The Wunderground and NOAA sites are not primary sources. The actual METARs are issued by the airport authorities, they are the primary source. I agree that a METAR without translation would not add much to the article for readers who don't understand the code, hence the translation. This is not synthesis as the source quoted shows the translation of each part of a METAR. In this case, it points towards the runway being wet as there had been recent rain (a contributory factor). I've heard on Pprune that the aircraft was landed hot and long, but this has not been added to the article as it is not from a source which Wikipedia deems reliable enough. Personally, I think that the METAR does add to the article. Perhaps it could be in a (sub)section of its own?     