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Bermuda braces for Hurricane Florence

By: Dr. Jeff Masters, 2:16 PM GMT on September 10, 2006

Today marks the peak day of the Atlantic hurricane season, and we've got the second hurricane of the season to watch now. Hurricane warnings are flying in Bermuda, and the island is bracing for what may be a direct hit by a Category 2 Hurricane Florence on Monday. Florence has an impressive appearance on satellite imagery this morning, with a large 50-mile diameter eye, an outflow channel at upper levels well established to the north, and a smaller one to the east. Given the very large size of the eye, it appears likely that at least a portion of Bermuda will be affected by the eyewall when Florence makes its closest approach Monday. Satellite intensity estimates are steadily increasing, but we'll have to wait until the Hurricane Hunters arrive back at the storm around 2pm EDT this afternoon to see how much intensification has occurred. The last Hurricane Hunter mission departed the storm at 3:30am EDT this morning. One can see some impressive rain bands enveloping the island on Bermuda radar and the Bermuda radar animation.


Figure 1. Latest satellite image of Florence, updated every 1/2 hour.

Florence has a very large swath of tropical storm force winds that have been blowing for many days over a huge stretch of ocean. These factors, when combined with the storm's expected intensification into a Category 2 hurricane, will create very high ocean swells that will impact the entire Atlantic coast from the Lesser Antilles to Canada. The highest seas can be expected from North Carolina to Newfoundland, with five to ten foot seas common in many nearshore areas. Twelve foot seas are expected off Cape Hatteras by Tuesday. The wave height forecast animation from the global wave model run by the National Weather Service is most impressive, and predicts wave heights up to 30 feet offshore the Newfoundland coast on Tuesday. Bermuda can expect waves of 15-25 feet on top of a 6-8 foot storm surge on Monday when the center of Florence passes.

Elsewhere in the tropics
An area of disturbed weather 900 miles east-southeast of Florence has a pronounced surface spin that one can see on visible satellite imagery, and was declared "Invest 93L" by NHC on Saturday. Wind shear has fallen to just 10 knots over this disturbance today, and some slow development is possible as it follows the a track similar to Florence. This storm may be a threat to Bermuda, but probably nowhere else.

There are no other threat areas in the Atlantic to discuss. The computer models forecast a new development off the coast of Africa by the middle of next week, but anything developing in this region is likely to recurve out to sea.


Figure 2. Preliminary model tracks for Invest 93L, 900 miles east-southeast of Florence.

Hurricanes and Bermuda
Hurricanes and Bermuda are no strangers. Since 1551, at least 65 tropical storms and hurricanes have hit the island. Twenty-five of these were major hurricanes. In the past century, the most severe hurricane to hit was the Havana-Bermuda Hurricane of October 22, 1926. This Category 4 storm struck the island with 135 mph winds and killed 88 sailors on a British war ship moored in the harbor that capsized and sank. Since the naming of hurricanes commenced in 1950, the only Bermuda hurricane to gets its named retired was Hurricane Fabian, which struck the island as a category 3 hurricane on September 5, 2003. According to NHC's final report on Hurricane Fabian, the hurricane's eye scraped the west side of the island, bringing the storm's worst winds in the right front quadrant over the island. Sustained winds of 115 mph and a storm surge of 10 feet caused over 300 million in damage and killed four. Battering waves 20-30 feet high affected the south shore of the island.

PBS television show tonight
Some Public television stations will be carrying the show, "Anatomy of a Hurricane", tonight at 10:30pm. Here's their description of the show:

This documentary program goes inside the National Hurricane Center in Miami, Florida, during the 2004 hurricane season. Tune in to get a revealing look at the stressful work of the dedicated staff who deal with unique and unexpected challenges and struggle to make the most accurate predictions. (CC, Stereo)
http://www.pbs.org/stationfinder/stationfinder_relocalize.html

It should be a great look inside at what goes on at the NHC during a big storm!

I'll have an update late tonight or early Monday morning.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.