ORLANDO, Fla. – Dorian has been stationary over Grand Bahama Island for about 24 hours. Dorian becoming stationary over the Bahamas was expected to happen. The next stage of its life consists of a slow turn to the north paralleling the east coast of Florida. But how do we know?
Computer forecasts have been hinting at this turn for the last several days. Data from weather balloon launches on the U.S. mainland and over the Atlantic from Hurricane Hunters have sampled the environment around Dorian.
That data then gets put into forecast models. Over the weekend, data suggested that a dip in the jet stream would weaken a large area of high pressure halting Dorian's westward movement toward Florida. This weakening of Dorian's steering currents likely spared Florida from a direct hit, but is also the reason Dorian stalled out over the Bahamas.
The weakened high over Bermuda will sink far enough south, picking up Dorian and steering it north just off the Florida. If that high pressure remained strong and connected with high pressure over the U.S., we would likely be talking about Dorian making a landfall somewhere on the Florida coast.
Better data from those balloon launches and hurricane hunters allowed for improved forecasts over the last few days.