Hurricane Isabel was a classic Cape Verde storm that rapidly intensified into a Category Five Hurricane on the Saffir-Simpson Scale before making landfall as a Category Two Hurricane along the Outer Banks of North Carolina in September, 2003. The storm was quite unique by becoming one of the rare hurricanes to sustain Category Five Hurricane intensity for close to 30 hours.
Isabel captured a lot of media attention, and was probably the most powerful storm to hit North Carolina since Hurricane Hazel in 1954. It also affected other areas such as Maryland, Pennsylvania, Ohio, Virginia, and West Virginia while directly or indirectly causing deaths in New Jersey, New York, Rhode Island, Florida, and the District of Columbia. Hurricane Isabel, at its maximum strength, marked the most powerful storm in Atlantic Basin since Hurricane Mitch in 1998.
Hurricane Isabel originally formed as a modest tropical wave off the West Coast of Africa on September 1st, 2003. Over the next several days it would go through the trial and tribulations that many, if not all of the hundred or so tropical waves go through each Atlantic Hurricane Season. Then, on the sixth of September, it became a tropical depression with winds of 35 mph, and a minimum central pressure of only 1009 millibars, or 29.80 inches of Hg.
Isabel quickly grew into a tropical storm. Within six hours of being born, it became a named storm with winds of 40 mph, and a pressure that had dropped to 1005 mb, or 29.68 inches of Hg. By the end of the first day in its long journey to the record books, Isabel had become already a rather modest tropical storm with winds of 65 mph, and its pressure continued to drop as it fell below 1000 mb.
On top of that, Isabel was in a very conducive area for development. Upper level winds were light, and sea surface temperatures adequately supported tropical development. By the middle of the day on September 7th, the developing system became a minimal hurricane with winds in excess of 75 mph. From that point until early in the morning on September 8th, Isabel continued a gradual increase in intensity with its winds just below major hurricane strength at 110 mph.
However, it was at this point, while it was being steered to the West-Northwest beneath the influence of a strong Bermuda high in the Central Atlantic, Isabel began undergoing rapid intensification from a strong Category Two Hurricane to a ultra powerful Category Five Hurricane on the Saffir-Simpson Scale. A Category Five Hurricane is the highest level of intensity that a hurricane can reach, and such a storm is capable of catastrophic damage.
Undergoing rapid intensification for a period of about 84 hours, Hurricane Isabel increased its sustained wind speeds some 55 mph while experiencing a tremendous drop in pressure of a staggering 51 millibars, or 1.53 inches of Hg to be at 915 mb, or 27.02 inches of Hg. (By the way, Hg is the symbol for Mercury on the periodic table for those wondering.)
This represented the lowest pressure and highest wind speed the storm would have during its lifetime. With its West-Northwesterly track, Isabel steered clear of the Leeward Islands of the Northeastern Greater Antilles including Puerto Rico and the Virgin Islands. During this period though, Hurricane Isabel achieved something quite rare. For over the next day, the powerful hurricane was able to sustain its super intensity with sustained winds still peaking at over Category Five strength.
According to information provided by the Weather Channel at the time, Hurricane Isabel ended up being among the four longest lasting hurricanes at Category Five intensity by lasting 36 hours at that strength. It is actually quite unusual for a storm to last at this intensity because of changes in upper level winds, sea surface temperatures, and things such as eyewall replacement and concentric eyewalls.
But, in the early morning hours of September 13th, Hurricane Isabel finally dropped from Category Five intensity. It would regain this intensity again for a brief period in the late afternoon on the 13th, and at the same time on the 14th. However, after that, it would gradually begin to weaken as it headed toward landfall along the Southeastern United States coastline.
As the hurricane headed toward the outer westward portion of the subtropical ridge in the Central Atlantic, the storm turned West-Northwestward, and then more towards the north. It also began encountering more vertical shear, which caused the once powerful system to weaken below major hurricane status on September 15th. Nevertheless, Isabel remained a threat as it packed winds between 105 and 110 mph, which made it Category Two on the Saffir-Simpson Scale.
Even though the storm had become weaker, Isabel grew tremendously in size, which does tend to happen during a storm's decline. Hurricane Isabel was able to maintain its Category Two intensity with winds between 100 and 105 mph as it made landfall along the Outer Banks of North Carolina near Drum Inlet. Isabel ended up leaving behind some $3.37 billion dollars in damage, and a total of 50 deaths either by direct or indirect impact from the storm. Eight states received damage including North Carolina, Virginia, West Virginia, Maryland, Delaware, Pennsylvania, New Jersey, and New York.
The storm also had impact on places such as Ohio, Rhode Island, and Florida. As perhaps the most intense hurricane to affect the North Carolina and Virginia area since Hurricane Hazel in 1954, and the Great Chesapeake Hurricane of 1933, Hurricane Isabel still managed to leave its mark despite mercifully losing its punch. The storm also had a very long life by lasting two weeks as a tropical storm or hurricane, and it had a three week life span from the time it was a mere tempest off the coast of Western Africa.
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