It doesn't!

Of course knowing the GFS and its ability to chuck up ridiculous
situations out of the blue , maybe that's just what it is ;as
mischievous mirage.

It did the same on the 12z several nights ago where it gave us almost
an Easterly for Christmas only, without a bye your leave or apology,
never to show it again.
I believe this GFS computer is based in the US I would love to go
around there wherever it lives and give it a good kick in the hard
drives; bloody useless thing.
http://www.wetterzentrale.de/pics/Rtavn3721.png