I've heard of the high pressure ridge but can that force the storm either way... NE or SW? I gather from most here that it's more likely to force the storm SW. But, I'd sure like to hear more about this.
The general westward movement of low latitute huricanes is becuase the huricane is in the "westerlies", a west movement of air caused by the earths spin. As the huricane gains latitude (moves north) the earth spin will tend to make it want to move more to the north, this northward trend can be stopped by a high pressure ridge (think of it as a wall of air that the huricane can not get over), also the flow of air around a high is anti-cyclone which is clockwise and also tends to move Rita west.
Everything is pushing Rita west, something has to change quite a bit before Rita can move north and it doesn't look to me like anything is going to change at time soon.