgs","repos_url":"https://api.github.com/users/braeckel/repos","events_url":"https://api.github.com/users/braeckel/events{/privacy}","received_events_url":"https://api.github.com/users/braeckel/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":{"url":"https://api.github.com/repos/wmo-im/iwxxm/milestones/2","html_url":"https://github.com/wmo-im/iwxxm/milestone/2","labels_url":"https://api.github.com/repos/wmo-im/iwxxm/milestones/2/labels","id":2649983,"number":2,"title":"IWXXM 3.0rc1","description":"Test version IWXXM 3.0 RC1 available for testing\r\n\r\nAgreed at WG-MIE Montreal 2017: https://wis.wmo.int/file=3559","creator":{"login":"marqh","id":1557321,"avatar_url":"https://avatars3.githubusercontent.com/u/1557321?v=4","gravatar_id":"","url":"https://api.github.com/users/marqh","html_url":"https://github.com/marqh","followers_url":"https://api.github.com/users/marqh/followers","following_url":"https://api.github.com/users/marqh/following{/other_user}","gists_url":"https://api.github.com/users/marqh/gists{/gist_id}","starred_url":"https://api.github.com/users/marqh/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/marqh/subscriptions","organizations_url":"https://api.github.com/users/marqh/orgs","repos_url":"https://api.github.com/users/marqh/repos","events_url":"https://api.github.com/users/marqh/events{/privacy}","received_events_url":"https://api.github.com/users/marqh/received_events","type":"User","site_admin":false},"open_issues":33,"closed_issues":4,"state":"open","created_at":"2017-07-19T13:35:26Z","updated_at":"2017-11-21T22:12:24Z","due_on":"2018-04-01T07:00:00Z","closed_at":null},"comments":7,"created_at":"2017-11-09T18:58:58Z","updated_at":"2017-11-22T01:22:00Z","closed_at":null,"author_association":"OWNER","body":"In SIGMET in Amd 77 two important pieces were added for TC SIGMETs that do not appear to representable in IWXXM 2.1:  the position of TC CENTREs outside of an OBS or FCST section and reporting CB positions instead of TC positions.  The differences in Amd 77 may be viewed on p40-48 (PDF pages 62-70) of [this document](https://www.icao.int/APAC/Meetings/2016%20MET_SG20/IP05_AI.4%20ICAO%20-%20Review%20AM%2077%20-%20Annex%203.pdf).\r\n\r\nSee the screen shot of the TC SIGMET example below.  The important implications of this example to IWXXM 2 are that there is a reported *TC CENTRE* position (without time information), an OBS 16Z *CB* position, then a 22Z FCST *TC CENTRE* position.  Note that the information carried in these three positions alternate from TC CENTRE to CB position and back to TC CENTRE.  \r\n\r\n![screen shot 2017-11-09 at 11 05 33 am](https://user-images.githubusercontent.com/531521/32622782-476817d0-c541-11e7-9813-0d625946e8d9.png)\r\n\r\nThere are several changes that may be required:\r\n- a way to represent a TC CENTRE position outside of an OBS or FCST block (\"PSN N2706 W07306\").  The most straightforward mechanism (not necessarily the best mechanism) would be a new \"tropicalCycloneCentrePosition\" on TropicalCycloneSIGMET\r\n- distinguishing between TC CENTREs and CBs conditions/positions (\"CB OBS AT 1600Z N2706 W07306 CB WI 250NM OF TC CENTRE\" and \"FCST AT 2200Z TC\r\nCENTRE PSN N2740 W07345\").  Currently the IWXXM SIGMET would be reported as a TC phenomena with no indication in the analysis and/or forecastPosition elements as to whether the reported locations are CBs or TC CENTREs.  With TC SIGMETs as they stand today, *implicitly* the iwxxm:analysis element would always indicate CB and the forecastPosition would always indicate TC CENTREs.  However this implicit interpretation is almost certain to result in confusion and issues for SIGMET consumers, especially since in other AIR/SIGMET cases the interpretation is always that the reported locations are always of the \"root\" SIGMET phenomena (like TS, VA or TC positions)\r\n- updates to any existing TC SIGMET examples to be consistent with the new approach\r\n- documentation updates"},"comment":{"url":"https://api.github.com/repos/wmo-im/iwxxm/issues/comments/346213861","html_url":"https://github.com/wmo-im/iwxxm/issues/57#issuecomment-346213861","issue_url":"https://api.github.com/repos/wmo-im/iwxxm/issues/57","id":346213861,"user":{"login":"blchoy","id":30064374,"avatar_url":"https://avatars1.githubusercontent.com/u/30064374?v=4","gravatar_id":"","url":"https://api.github.com/users/blchoy","html_url":"https://github.com/blchoy","followers_url":"https://api.github.com/users/blchoy/followers","following_url":"https://api.github.com/users/blchoy/following{/other_user}","gists_url":"https://api.github.com/users/blchoy/gists{/gist_id}","starred_url":"https://api.github.com/users/blchoy/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/blchoy/subscriptions","organizations_url":"https://api.github.com/users/blchoy/orgs","repos_url":"https://api.github.com/users/blchoy/repos","events_url":"https://api.github.com/users/blchoy/events{/privacy}","received_events_url":"https://api.github.com/users/blchoy/received_events","type":"User","site_admin":false},"created_at":"2017-11-22T01:22:00Z","updated_at":"2017-11-22T01:22:00Z","author_association":"OWNER","body":"The need to describe two phenomenon (viz TC position and CB) separately within an OBS and FCST section actually violates the existing SIGMET data model.  In fact, one can still use a TC SIGMET + WS SIGMET (for thunderstorm) to describe this situation.  I can imagine the latter presentation is less preferable in story telling but if the concept is adopted, it will immediately trigger other possible combinations (may be volcanic ash and thunderstorms for a violently erupting volcano?).  I think we need to clear up the concept with relevant ICAO groups and delaying it IWXXM 3 is a good choice."}}
{"actor":{"display_login":"blchoy"}}