Atlantic Hurricane Protection Set to Expire Aug. 17

August 10, 2011; 10:02 AM ET
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The dip in the jet stream along the East Coast is forecast to weaken and shift farther west for a time later in the month. This typically helps to "draw in" tropical systems toward the Southeast U.S. coast.

The next week will bring a minimal threat of hurricane landfall to the U.S. mainland. However, that hurricane protection is set to expire Aug. 17.

Thus far through the 2011 Atlantic hurricane season, a zone of high pressure has been acting like a giant roadblock from tropical systems over the U.S. mainland.

The zone of high pressure has forced tropical systems to ride well to the south or be turned away to the east. However, changes are brewing.

An area of fair weather over the central Atlantic, known as the Bermuda High, will back out to the east, while a high pressure over the South Central states will drift farther west.

While the risk of weak, near-shore tropical cyclone formation will continue through August, this split will open the door for possible attack by tropical systems on the U.S. from the eastern Gulf of Mexico to part of the Atlantic Seaboard.

Meanwhile, the Cape Verde season continues to ramp up with tropical waves rolling off the coast of Africa every few days. Steering currents guide these systems along to the west, where they either continue west into the Caribbean or take one of several offramps north of the Antilles.

During the middle of August, the Bermuda High typically migrates farther east. This year, this shift seems ready to take place right on schedule.

There is some indication that one or more of these waves will ramp up and become a named tropical system. Of these, one system could make a run just off the east coast of the U.S. during the second half of next week.

According to Tropical Weather and Hurricane Expert Dan Kottlowski, "While it is very questionable as to whether this particular system would make landfall, some effects from any system just offshore would include building waves and an uptick in rip current concerns on the Atlantic beaches."

During the second half of next week, the split in the high pressure area will develop, but it could still take another week or more until tropical systems populate the void. Even with the split, tropical systems could still be turned away at the last minute.

According to Long Range Weather Expert Paul Pastelok, "Even with the split developing in high pressure, enough of that fair weather system is likely to remain farther west, continuing to steer tropical systems away from Texas."

Western Weather Expert Ken Clark added that the "super" high pressure area over the South Central states has been very persistent this summer.

"Some computer models are even rebuilding this high pressure area from the southern Plains to the eastern U.S. later this month," Clark said.

At any rate, whether you live along or are heading to the Atlantic and eastern Gulf beaches of the U.S., the Atlantic and Caribbean islands and Atlantic Canada, the tropics bear close watching as August continues and the heart of hurricane season approaches.


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