Okay, I just Googled this to death and it turns out that indeed, the northers are called Christmas Winds in the Virgins. But these are the northers and not the tradewinds nor reinforced tradewinds. Like I wrote, the northers are the fronts coming down from the US east coast
and yes, they provide high winds and seas from the North.
In other places, the Christmas Winds are the reinforced tradewinds which, in the Caribbean
, always blow from the E-NE. There are no tradewinds blowing from the north.
Edit: I'm sailing in the Caribbean for 7 years now but never spend much time in the Virgins, let's say 4 weeks in all those years, so I never picked up that local variation in the meaning of Christmas Winds ;-)