The calibration system we use today to convert the data measured by the plane into wind speeds cranked out numbers over 200 mph in Dorian, which gave everybody pause.Skill or Luck?: How NHC’s Hurricane Track Forecasts Beat the Models In the super-intense hurricanes we’ve seen over the past few years - Irma as it was approaching the Caribbean islands, Michael as it was approaching Panama City, and now Dorian near the Bahamas - the instruments on the Hurricane Hunters that estimate the wind speed at the ocean’s surface have been showing some extraordinarily high values. No doubt, scientists will be researching what went wrong with both the track and intensity models for Dorian for some time.Īn important research project is underway that could change Dorian’s peak-intensity number. Even with the slight forecast miss offshore of Florida and the dramatic deviation in the Caribbean, the overall average track forecast errors for Dorian were quite low. We know that modern science delivers much better forecasts of where a hurricane is going than how strong it is going to get. The 185-mph peak came right when the Category 5 hurricane was approaching Abaco in the northern Bahamas. The wind speeds on the left are in knots, so to get miles per hour, you multiply by 1.15. The graphic below shows that most of the computer models forecast Dorian to strengthen, but nothing close to what actually happened. As a result, the official National Hurricane Center forecast didn’t pick up on Dorian’s incredible intensity jump until it was already happening. None of the most reliable computer models came close to estimating the extreme increase in strength. That rule about weak systems is important to remember for the future.Īs far as how strong Dorian was going to be, during the time the hurricane was between the Caribbean and the Bahamas, the forecasts were terrible as well. In this case, not only was Dorian a weak tropical storm, it also tracked right over the tall mountains of the island of St. We always say forecasts for weak systems generally have much larger errors. You can see that they lined up well off Georgia and the Carolinas, but off Florida, the forecast tracks indicated that significant impacts along the coast were possible. In the plot below, the blue lines are the computer models, and the white line is Dorian’s final track. In the end, they were not all needed, but the best computer models forecast the center to track close to the coast, so there was no choice. Warnings were issued for Palm Beach County and points north on the Florida coast. There would have been time to adjust the warnings if Dorian had significantly deviated from the forecast track. There was confidence that the storm wasn’t going anywhere fast in the atmospheric environment of weak to nonexistent steering currents that was present over the Bahamas at that time. Comments on the format are appreciated.Posted by Bryan Norcross on Friday, ĭorian’s extremely slow movement helped. This video adds to the written post about the National Hurricane Center's final report on Hurricane Dorian. Hurricane Dorian Report Video Explanation This forecasting success saved the residents of Dade and Broward a lot of money and aggravation. To the good, it was very unusual to have a giant and powerful hurricane moving west across the northern Bahamas, and have no watches or warnings posted for Broward or Miami-Dade counties.

Essentially, Dorian refused to do what the computer forecast models said it would. Before the storm got the Bahamas, the system’s track and intensity were not well forecast. The report highlights the forecasting successes during Dorian and the challenges. That makes Dorian the strongest storm to hit the northern Bahamas in modern records. The assessment of the top wind-speed in Dorian came in at 185 mph - the same estimate the NHC forecasters made as the Category 5 hurricane was hitting Abaco Island. Information gathered from across the Caribbean, the Bahamas, Florida and up the coast to Canada is the final best estimate of exactly what happened over the three weeks from the time Dorian developed in the tropics until it dissipated in the North Atlantic. MIAMI – The National Hurricane Center’s final report on Hurricane Dorian is out.

Dorian hurricane track models