All winds start of N-S in the Northern hemisphere....
As a result of the tropical cell [or whatever its called] which lifts warm air from the equator and dumps it up North, resulting in high pressure north of this zone and low pressure to the south of this zone and thus the quasi stationary polar front. When you get a disturbance in the QSP front, say a ridge of low pressure converges up into the northerly high pressure area, then coriolis acts on this causing rotation, and hence a low pressure area...Then the winds are determined by this low pressure area. In the summer the QSP front tends to be further north and in the winter further south, which is why in Europe we get more low pressure areas during the winter months. You also get a jetstream running along these quasi fronts....
I know what I'm trying to say....I just can't explain it very well
Bye
EA