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Posted at 02:33 PM ET, 09/06/2011

Hurricane Katia to pass between East Coast and Bermuda; new areas of tropical concern brewing


Satellite image of Katia (bottom right) and the remnants of tropical storm Lee (left) at 11:45 a.m. Tuesday ( NOAA’s Environmental Visualization Laboratory )

Category 1 Hurricane Katia has begun the long road to recurvature out to sea and is expected to pass between the United States and Bermuda on Wednesday night. Its maximum sustained winds decreased early Wednesday to 90 mph.

Track guidance is well-clustered around the idea that Katia will get no further west than 70°W longitude (same longitude as Cape Cod, Ma. but several hundred miles south) before taking a sharp right turn early Friday out over the open Atlantic. It should gradually weaken as it encounters colder water starting Thursday.

Over the next several days, Katia will trigger smallcraft advisories all along the Eastern seaboard for 15-25 mph north winds and large offshore swells in the 10-15 ft range. There will also be a higher than average risk for rip currents at the beaches from Florida to Maine.

The local weather service in Bermuda is expecting somewhat more noticeable impacts from Katia, with rough offshore seas of 12-18 ft and 25-35 mph winds. A tropical storm watch is in effect for the island according to the National Hurricane Center.


Steering flow around the remnants of tropical storm Lee will keep Katia out to sea (NOAA)
We can thank former tropical storm Lee for helping to create the steering currents that will protect the U.S. from a Katia landfall. High altitude southwesterly winds in association with the remnants of Lee (shown in red) are now spreading across the eastern United States. This offshore flow aloft will not allow Katia within several hundred miles of our shores.

With the peak of the hurricane season yet to come, it’s no surprise that other parts of the tropical Atlantic are also cooking with activity. NHC has identified another disturbance, known as AL95, that has the potential to develop further.

Still way out in the eastern Atlantic, it has a 90% chance of becoming a tropical depression or storm. It is likely earn the name tropical storm Maria. It’s too soon to speculate about whether it will impact the East Coast but, like most of its predecessors this year, will probably edge north of west in the days ahead.


Satellite image showing active tropical systems. (NOAA)

The last area of interest …for now… is located in the southwestern Gulf of Mexico (noted by the yellow ? in the satellite picture above).

A “cold” front (yes, can you believe it?) has just made it all the way down to 20°N, well past the Texas coast, in association with the backside of Lee’s large circulation. Sometimes, these dying fronts maintain a narrow, low-altitude cyclonic (counterclockwise) swirl around them even though the fronts themselves are well detached from their parent systems. And sometimes, over warm waters and weakly-sheared environments (like over the Gulf of Mexico now), these shallow, slowly-rotating features can develop into tropical cyclones. The NHC gives this a 30% chance of happening in the next 48 hours.

We will be watching this for you closely over the coming days.

By  |  02:33 PM ET, 09/06/2011

Categories:  Tropical Weather, Latest

 
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