Hurricane Gonzalo

Pre-Landfall 1 | Summary
Posting Date: October 14, 2014, 1:30:00 PM

Tropical Storm Gonzalo passed through the eastern Caribbean on a northwest course, further east than initially forecast, delivering heavy wind and rain to Antigua and other close-by islands. Near St. Martin, Gonzalo achieved hurricane-speed winds and continued to strengthen—more quickly than forecast. Now a Category 2 storm with 110 mph maximum sustained winds and a minimum pressure of 973 mb, Gonzalo is expected to take a turn to the northeast by early Thursday and set a course for Bermuda. Hurricane Gonzalo is not expected to reach the U.S. mainland.

Satellite image of Hurricane Gonzalo late Monday, October 13. (Source: NOAA)

Many warnings and watches have been issued for Gonzalo, including hurricane warnings for Anguilla, the British Virgin Islands, and St. Martin; hurricane watches for Culebra, Puerto Rico, the U.S. Virgin Islands, and Vieques; and tropical storm warnings for Antigua, Barbuda, Culebra, Montserrat, Nevis, Puerto Rico, Saba, St. Barthelemy, St. Eustatius, St. Kitts, the U.S. Virgin Islands, and Vieques.

Meteorological Summary and Forecast

Tropical Storm Gonzalo formed over the weekend, just east of the Antilles. As a tropical storm, Gonzalo passed through the northern Antilles. As it moved northwest on Monday, roughly between Antigua and St. Thomas, Gonzalo reached hurricane status. Hurricane Gonzalo has continued to strengthen to a Category 2 storm on the Saffir-Simpson scale, with maximum sustained wind of 110 mph and a minimum pressure of 973 mb. The storm should experience lower wind shear and warm water on its projected track, contributing to its strength and potential for damage should it impact Bermuda.

Hurricane Gonzalo five-day forecast cone, as of 11:00 a.m. EDT, October 14. (Source: NOAA)

Reported and Expected Impacts

As a tropical storm and then hurricane, Gonzalo tore roofs off structures, felled trees, and knocked out power as it passed through the eastern Caribbean, primarily impacting Antigua. Heavy rain from the storm could result in mudslides, particularly in mountainous areas, as well as flash flooding. Gonzalo has also produced large swells, resulting in potentially dangerous surf and rip currents.

At Category 2 wind speeds, it is expected that significant damage will occur to poorly built structures. Structures that are built to the local codes and building standards are not immune from damage, but damage will likely be limited to roof covering, wall cladding, and unprotected windows. Similar damage would also be expected for larger commercial structures. While Bermuda is on track to experience Gonzalo’s significant winds, the high building standards and construction quality will help to mitigate much of the impact. Certainly cruise ship arrivals, air traffic, and other tourism activities would be affected.

Exposure at Risk

The potential for structural damage from hurricanes in the Caribbean region varies widely from moderate to high vulnerability, depending both on building codes and building code enforcement. Grenada, Haiti, Trinidad and Tobago, St. Lucia, St. Kitts and Nevis, Jamaica, and Barbados islands, for example, have low building regulation enforcement and thus higher vulnerability to hurricane wind and rain. In contrast, Bermuda (as well as the Bahamas and Puerto Rico), benefits from strong building codes and rigorous enforcement, and thus has lower vulnerability.

Reinforced concrete apartments, condominiums, and other structures often are constructed with some level of structural engineering attention, which reduces their vulnerability to moderate winds. However, unprotected windows and openings can pose a risk for possible breaches in the building’s envelope, subsequently allowing for higher wind loads on the building and allowing rain intrusion to damage contents. Structures of masonry construction, however, can exhibit varying vulnerability due to differences in building quality and adherence to building codes.

The AIR tropical cyclone team will continue to monitor Hurricane Gonzalo, as well as a developing storm in the Central Pacific, Tropical Storm Ana, which has the potential to affect Hawaii this weekend. Updates will be provided as warranted by events.

Pre-Landfall 1 | Downloads
Posting Date: October 14, 2014, 1:30:00 PM