Hurricane Florence lashes Bermuda

Hurricane Florence is lashing Bermuda with winds just below hurricane force. The Bermuda airport at 10:55am local time had sustained winds of 66 mph, gusting to 83 mph. The airport is at the extreme eastern end of the island, and the large eye of Florence is passing just to the west. Thus, the western end of the island may be experiencing much higher winds. Bermuda is now feeling the worst Florence has to dish out, and residents can rest assured that a repeat of the pounding delivered by Category 3 Hurricane Fabian in 2003 will not occur. The primary threat from Florence is an expected 6-8 foot storm surge, topped by large battering waves up to 20 feet high. Florence's winds should cause relatively minor damage. Bermuda's infrastructure is well able to withstand winds of Category 1 force, since much of the utility lines are buried underground, and the building codes demand that structures be able to withstand 110 mph Category 2 hurricane winds.

Florence's appearance on satellite imagery has degraded considerably this morning, probably due to an increase in wind shear to 20 knots. The eye is no longer visible, and the upper level outflow is not as impressive. The Hurricane Hunters reported a large gap on the south side of the eyewall on their recent passes, and this can be seen on the Bermuda radar (Figure 1) and the Bermuda radar animation. The Bermuda radar failed at 4:07am EDT this morning.


Figure 1. Last radar image of Florence at 4:07am EDT (10:07 GMT) before the radar failed.

Although Florence is weakening, she will continue to be a prodigious wave maker. Florence's large swath of tropical storm force have been blowing for many days over a huge stretch of ocean. High ocean swells will continue to impact the U.S. East Coast and Canadaian Maritime provinces the next two days. Five to ten foot seas will be common in many nearshore areas on 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. Florence is expected to gradually weaken as wind shear increases and ocean temperatures decrease, and will pass close or over Newfoundland later this week as a powerful extratropical storm with 60 mph winds.

Bermuda's next worry: Tropical Depression Seven
Florence's acceleration to the north has allowed the area of disturbed weather a few hundred miles northeast of the Lesser Antilles Islands a chance to develop. Visible satellite imagery shows improved organization, and satellite classification of the storm's intensity already put this system at tropical storm strength. A QuikSCAT pass from 5:26am EDT showed numerous wind vectors in the 40-55 mph range, but confined to the southeast side of the circulation center. The Hurricane Hunters will investigate this system at 2pm EDT today. NHC may wait until then to decide whether or not to upgrade this system to Tropical Storm Gordon. Wind shear has fallen to just 10 knots, the waters are a warm 29C, and some continued development is likely today. Tropical Depression Seven is likely to follow a track similar to Florence, and may be a threat to Bermuda.

Bermuda's worry after that: a new African wave
A strong tropical wave with impressive rotation and plenty of intense thunderstorm activity is emerging from the coast of Africa today. Several of the reliable computer models are forecasting that this will develop into a tropical storm or hurricane that heads westward across the Atlantic. Wind shear is a low 10 knots, and water temperatures are warm. If this system does develop, it would likely recurve out to sea and not affect any land areas--expect perhaps Bermuda. However, it is far too early to be confident of this.

Jeff Masters