Why did Dorian stall, turn?
The 2019 hurricane season will forever be remembered for the destruction to Great Abaco Island and Grand Bahama Island produced by Hurricane Dorian.
Dorian was a Category 5 hurricane with winds of 178 mph when it made landfall on the east side of Great Abaco Island. Catastrophic damage occurred across the extreme northern Bahamas with peak winds reaching 184 mph just prior to landfall.
A devastating storm surge combined with torrential rainfall brought the northern islands to their knees.
Dorian was earlier forecast to move across the northern islands and then slam into Brevard County within 12 hours, but Dorian stopped.
The Florida peninsula and especially Central Florida dodged a bullet with Dorian. The strongest wind gust across Florida produced by Hurricane Dorian was 69 mph at New Smyrna Beach. Why did Dorian stop?
The steering currents collapsed.
All tropical systems are either pushed or pulled by steering currents that are altered by cold fronts, high-pressure centers and developing nearby storm systems.
While Dorian was moving steadily west toward Florida, the high-pressure center to the north of Dorian began to weaken. This weakening of the high pressure reduced Dorian’s forward speed to less than 3 mph.
This slowing caused Dorian to pound Great Abaco Island with tropical-storm force winds or greater for three days.
The high pressure weakened further and caused Dorian to stall out right over Grand Bahama Island. As Dorian continued to spin in the same general area for nearly two days, the cool water coming up robbed the energy from Dorian and caused the winds to decrease to 161 mph.
The steering and blocking of the high-pressure center shifted east and allowed a small opening for Dorian to turn north and carry it away from the Central Florida east coast.
This slowing and then turning caused Dorian’s turn to the north to be nearly a 90-degree angle or right angle … remarkable.