Tropical Storm Gabrielle visits Bermuda


Bermuda Weather Service Radar at 1:23am September 11th 2013 showing the center of Tropical Storm Gabrielle just offshore of the west end of Bermuda.
Bermuda Weather Service Radar at 1:23am September 11th 2013 showing the center of Tropical Storm Gabrielle just offshore of the west end of Bermuda.

Tropical Storm Warnings were discontinued for Bermuda at 9am on September 11th as Tropical Storm Gabrielle began to move away and tropical storm conditions were no longer observed or expected on island or in the marine area. Gabrielle made a very close approach to Bermuda just after midnight on September 11th. The storm’s center was within 25miles of the airport location at midnight between the 10th and 11th. Fortunately, wind shear increased from the west and much of the deep convection associated with Gabrielle was taken away to the east of the storm and therefore away from the island. This deep convection was not and has not been able to reestablish over the center. This meant that the storm weakened a bit on its approach, and has continued to weaken to a Tropical Depression as of the latest midnight advisory (Bermuda time) from the National Hurricane Center.

Despite the slight weakening, Tropical storm conditions were observed in Bermuda, especially in exposed areas either on hill tops or on the coast in areas of onshore winds. Gusts at or near tropical storm strength were observed in more sheltered areas. The sustained winds peaked at 45mph with gusts to 56mph at the airport (Climate), and were sustained at 53mph with gusts to 68mph at the elevated and thus more exposed site at Commissioner’s Point in Dockyard (Island Obs). Tropical Storm conditions start when sustained winds reach 39mph or greater. My very poorly exposed personal anemometer recorded peak gusts of 35mph, located in central Devonshire. Tropical Storm conditions between the 10th and 11th did result in several small isolated power outages and some minor tree damage. The Royal Gazette reports that those power outages were restored by the time the Tropical Storm Warnings were ended at 9am on the 11th.

The lowest pressures observed in Bermuda were between 1014 and 1015mb – fairly high considering Hurricane Hunter missions measured pressures as low as 1008mb and the center was so close to the island. 1014.8mb was officially reported in observations at the airport (may have been lower in between observations) while the minimum reported at my station was 1013.8mb.

In terms of rainfall, 0.49″ (Climate) of rain fell during the 10th, while more rainfall was observed at the airport on the 11th – to be determined at the end of the climate day. And further heavy, potentially squally showers and thunderstorms are possible as Gabrielle slowly pulls away to the northwest and north. Several outer bands associated with the storm remain to the south and east of Bermuda and will likely add to the rainfall totals as they cross the island as Gabrielle moves away and takes them with it.

Overall Gabrielle was a very well forecast storm in terms of track, with the storm staying within the very first forecast track issued by the National Hurricane Center. This came with accurate timings six days in advance and despite the storm becoming poorly defined as it exited the Caribbean. The Bermuda Weather Service forecast included the possibility of this storm impacting Bermuda from the time it formed in one way or another and so in that regard was also well forecast. Stay tuned to the latest official forecast and advisory/warning products specific for Bermuda at the Bermuda Weather Service. Additional tropical cyclone information, including products for recently formed Hurricane Humberto in the distant east Atlantic (not a threat to Bermuda at this time), can be found at the National Hurricane Center‘s website.

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