Hurricane Irma - Update

Hurricane Irma was a large and destructive storm that rendered impacts to most of the Southeast United States including the Florida Keys as well as areas of the Caribbean. Impacts for areas of the Northern Leeward Islands and the Virgin Islands, as well as northern Cuba have been especially severe. For the United States, the most severe impacts have been in the Florida Keys due to both wind and storm surge, with flood impacts as far away as coastal Georgia and northeast Florida. Wind impacts extend from Tennessee to the Carolinas to Florida. At least 67 fatalities have been reported. It will take time to fully assess the full scope and severity of this ongoing event, and our first thoughts and concerns are with those directly affected.

Irma is the first major hurricane to make Florida landfall since Hurricane Wilma (2005), and the first Category 4 hurricane to affect Florida since Hurricane Charley (2004). Irma also stands with the four strongest hurricanes in the Atlantic basin, with maximum sustained winds as high as 185 mph.

Hurricane Irma track and estimated winds. Source: Guy Carpenter, NOAA/NHC

Hazard data illustrated in the CAT-i map was taken from GC AdvantagePoint®, Guy Carpenter’s web-based risk management platform. GC AdvantagePoint users can view impacted areas on any map as well as see how their portfolios were affected. Please contact your broker or cat modeling analyst for further information.

Meteorological Discussion
Advisories on Irma were first initiated by the National Hurricane Center when the feature was about 420 miles west of the Cabo Verde Islands in the East Atlantic. Irma was first classified as a tropical storm on August 30. After a period of rapid intensification over warm waters with low wind shear, Irma was rapidly upgraded to a hurricane on August 31 with 100 mph winds. A few days later on September 5, while approaching the Leeward Islands, Irma gained intensity to become a rare Category 5 hurricane, and became one of only four hurricanes in North Atlantic Basin history to reach maximum sustained winds of 185 mph or more. Irma then crossed the Leeward Islands and Caribbean to render especially severe impacts.

Irma then passed just north of Puerto Rico and Hispaniola, before grazing the northern coast of Cuba as a Category 5 hurricane. Irma weakened to a Category 3 hurricane while interacting with the land and topography of Cuba, while rendering severe impacts.

While approaching and crossing the northern coast of Cuba, Irma followed the southern edge of the Atlantic subtropical ridge, which suppresses the northward motion of hurricanes. Irma eventually turned once it had reached the western edge of this feature. The placement and timing of Irma's turn along this edge, which was also influenced by another weather system moving from the U.S. mainland, was very difficult to determine. This produced considerable spread in model guidance and resulting forecast uncertainty. Irma made the turn later than initially expected, resulting in a track that was further west.

After turning north from Cuba toward the Florida Keys, Irma was able to regain intensity as a Category 4 hurricane. Irma made landfall on Cudjoe Key, Florida, the morning of September 10, with maximum sustained winds of 130 mph, a Category 4 hurricane on the Saffir-Simpson Scale. Irma is the first Category 4 hurricane to affect Florida since Hurricane Charley (2004), and the first major hurricane (Category 3 or higher) to make Florida landfall since Hurricane Wilma (2005). Severe impacts due to wind and storm surge were rendered to areas of the Florida Keys.

Irma then moved away from the Florida Keys toward the southwest Florida coast. Irma made final landfall on Marco Island the afternoon of September 10, with maximum sustained winds of 115 mph, a Category 3 hurricane on the Saffir-Simpson Scale. Irma then moved along the western Florida Peninsula, while weakening rapidly due to land interaction and increasing wind shear. Irma was downgraded to tropical storm status on September 11 before crossing into South Georgia, and then to tropical depression status late on September 11.

Irma affected Florida as a very large storm, with extent of tropical storm winds reaching 415 miles from the center of circulation. Wind impacts were experienced over a very large area of the Southeast as a result. Irma also produced heavy rainfall over large areas of the Southeast to produce both flood and flash-flood impacts. The large wind footprint also allowed the development of a significant storm surge that affected areas of northeast Florida and coastal Georgia including Saint Augustine and Jacksonville, in addition to the southern Florida Peninsula and Florida Keys. The wind direction and track of Irma caused seawater to be pushed out of Tampa Bay for a period of time, lessening the severity of the expected storm surge. Heavy rainfall in northeast Florida coupled with storm surge also produced flooding in areas adjacent to the Saint Johns River and surrounding watersheds.

Key dates for Hurricane Irma are listed below, following advisories of the NHC.

• 11 a.m. EDT, August 30, 2017 - Advisories initiated on Tropical Storm Irma by the NHC. Maximum sustained winds 50 mph. Central pressure 1004 millibars (mb).
• 11 a.m. EDT, August 31 - Irma upgraded to hurricane status by the NHC, with maximum sustained winds of 100 mph. Central pressure 979 mb. Rapid intensification.
• 5 p.m. EDT, September 1 - Irma becomes a major hurricane. Maximum sustained winds 120 mph. Central pressure 964 mb.
• 5 p.m. EDT, September 3 - Hurricane watches issued by the NHC for portions of the Leeward Islands. Maximum sustained winds 115 mph. Central pressure 969 mb.
• 5 p.m. EDT, September 4 - Irma becomes a Category 4 hurricane on the Saffir-Simpson Scale. Maximum sustained winds 130 mph. Central pressure 944 mb.
• 7:45 a.m. EDT, September 5 - Irma becomes a Category 5 hurricane on the Saffir-Simpson Scale. Maximum sustained winds 175 mph. Central pressure 929 mb. Increased winds found with aircraft reconnaissance. Irma approaches the Leeward Islands.
• 2 p.m. EDT, September 5 - Irma gains maximum sustained winds of 185 mph. Central pressure 926 mb. Irma is one of only four hurricanes in the Atlantic basin to have maximum sustained winds of 185 mph or more. Irma approaches the Leeward Islands.
• September 6 - Core of Irma passes over Barbuda, St. Martin and Virgin Islands, with especially severe impacts. Irma passes north of Puerto Rico
• September 7 - Core of Irma passes north of Hispaniola.
• 11 a.m. EDT, September 7 - Hurricane watches issued by NHC for certain areas of South Florida and Florida Keys. Core of Irma approaches Turks and Caicos Islands. Maximum sustained winds 175 mph. Central pressure 921 mb.
• 11 p.m. EDT, September 7 - Hurricane warnings issued for South Florida and Florida Keys. Irma moves near Turks and Caicos Islands. Maximum sustained winds 175 mph. Central pressure 919 mb.
• 5 a.m. EDT, September 8 - Irma becomes a Category 4 hurricane. Maximum sustained winds 155 mph. Central pressure 925 mb.
• 8 p.m. EDT, September 8 - Irma's southwestern eyewall moves over northern coast of Cuba. Maximum sustained winds 155 mph. Central pressure 924 mb.
• 11 p.m. EDT, September 8 - Irma makes landfall on the Camaguey Archipelago of Cuba as a Category 5 hurricane on the Saffir-Simpson Scale. Maximum sustained winds 160 mph. Central pressure 924 mb.
• September 9 - Irma weakens to a Category 3 hurricane due to land and topography interaction while moving along the northern coast of Cuba.
• 2 a.m. EDT, September 10 - Irma regains status as a Category 4 hurricane. Irma has turned to the northwest and is moving away from Cuba and toward the Florida Keys. Maximum sustained winds 130 mph. Central pressure 931 mb.
• 9:10 a.m. EDT, September 10 - Irma makes landfall near Cudjoe Key, Florida, about 20 miles east-northeast of Key West, Florida. Irma is a Category 4 hurricane, and the first Category 4 to make Florida landfall since Hurricane Charley (2004). Maximum sustained winds 130 mph. Central pressure 929 mb.
• 11 a.m. EDT, September 10 - Irma shows first signs of weakening while approaching the southwest Florida coast due to wind shear and land interaction. Maximum sustained winds 130 mph. Central pressure 933 mb.
• 2 p.m. EDT, September 10 - Irma weakens to a Category 3 hurricane while the core approaches southwest Florida. Irma affects much of South Florida. Maximum sustained winds 120 mph. Central pressure 936 mb.
• 3:35 p.m. EDT, September 10 -Irma makes final landfall at Marco Island, Florida. Irma is a Category 3 hurricane on the Saffir-Simpson Scale. Maximum sustained winds 115 mph. Central pressure 940 mb. The core of Irma moves inland along the western Florida Peninsula.
• 5 p.m. EDT, September 10 - Irma weakens to a Category 2 hurricane on the Saffir-Simpson Scale with the core passing five miles north of Naples, Florida. Maximum sustained winds 110 mph. Central pressure 938 mb. The core of Irma continues moving inland along the western Florida Peninsula.
• 11 p.m. EDT, September 10 -The wind field of Irma has expanded significantly. Hurricane and tropical storm force winds extend outward from the center to 80 and 415 miles, respectively. The center of Irma passes 40 miles east-northeast of Sarasota, Florida. Maximum sustained winds 100 mph. Central pressure 952 mb.
• 2 a.m. EDT, September 11 -Irma weakens to a Category 1 hurricane on the Saffir-Simpson Scale while passing 20 miles northwest of Lakeland, Florida. Maximum sustained winds 85 mph. Central pressure 960 mb. The core of Irma continues moving inland along the western Florida Peninsula while weakening rapidly due to land interaction and wind shear.
• 5 a.m. EDT, September 11 -Irma passes 35 miles east-southeast of Cedar Key, Florida. Irma is now a minimal hurricane. Maximum sustained winds 75 mph. Central pressure 965 mb. The core of Irma continues moving inland along the western Florida Peninsula while weakening rapidly due to land interaction and wind shear.
• 8 a.m. EDT, September 11 -Irma downgraded by the NHC to a tropical storm. Hurricane warnings are discontinued by the NHC, but tropical storm warnings are retained for areas of Florida, Georgia and South Carolina. Irma is still a very large storm with the center located about 30 miles north-northeast of Cedar Key, Florida. Maximum sustained winds 70 mph. Central pressure 970 mb. Irma continues to weaken.
• 2 p.m. EDT, September 11 - The center of Irma moves into South Georgia and passes about 50 miles south-southeast of Albany, Georgia. Maximum sustained winds 60 mph. Central pressure 980 mb. Irma continues to weaken.
• 5 p.m. EDT, September 11 - Tropical storm warnings are discontinued by the NHC for the state of Florida, but remain active for areas of Georgia and South Carolina. The center of Irma continues moving through South Georgia. Irma retains status as a very large storm. Maximum sustained winds 50 mph. Central pressure 985 mb. Irma continues to weaken.
• 11 p.m. EDT, September 11 - Irma is downgraded by the NHC from a tropical storm to a tropical depression. All remaining tropical storm warnings are discontinued by the NHC. Maximum sustained winds 35 mph. Central pressure 988 mb. Irma continues to degrade and weaken.
• 5 a.m. EDT, September 12 - Irma has transformed its structure into a frontal system instead of a tropical cyclone. Irma is reclassified as a post-tropical cyclone (with winds below equivalent tropical-storm strength). Maximum sustained winds 25 mph. Central pressure of 998 mb. The center of Irma passes about 65 miles southwest of Atlanta Georgia.

Selected unofficial peak wind gust reports for Irma include:
(National Weather Service)

• Near Naples - 142 mph (FL)
• Near Marco Island - 130 mph (FL)
• Near Big Pine Key - 120 mph (FL)
• Near Miami International Airport - 99 mph (FL)
• Southwest Florida International Airport - 89 mph (FL)
• Mayport NAS - 87 mph (FL)
• Jacksonville International Airport - 86 mph (FL)
• Fort Myers FAA/AP - 84 mph (FL)
• Fort Pulaski - 70 mph (GA)
• Near Tybee Island - 65 mph (GA)
• Hartsfield Atlanta International Airport - 64 mph (GA)
• Columbus Airport - 53 mph (GA)
• Near Highlands - 56 mph (NC)
• Charlotte Douglas International Airport - 45 mph (NC)
• Near Parris Island - 76 mph (SC)
• Folly Beach - 72 mph (SC)
• Beaufort - 66 mph (SC)
• Clingman's Dome Tower - 66 mph (TN)
• Near Gatlinburg - 60 mph (TN)
• Near Chattanooga - 45 mph (TN)
• Troy Municipal Airport - 45 mph (AL)
• Montgomery Regional Airport - 40 mph (AL)

Selected unofficial rainfall totals for Irma include:
(National Weather Service)

• Ft. Pierce/St. Lucie County International Airport - 15.91 inches (FL)
• Oviedo - 14.76 inches (FL)
• Naples - 11.87 Inches (FL)
• National Key Deer NWR - 11.74 inches (FL)
• West Melbourne - 11.21 inches (FL)
• Fort Myers International Airport - 10.33 inches (FL)
• Fort Lauderdale Exec. Airport - 9.57 inches (FL)
• Orlando/Sanford Airport - 9.42 inches (FL)
• West Point - 4.70 inches (AL)
• Saint Mary's River near Kingsland - 10.12 inches (GA)
• Homeland - 9.18 inches (GA)
• Savannah/Hunter AAF - 6.88 inches (GA)
• Busick - 6.05 inches (NC)
• Near Charleston - 8.65 inches (SC)
• Charleston Weather Forecast Office - 6.18 inches (SC)

Additional wind and reports can be found from the U.S. Weather Prediction Center.
Selected unofficial water heights above mean lower-low water in Florida:
(National Ocean Service)

• Fernandina Beach - 10.2 feet
• Mayport (Bar Pilots Dock) - 8.6 feet
• Trident Pier, Port Canaveral - 8.1 feet
• Virginia Key, Biscayne Bay - 5.9 feet
• Vaca Key, Florida Bay - 3.5 feet
• Naples, Gulf of Mexico - 7.1 feet
• Fort Myers, Caloosahatchee River - 4.6 feet
• Old Port Tampa - 3.7 feet
• Saint Petersburg, Tampa Bay - 3.4 feet
• Cedar Key - 5.0 feet

Impacts
Media reports indicate at least 67 fatalities as a result of Hurricane Irma in the Caribbean and Southeast United States, with 31 reported deaths in Florida, Georgia and South Carolina.  As reported earlier by media, AIR Worldwide estimates insured losses from Irma for the United States between USD 20 billion to USD 40 billion. These loss estimates include impacts from wind and storm surge and time element coverage but do not include losses rendered to the National Flood Insurance Program, losses to uninsured properties, losses to inland marine, marine cargo and hull and pleasure boats, and losses to infrastructure. RMS estimates that there is a 10 percent chance of insured wind losses from Irma exceeding USD 60 billion. The estimate does not include contributions from storm surge or post-event loss amplification.

Caribbean
As discussed in the last report, impacts for certain areas of the Caribbean have been especially severe, according to media reports. Water and food supplies for the most severely affected areas are compromised and limited, and power outages remain. In the U.S. Virgin Islands, FEMA and the U.S. military are helping to rescue those still trapped in their homes blocked by debris, although the local water and power authority reports that several feeders on St. Thomas have been re-energized. Meanwhile in the territories of St. Barts and St. Martin, 2,000 troops have been deployed the French Government to support security and restoration efforts. Meanwhile in Anguilla, additional finds have been secured by the British Government to support relief efforts. Meanwhile the Dutch Red Cross still reports more than 200 missing from St. Maarten, where one third of buildings were destroyed and 90 percent damaged, according to media reports. In Puerto Rico, the U.S. Department of Energy reports at least 303,998 without power as of Wednesday morning.

Florida
In Florida, media reports indicate that at least USD 250 million has already been spent on preparation and recovery efforts. Over 3.5 million customers remain without power, accounting for at least 35 percent of total state customers, according to the U.S. Department of Energy. Estimates indicate that restoration for the Florida west coast may occur by September 22, and most of the east coast by September 17. Reports also indicate that fruit and agricultural damage may be significant including impacts to citrus, sugar cane and vegetable crops. Several ports were expected to reopen Wednesday including Port Everglades, Jacksonville and Tampa. Most major airports have re-opened; however, power outages are impeding recovery efforts according to media reports.

Meanwhile in the Florida Keys, media reports indicate at least 25 percent of homes were destroyed according to FEMA estimates, while 65 percent sustained major damage, although reports from local officials indicate that these numbers may be lower.

Inundation impacts to otherwise well-constructed homes may be difficult to discern in the meantime. Residents have been allowed to return to the Upper Keys including Key Largo and Islamorada. Meanwhile, crews have been working to repair two sections of US-1 that have been washed out. Efforts to assess the 42 bridges that link the islands indicate these bridges are now safe, according to media reports. The U.S. Navy has deployed three large assets including the USS Abraham Lincoln to support search and rescue and recovery efforts. Areas remain without power, water and communications service, according to media reports. Most gas stations in Key Largo remain closed. Meanwhile in Monroe County, a dusk-to-dawn curfew has been declared by local authorities.

Further north in Jacksonville, evacuation orders have been lifted after 350 water rescues were conducted across the city. Media reports indicate the worst damage in the downtown, Riverside and San Marco neighborhoods.

In the Marco Island/Naples area, city officials have completed damage assessments and estimate that it suffered at least USD 100 million in damage. Residents were scheduled to return home on Tuesday following debris removal efforts in the area. Streets in the area remain blocked due to downed power lines. Officials in Marco Island indicate that parts of the island suffered one to two feet of standing water following Irma's passage, after an estimated storm surge of three to four feet.

In Orlando, downed trees and powerlines were found throughout the city Tuesday. The airport has resumed some flights. Walt Disney World was scheduled to reopen Tuesday, and media reports indicate only minimal damage.

In the Miami/Fort Lauderdale area, schools are closed. The University of Miami will resume classes Monday. Florida International University and Miami-Dade College have been closed until further notice, according to media reports. A downed crane caused evacuations of two adjacent buildings. Media reports indicate that Miami police arrested more than 50 suspected looters, including 26 people who broke into a single Walmart store. Miami Beach residents were allowed to return home Tuesday. Miami International and Fort Lauderdale Airports resumed operations Tuesday, but with reduced capacity. Miami airport expects to resume full capacity by the weekend, according to media reports.

In the Tampa/Saint-Petersburg area, reports indicate hundreds of downed trees and powerlines that blocked roads. Power outages affected hundreds of thousands. Gas station canopies were torn. Local flooding was reported in area streets. A roof was also torn from a Madeira Beach apartment. At the Saint Petersburg Marina, six boats sank and one was lodged under a dock. Reports indicate about 300 traffic lights that were out as of Tuesday morning in Pinellas County. Tampa International Airport resumed operations Tuesday, and was expecting to return to full schedule today. Residents were allowed to return to Pinellas County Monday morning, according to media reports.

Georgia
Media reports indicate that a bridge in Savannah and another in Brunswick were deemed impassable by state officials. At least three fatalities were reported in the state, including one woman who died when a tree collapsed on her vehicle. At least 500,000 residents were without power, or eleven percent of state customers, according to the U.S. Department of Energy. Meanwhile, media reports indicate that flooding has caused closure of Glynn County until further notice.

South Carolina
Media reports indicate at least four fatalities as a result of the storm. The U.S. Department of Energy reports at least 60,000 customers without power as of Wednesday morning.
North Carolina

The U.S. Department of Energy reports at least 27,629 customers without power as of Wednesday morning.

Sources: Reuters, Associated Press, U.S. National Hurricane Center, U.S. National Weather Service, The Weather Channel, U.S. Department of Energy, AIR Worldwide, Risk Management Solutions, CoreLogic

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