Hurricane Gonzalo

Post Landfall 1 | Summary
Posting Date: October 22, 2014, 10:45:00 AM

AIR Worldwide estimates that insured losses in Bermuda from Hurricane Gonzalo will range between USD 200 million and USD 400 million. To produce loss estimates for Hurricane Gonzalo using the AIR Tropical Cyclone Model for the Caribbean, AIR used track and intensity information from NHC advisories, vortex reports from hurricane hunter aircraft, and actual wind observations from stations in Bermuda.

Gonzalo Causes Damage from the Caribbean to Scotland

After forming on October 12 east of the Antilles, Hurricane Gonzalo barreled into the Northern Antilles with winds reaching 88 mph, causing injuries and fatalities, property damage, business interruption to several cruise lines, and power outages. Several Caribbean islands were affected; particularly hard hit areas included Antigua, St. Maarten, St. Martin, and the Leeward Islands. 

On Friday October 17, at 8:30 PM AST (Atlantic Standard Time), the very center of Gonzalo made landfall on the south-central coast of Bermuda. Gonzalo’s very large, 30-mile radius eye engulfed Bermuda; webcams on the island recorded an eerie calm for about 90 minutes before strong winds, coming this time from the opposite (westerly) direction, moved in once again. When the eye began to come onshore, the storm was still a Category 3 hurricane with 115 mph sustained winds. However, by the time the center passed overhead, Gonzalo had weakened to a Category 2 hurricane, with 110 mph sustained winds.

The strongest observed winds at Bermuda International Airport were 93 mph sustained, with gusts of 113 mph. A station nearly 300 feet above sea level in Commissioner's Point reported a gust of 144 mph; however, it should be noted that winds at this elevation can be up to 30% higher than locations at sea level. The storm weakened prior to landfall due to both lower sea surface temperatures and higher wind shear in the vicinity of Bermuda. Note that the center of Tropical Storm Fay passed directly over the island less than a week ago. It is likely that Fay’s passage reduced the sea surface temperatures around Bermuda, allowing Gonzalo to be just slightly weaker than it might have been otherwise.

In 2003, Hurricane Fabian tracked just west of the island, with winds slightly higher than those from Gonzalo, causing losses of about USD 300 million (2003 USD values); AIR estimates that a recurrence of Fabian today—with today’s exposures—would result in insured losses of around USD 650 million.

After passing across Bermuda, Hurricane Gonzalo tracked in a northeasterly direction towards Newfoundland, Canada. The storm remained well offshore but produced tropical storm conditions in Newfoundland on Sunday, October 19, with high surf and heavy precipitation. On Tuesday, October 21, the hurricane’s remnants battered northern Scotland. Torrential rain and gusts reaching 70 mph proved fatal as well as damaging by downing trees. The storm also caused significant traffic and airline delays in Britain.

Damage in Bermuda

Bermuda’s building codes, which are strictly enforced, provide building design criteria to withstand sustained wind speeds up to 110 mph and gusts up to 150 mph. Buildings are usually made of reinforced masonry or concrete, and tend to have smaller windows equipped with shutters. Older more traditional buildings are often made of limestone blocks. Light metal, which is highly vulnerable to wind damage, is used mostly for warehouses or repair shops and these may not meet code requirements.

Roofs are typically made of limestone tiles cemented together. Roofs made of other materials, such as wood or asphalt shingles, and occasionally foam roofing, showed heavier damage than more traditional roofs. Roof damage increases the likelihood of structural breaches, which can then lead to damage to interior walls and finishes, as well as contents.

Most of the newer and well-maintained buildings that meet Bermuda’s codes stood up well to Gonzalo’s winds, with only minor damage to roof areas that were directly exposed to the oncoming storm. Gonzalo’s track may have also mitigated the damage in Bermuda. Building damage from winds is due to both wind speed and duration. Thus, the damage caused by Gonzalo was not as bad as it potentially could have been because Gonzalo’s eye (the calm of the storm) enveloped the entire territory as it passed directly overhead, thereby reducing the amount of time buildings were exposed to heavy winds (read more on that here).

Other damage mechanisms included damage due to flying debris. In addition, boats were torn from their moorings and subsequently left to drift freely, causing them to collide with other boats or run aground. Some boats that were housed onshore for repair or storage were blown onto their sides. High waves damaged piers and caused some coastal erosion.

AIR’s Damage Survey

AIR conducted a damage survey across Bermuda on October 19-20. In the areas surveyed, damage was mostly limited to roofs but structural damage was seen on older buildings, including some historical ones. Most resorts on the island withstood the storm very well, sustaining only minor roof damage to one or two units that were more directly exposed to high winds.

Some roof damage caused by Tropical Storm Fay a week earlier was still under repair when Hurricane Gonzalo struck. Roof damage ranged from superficial, with just a few tiles removed, to severe—although in most cases, the interiors were not breached.

Roof damage to a well-maintained residence (left) and to a building with non-Bermuda style construction (right)

Less common, but still seen in several areas, was heavier damage to older buildings or to buildings that were less well maintained or not subject to strict building codes (such as warehouses or garages).

One of the historical Cooperage buildings in Dockyard sustained extensive contents damage when a door collapsed

Warehouses and repair shops made of light metal sustained heavy damage, often resulting in damage to the contents within

Other Impacts

Gonzalo disrupted air travel, forcing flight cancellations. Additional flights were added to schedules in advance of the storm to accommodate visitors and residents who wished to leave. The Causeway, which provides access to the Bermuda International Airport from several parishes, was damaged and closed to traffic on October 17 but has since reopened—initially as a single lane.  However, on October 18, many other roads were still impassable due to fallen trees and other debris. Ferry traffic, which had been suspended, has been restored and cruise ship itineraries have since been recovered.

According to the Bermuda Electric Light Company (BELCO), Hurricane Gonzalo took out power to more than 31,000 homes; however, as of Tuesday October 21, all but around 3,000 have had their power restored. About 1,500 homes were still without power before Gonzalo struck due to Tropical Storm Fay, which cut power to nearly the entire population a week earlier.

Roof damage to a utility building at the Bermuda Electric Light Company (BELCO)

These and other photos and commentary from AIR’s damage survey on Bermuda will be made available in an Image Gallery on the AIR website in the coming weeks.

Post Landfall 1 | Downloads
Posting Date: October 22, 2014, 10:45:00 AM