Sometimes AS2K4 will display wind direction as a negative heading. I received the following data for my winds aloft report at KSEA (100350Z):FL030: -001/13 (-4.3) FL060: 304/17 (-9.2) FL090: 300/19 (-13.2)FL120: 297/30 (-20.2) FL180: 301/39 (-31.6) FL240: 301/51 (-40.9)FL300: 300/57 (-46.5) FL340: 302/60 (-51.5) FL390: 301/55 (-49.0)***Route-Based Wind Smoothing features enabled - processed data may not match real-time reports!***For absolute accurate data, turn off Wind Smoothing...

Thanks. That is strange looking.JimActiveSky Support

I have encountered that as well Jim, but not very often. I also seem to remember having some odd wind speeds showing up in the WX briefing.Perhaps an error trap code or similar needs adding or investigating to stop incorrect values being used.

It's probably a mag var. problem. The mag var at KSEA is almost -20 degrees I think.