Some have asked “why the abrupt turn north?”
The answer lies high up in the atmosphere as the ridge of high pressure that has been steering Dorian steadily (and slowly) west begins to weaken by Sunday night into Monday. You can see this with the red “blob” of higher heights- indicating higher pressure, fades away. This ridge will still be there, but it will be noticeably weakened and actually back off towards the east. This will allow Dorian to get caught up in the clockwise motion around the “weakened ridge”and lead to that steering flow north.
Why the change in the forecast? Dorian slowed down and allowed for that ridge to break down. If it approached faster, it would have likely continued on that western trajectory through Florida.
This northwards transition is expected to occur Monday and will dictate impacts to the Lowcountry and the southeast coast. As such, we’ll have a better idea of the impacts then, but recent forecast have been trending towards a more positive end solution for the area.