After intensifying into a hurricane on Thursday, Hurricane Hermine is making landfall near St. Marks, Florida. At midnight EDT the center of Hurricane Hermine was located at latitude 29.8°N and longitude 84.2°W which put it about 20 miles (30 km) south of St. Marks, Florida. Hermine was moving toward the north-northeast at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h). The minimum surface pressure was 984 mb.
A Hurricane Warning is in effect from Suwannee River to Mexico Beach, Florida. A Hurricane Watch is in effect from Anclote River to Suwannee River and from Mexico Beach to the Walton County/Bay County line. A Tropical Storm Warning is in effect from Englewood to Suwannee River and from Mexico Beach to the Walton County/Bay County line. A Tropical Storm Warning is also in effect from the Flagler County/Volusia County line to Duck, North Carolina including Pamlico and Albemarle Sounds. A Tropical Storm Watch is in effect from Duck, North Carolina to Sandy Hook, New Jersey including the Chesapeake Bay from Smith Point southward and southern Delaware Bay.
The circulation of Hurricane Hermine organized quickly on Thursday. It developed an eye with a mostly complete eyewall. Spiral rainbands developed with strong winds in the eastern half of the circulation. Upper level divergence to the east of Hermine pumped out mass and allowed the surface pressure to decrease. The circulation is still asymmetrical with most of the stronger winds east of the center, but it looks a lot more typical of hurricanes that move toward the northern coast of the Gulf of Mexico.
Hurricane Hermine will weaken after it makes landfall. It could interact with a cold front moving into the southeastern U.S. It is possible that Hermine could develop a hybrid structure that is part tropical and part extratropical. Hermine could have winds to tropical storm force as it passes over the Mid-Atlantic coast. The stronger winds are likely to be out over the Atlantic Ocean and winds should be weaker farther inland.
An upper level trough is steering Hurricane Hermine toward the north-northeast and a general northeasterly motion is expected to continue for another 36 hours. Later in the weekend a surface high pressure system could move north of Hermine and stall its progress. Hermine could be stationary for a time. On its anticipated track center of Hermine is likely to pass east of Tallahassee, Florida. The center could pass north of Savannah, Georgia before coming near Charleston, South Carolina. Hermine is likely to move near Cape Hatteras, North Carolina and out into the Atlantic Ocean.
Hurricane Hermine is capable of causing regional minor wind damage. It is likely to cause widespread power outages. The coast of the northeastern Gulf of Mexico is susceptible to storm surges and high water will effect that area overnight. Locally heavy rainfall will create the potential for flooding. When rainbands move ashore, wind shear could spin up tornadoes. As Hermine moves near the Mid-Atlantic coast, easterly winds could cause water rises.
The Hurricane Intensity Index (HII) for Hurricane Hermine is 11.5. The Hurricane Size Index (HSI) is 14.0. The Hurricane Wind Intensity SIze Index (HWISI) is 25.5. These indices are very similar to the ones for Hurricane Isaac before it hit the coast of Louisiana n 2012. The HII for Isaac was 11.5. Its HSI was 16.7 and its HWISI was 28.2. This means that Hurricane Hermine is as strong and just smaller than Hurricane Isaac was just before it made landfall. Hurricane Isaac did hit a more populated and more built up region. Hurricane Isaac did 970 million dollars worth of insured damage. It caused 407 million dollars to be paid out for flood insurance. It is estimated that Hurricane Isaac caused 2.35 billion dollars worth of damage in the U.S.