Helene Intensifies to a Major Hurricane

Hurricane Helene intensified to a major hurricane over the eastern Gulf of Mexico on Thursday.  At 2:00 p.m. EDT on Thursday the center of Hurricane Helene was located at latitude 26.7°N and longitude 84.9°W which put the center about 205 miles (335 km) south of Apalachicola, Florida.  Helene was moving toward the north-northeast at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 959 mb.

A Hurricane Warning is in effect for the portion of the coast from Anclote River to Mexico Beach, Florida.

A Hurricane Watch is in effect for the portion of the coast from Anclote River to Englewood, Florida.  The Hurricane Watch includes Tampa Bay.

A Tropical Storm Warning is in effect for the portion of the coast from Anclote River to Flamingo, Florida.  The Tropical Storm Warning includes Tampa Bay.  A Tropical Storm Warning is in effect for the Lower and Middle Florida Keys west of Channel 5 Bridge.  A Tropical Storm Warning is in effect for the Dry Tortugas.  A Tropical Storm Warning is in effect for the portion of the coast from Mexico Beach to the Okaloosa/Walton County Line, Florida.  A Tropical Storm Warning is in effect for the portion of the coast from Flamingo, Florida to Little River Inlet, South Carolina.  A Tropical Storm Warning is in effect for Lake Okeechobee. 

A U.S. Air Force Hurricane Hunter aircraft found that Hurricane Helene had strengthened to a major hurricane on Thursday afternoon.  An eye with a diameter of 30 miles (48 km) was at the center of Helene’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Helene.  Storms near the center of Helene generated strong upper level divergence that pumped large quantities of mass away from the hurricane.

The circulation around Hurricane Helene was large.  Winds to hurricane force extended out 60 miles (95 km) from the center of Helene’s circulation.  Winds to tropical storm force extended out 345 miles (555 km) in the eastern side of Hurricane Helene.  Winds to tropical storm force extended out 140 miles (225 km) in the western side of Helene’s circulation.

The Hurricane Intensity Index (HII) is 22.1.  The Hurricane Size Index (HSI) is 17.6 and the Hurricane Wind Intensity Size Index (HWISI) 39.7.  Hurricane Helene is stronger than Hurricane Irma was when Irma hit southwest Florida in 2017.  However, Helene is not as big as Irma was.

Hurricane Helene will move through an environment favorable for intensification during the next few hours.  Helene will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the eastern Gulf of Mexico.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Hurricane Helene is likely to intensify during the next few hours.  Helene could strengthen to Category 4 on the Saffir-Simpson Scale.

Hurricane Helene will move around the western end of a high pressure system over the western Atlantic Ocean.  The high pressure system will steer Helene toward the north-northeast during the next 24 hours.  On its anticipated track, Hurricane Helene will make landfall on the coast of northern Florida at Apalachee Bay Thursday evening.  Helene will be a major hurricane when it reaches the coast.

Hurricane Helene will be a major hurricane when it reaches northern Florida.  Helene will be a large and dangerous hurricane.  Hurricane Helene will bring strong winds and heavy rain to northern Florida.  Heavy rain is likely to cause floods.

Flood Watches are in effect for Florida, eastern Alabama, Georgia, western South Carolina, western North Carolina and eastern Tennessee.

Helene could also cause a storm surge of up to 20 feet (6.1 meters) along portions of the west coast of Florida.

A Storm Surge Warning is in effect for the portion of the coast from Mexico Beach to Flamingo, Florida.  The Storm Surge Warning includes Tampa Bay and Charlotte Harbor.

An upper level trough over the Mississippi River Valley will steer Hurricane Helene quickly toward the north-northeast after it makes landfall.  Since the circulation around Helene is so large, Hurricane Helene will produce hurricane force winds in inland locations as well.

Hurricane Warnings are in effect for parts of northern Florida, southeastern Alabama and southwestern Georgia.  The Hurricane Warnings include Tallahassee, Florida and Macon, Georgia.

Tropical Storm Warnings are in effect for the Florida Peninsula, northwest Florida eastern Alabama, northern and eastern Georgia, all of South Carolina, southwestern North Carolina, and southeastern Tennessee.  The Tropical Storm Warnings include Atlanta, Georgia and Charleston, South Carolina.

Hurricane Helene is likely to cause widespread electricity outages as it moves inland over the southeastern U.S.