cjzydeco
(Weather Guru)
Sat Aug 18 2007 01:04 PM
Re: Hurricane free zone?

The area north of Jacksonville and south of Cape Romain, SC, is known as the South Atlantic Bight. Here is a quote from "The Natural History of Georgia's Barrier Islands" by Taylor Schoettle. It helps to explain why this geophysical area has a lower potential for hurricane strikes.

Quote:

Georgia's barrier islands are actually the midsection of a system of oak-shrouded, sandy barriers that extend from the middle of the South Carolina coast to the mouth of the St. Johns River in Jacksonville, Florida. Georgia is the most westward location of the Atlantic seaboard, placing its barrier islands in the approximate center of the inward-curving coastline known as the South Atlantic Bight and 60 to 70 miles from the edge of the continental shelf (continental slope).

This position of the barrier islands relative to the South Atlantic Bight affects Georgia's tides, waves, and incidences with hurricanes. As oceanic tides, having an average range of 2 to 3 feet, funnel into the bight, the water piles up on itself, creating an elevated tidal range of 6 to 9 feet and making Georgia's tides the highest of the Atlantic seaboard south of New York. The shallow slope of the continental shelf, averaging about 2 feet per mile, dissipates the energy of the large waves coming in from the open ocean. Waves move across the broad, shallow shelf waters and lose energy as they drag along the bottom and break over the many offshore shoals before arriving on beaches. Since the Gulf Stream, in its wandering way, basically follows along the edge of the continental slope, Georgia's shores are also remote from the Gulf Stream. Hurricanes that approach our shores from the Atlantic tend to veer northward as they follow the warm air over the Gulf Stream, frequently causing them to miss our small 100-mile-long shoreline and make landfall farther north or go out to sea.




I also seem to remember from my meteorology course at CofC that there is a transition between global wind belts that affects this area as well. The subtropical high pressure belt is located right around 30N (the latitude of Jacksonville). North of there, the prevailing westerlies tend to help bend storms back to the east. The real mets probably have a better grasp on this than I, and I may be way off base.



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