I want to say that your flight will fly north of the jets (because the jets are eastbound), which could mean a very nice flight. It could vary though, depending on the route taken. So could be super awesome, or have some occasional light to moderate, though I'm leaning towards decent.
We flew just south of greenland, on what was track C at the time I believe. Flight was super super smooth, seatbelt light was never on once.
FWIW, I've crossed the atlantic 12 times now with Swiss International, (6 times round trip), many of them in the dead of winter, and they've all been really pleasant and smooth, interesting considering all the atlantic winter horror stories I've heard. Maybe I've just gotten lucky with them, or maybe the Swiss are on to something!?