Gabrielle (2013)

A small low-pressure area that originated from a tropical wave off the west coast of Africa developed into a tropical depression about 100 nautical miles south-southeast of Puerto Rico at 1800 UTC on 4 September 2013. The system briefly organized and then weakened to a disturbance near the eastern tip of Hispaniola on 5 September. It moved northward and northeastward under upper-level steering currents, redeveloped into a tropical depression at 0000 UTC 10 September about 300 n mi south of Bermuda, and became a tropical storm six hours later. Gabrielle tracked northward, turned northwest briefly, passed near Bermuda, then turned north-northeast into a sheared environment and dissipated by 1800 UTC 13 September when its surface circulation fell apart.

Gabrielle did not make a direct landfall as a hurricane. As a tropical depression and disturbance, it passed close enough to affect Puerto Rico and the Dominican Republic on 4–6 September, producing rain and minor coastal inundation. The system passed about 20 nautical miles west of Hamilton, Bermuda, around 0100 UTC 11 September while at tropical-storm strength, bringing the island tropical-storm-force winds and rain.

The storm’s peak intensity was estimated at 55 knots (about 63 mph) with a minimum central pressure of 1003 mb at 1200 UTC 10 September, making its peak a moderate tropical storm. Reconnaissance later measured somewhat lower winds as the low-level center became separated from the convection.

Storm surge and rainfall were generally modest. In Puerto Rico and the U.S. Virgin Islands, measured storm surge inundations were less than 1 foot. On Bermuda, a forecaster estimated a minimal storm surge around 1 foot at St. George’s, and the Bermuda Weather Service reported 1.43 inches of rain at its office (with informal reports and radar indicating higher amounts elsewhere). A buoy south of St. Thomas recorded a 44-knot gust on 5 September, associated with a squall line rather than the cyclone’s core.

There were no reported casualties associated with Gabrielle. Impacts were limited: Bermuda experienced tropical-storm-force winds that downed tree branches and palm fronds, caused minor infrastructure damage (including a damaged dock and boat in Dockyard), and produced small power outages. Puerto Rico and the U.S. Virgin Islands saw rain and minor coastal flooding but no significant reported damage.

Noteworthy aspects include Gabrielle’s unusual life cycle — forming, weakening to a disturbance near Hispaniola, and then regenerating into a tropical cyclone days later south of Bermuda — and the temporary decoupling of its low- and mid-level centers on 5 September. Forecast track errors were below the recent 5-year mean at 12 and 24 hours but were larger at longer times; official intensity forecast errors were generally smaller than the recent 5-year mean.