# Cloudless sky in synop message?

SYNOP code (see http://weather.unisys.com/wxp/Appendices/Formats/SYNOP.html) has a field for describing cloud types by different levels, given as "8NCCC" (see link for further info, Cloud type information). And there is a program for converting SYNOP to XML, http://metaf2xml.sourceforge.net/, which in most cases seems to work. However, when the cloud code is "80000", which IMO is correct for a cloudless sky, then the program says "invalidFormat". So does anybody know if "80000" is correct or not?

Edit: "AAXX 11003 63658 32970 00905 10207 20060 38860 48492 80000 333 58002 555 10130" Real life example showing that total cloud cover in previous section is also 0. Does this mean that when total cloud cover = 0 is already given, then the section about cloud types is anyway meaningless?

• There us also total cloud cover in part 'Nddff', perhaps the converting system is smart enough to yell error if these two informations aren't in agreement. – Communisty Apr 12 '18 at 13:01

Yes, in your example, the group should have been omitted. From the WMO Publication No. 306 - Manual On Codes - Volume I.1 - Part A, Section A, FM 12 SYNOP:

12.2.7 Group 8NhCLCMCH

12.2.7.1 This group shall be omitted in the following cases:

(a) When there are no clouds (N = 0);

(b) When the sky is obscured by fog and/or other meteorological phenomena (N = 9);

(c) When the cloud cover is indiscernible for reasons other than (b) above, or observation is not made (N = /).

metaf2xml tries to stick to the Manual but tolerates deviations, so the group is recognized but marked as invalid.

• For questions about or things not working in metaf2xml there's always the ticket system for the project at SourceForge. – Thomas May 27 '18 at 6:12