September 2nd, 2016

Hurricane Hermine

Posted at 11:52 AM ET

hurricane-hermine-smHurricane Hermine made landfall overnight near Saint Marks, Florida, with maximum sustained winds of 80 mph, according to the National Hurricane Center (NHC). This is the first hurricane to make landfall in Florida since Hurricane Wilma (October, 2005). Impacts under storm surge have been quite severe for some areas of the northwest Florida coast including Cedar Key. The storm has also caused downed trees and powerlines with some structural damage. The full extent of impacts from this event is still being determined as recovery and assessment efforts are still underway. Our first thoughts and concerns are with those lost and directly affected by this event.

Hermine has since weakened to a tropical storm, and Tropical Storm Hermine is expected by the NHC to move through southeast Georgia and the eastern Carolinas and move into the Atlantic on Saturday. Heavy rainfall, tropical storm force winds and tornadoes will be ongoing threats during this time.

hurricane-hermine-lgHurricane Hermine track and position reports. Source: Guy Carpenter, National Hurricane Center

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.

Once in the Atlantic, Hermine should slow while turning to the north. Hermine should strengthen due to warm waters and interaction with another frontal system. A threat to the Mid-Atlantic coast and southern New England is possible early next week.

Tropical storm warnings remain active for areas under imminent threat. A tropical storm watch now extends into Watch Hill, Rhode Island, including Long Island and New York City. Interests along the Atlantic coast from north Florida to New England should closely monitor the progress of Hermine and implement response plans as appropriate.

Meteorological Discussion

Hurricane Hermine originated from a tropical wave (elongated area of low pressure) that left the coast of Africa around August 18. Development of the feature was suppressed in an environment of dry air and robust wind shear. As the feature moved through the Caribbean, it failed to develop a closed circulation or a clear center of circulation. Nevertheless, the feature brought heavy rainfall and gusty winds to the Leeward Islands, Puerto Rico, Hispaniola, the Bahamas, Cuba and south Florida.

As the feature moved away from the Florida Keys into the eastern Gulf of Mexico, it developed a closed circulation and a more focused center, and was then classified by the National Hurricane Center (NHC) as a tropical depression at 5 p.m. EDT (21 UTC) on Sunday, August 28. The depression continued to move into the Gulf of Mexico.

Dry air and wind shear initially suppressed development of the depression, but warm waters enabled development of significant thunderstorm clusters. These clusters were able to organize and consolidate on August 30 and 31 in an environment of reduced wind shear. As maximum sustained winds reached 40 mph, the tropical depression was then classified as Tropical Storm Hermine by the NHC, at 2 p.m. EDT (18 UTC) on Wednesday August 31. Later on August 31, Hermine turned into a north-northeasterly track to follow an upper-level disturbance digging into the area from the mainland.

Hermine continued to slowly strengthen in an environment of warm waters and variable wind shear while approaching the northwest Florida coast. Following a Hurricane Hunter aerial reconnaissance mission, on Thursday, September 1, observations indicated that Hermine carried maximum sustained winds of 75 mph. Hermine was upgraded to hurricane status at 2:55 p.m. EDT (1855 UTC) on Thursday, September 1. Hermine then strengthened further to carry maximum sustained winds of 80 mph just prior to landfall on the north Florida Coast.

According to NHC advisories, Hurricane Hermine made landfall just east of Saint Marks, Florida, around 1:30 a.m. (0530 UTC) on Friday, September 2. Maximum sustained winds at landfall were reported by the NHC as 80 mph, with a central pressure of 982 millibars. Hermine passed within 25 miles of Tallahassee, Florida. Sustained winds of 52 mph and gusts to 67 mph were reported at Keaton Beach, Florida. A gust to 55 mph was reported at Perry, Florida. A storm tide of at least 7.6 feet above mean sea-level, and an unofficial storm surge of 7.5 feet were reported in Cedar Key, Florida. NWS estimated rainfall amounts of four to six inches have affected large areas of central Florida and southeast Georgia, with local amounts exceeding 22 inches reported in Lake Tarpon Canal, Florida, and 18.89 inches reported near Baskin, Florida. After landfall, Hermine weakened back to tropical storm status effective 5 a.m. EDT (09 UTC) on September 2. Hermine has since moved into southeast Georgia.

Hermine is expected by the NHC to move through South Georgia and the eastern Carolinas, and should move offshore into the Atlantic as a weak tropical storm on Saturday. Tropical storm warnings remain active, and the threat of tropical storm winds, heavy rainfall of at least five to 10 inches (and isolated amounts to 15 inches), and some tornadoes will remain for affected areas. A threat of storm surge of two to four feet will affect coastal areas of the Carolinas and the Mid-Atlantic, with a possible threat also for southern New England.

After moving into the Atlantic, Hermine should then turn to the north and slow late this weekend into next week. As Hermine interacts with another frontal system and moves over warm waters, some strengthening to strong tropical storm or weak hurricane strength is probable late in the weekend. Model guidance is in some disagreement on track into early next week and the forecast distance of the storm from the mainland remains unclear, as do resulting impacts. A landfall in the Mid-Atlantic or southern New England region is possible depending on steering currents, and tropical storm watches are active as far north as Watch Hill, Rhode Island.

Hermine may undergo extratropical transition after two days due to interaction with the frontal system. This means that the system will lose its tropical characteristics, expand in size, and resemble a nor’easter instead of a tropical cyclone. Once this transition is complete, Hermine would then be reclassified by the NHC as a post-tropical cyclone, with winds of up to 75 mph.

Regardless of NHC classification of Hermine, the NHC intends to issue tropical watches and warnings where equivalent impacts may be rendered from the post-tropical cyclone, as allowed by new protocols implemented since 2012.

Hurricane Hermine is the first hurricane to make landfall in Florida since Hurricane Wilma (2005), and the first to hit the U.S. since Hurricane Arthur (2014).

Impacts

Media reports indicate one death in Marion County when a man was hit by a tree. Storm surge impacts have been quite severe along the Taylor County coastline, including the area of Cedar Key, Florida. Inundation due to storm surge produced damage to numerous homes, storage buildings, and a 100-yard fishing pier in Dekle Beach, Florida, according to media reports. Flooding also forced 18 people from their homes in Pasco County in Green Key and Hudson Beach. Local law enforcement teams rescued people from rising water and took them to nearby shelters. Mandatory evacuations remain in place for areas including Levy County, Florida.

In Wakulla County, south of Tallahassee, Florida, local authorities reported at least seven homes damaged by falling trees. Heavy rain and strong winds left thousands of homes without power along the Florida Gulf Coast. Power outages have affected at least 253,000 and an estimated 170,000 people were without power as of Friday morning in regions affected by the storm, according to local reports. The NWS has stated that more than half of Tallahassee is without power. Thousands are reportedly without power in parts of southeast Georgia.

Further south, the Sunshine Skyway Bridge spanning Tampa Bay remained closed on Friday morning due to high winds.

Sources: Reuters, Associated Press, National Hurricane Center, National Weather Service, The Weather Channel.

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Guy Carpenter publishes CAT-i reports for major natural catastrophes worldwide. These reports cover catastrophes including worldwide tropical cyclones, earthquakes, major UK and European floods and any other natural event that is likely to incur a significant loss to the (re)insurance industry. Please email CAT.i@guycarp.com if you wish to be added to the free email distribution list.

Guy Carpenter compiles RISK-i reports for major technological or man-made events worldwide. These reports cover risks to property, transport and life including explosions, fires, crashes, engineering disasters and terrorist attacks that are likely to incur a significant loss to the (re)insurance industry. Please email RISK.i@guycarp.com if you wish to be added to the free email distribution list.

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