Hurricane Dorian Sets Records

Dorian's Latest Forecast Track from the National Hurricane Center

Although Dorian has weakened considerably from its peak intensity as a Category 5 monster, it is still a powerful and dangerous storm.  Residents of the southeastern United States should be paying attention to local authorities for safety information.  It’s essential to rely on reputable sources of information like the National Weather Service and your local broadcast meteorologists for updates – such as my colleagues and I on the WUSA9 Weather Team.

When Dorian became a Category 5 hurricane on September 1, it became the fifth Category 5 hurricane to develop in the Atlantic Ocean Basin in the last four years.  That surpassed the previous record of three consecutive years (2003 – 2005) that Category 5 hurricanes developed in the Atlantic.  Hurricane Matthew developed in 2016, Irma and Maria in 2017 and Hurricane Michael just last October.  

Hurricane Dorian made landfall in the Bahamas with sustained winds of 185 mph.  That tied it with the 1935 Labor Day hurricane, which made landfall in the Florida Keys as the most intense landfalling hurricane in the Atlantic Ocean Basin.  It’s important to point out that it was the most intense based on wind speed and not air pressure.  Dorian’s minimum central air pressure of 910 millibars (mb) tied it with 2004’s Hurricane Ivan for ninth lowest on record in the Atlantic Ocean Basin.  Its maximum sustained winds of 185 mph also tied it with Hurricane Gilbert (1988) and Hurricane Wilma (2005) for second highest wind speeds in an Atlantic hurricane.  However, Gilbert and Wilma weakened slightly before making landfall.  Only Hurricane Allen (1980) had a higher sustained wind speed (190 mph) in an Atlantic storm.

Not only was Dorian the strongest hurricane on record to make landfall in the Bahamas, it continues to be a very slow moving storm.  According to Dr. Phillip Klotzbach of Colorado State University, “Dorian tracked only ~25 miles in 24 hours –the second shortest straight-line distance tracked by an Atlantic major hurricane in a 24-hour period since 1950…”  The slow moving hurricane prolonged the devastating effects of the storm and made forecasting its ultimate track more difficult.

One good thing about its slow movement has been the resulting upwelling.  Upwelling occurs when wind along the surface of the ocean displaces the water, causing cooler water from lower depths to rise to the surface.  That’s quite common in slow moving tropical systems and the cooler water eventually leads to the weakening of the hurricane.  

Although Hurricane Dorian is much weaker than at its Category 5 peak intensity, it’s still a large and dangerous storm.  The wind field has actually expanding from what it was earlier.  That means tropical storm force winds extend a greater distance from its center than they did earlier.