Tag Archives: Charleston

Tropical Depression Four Strengthens to Tropical Storm Danny

Former Tropical Depression Four strengthened to Tropical Storm Danny near the coast of South Carolina on Monday afternoon. At 3:00 p.m. EDT on Monday the center of Tropical Storm Danny was located at latitude 32.2°N and longitude 79.7°W which put it about 45 miles (75 km) south-southeast of Charleston, South Carolina. Danny was moving toward the west-northwest at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1014 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Edisto Beach to South Santee River, South Carolina. The Tropical Storm Warning included Charleston.

Based on data from weather radar and a reconnaissance plane, the National Hurricane Center determined that former Tropical Depression Four had strengthened to Tropical Storm Danny on Monday afternoon. Thunderstorms formed near the center of Danny, when the center moved over the warmer water in the Gulf Stream. Downdrafts in the thunderstorms transported stronger winds to the surface and former Tropical Depression Four intensified into Tropical Storm Danny. The thunderstorms were occurring in the western half of Danny. Bands in the eastern half of the tropical storm consisted primarily of showers and lower clouds

Tropical Storm Danny will move through an environment that is slightly favorable for intensification during the next few hours. Danny will move over water where the Sea Surface Temperatures are near 27°C. An upper level low centered over Northwest Florida will produce easterly winds that will blow toward the top of the tropical storm. Those winds will cause vertical wind shear that will inhibit intensification. However, the shear does not appear to be strong enough to prevent intensification. Tropical Storm Danny could get a little stronger during the next few hours.

Tropical Storm Danny will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer Danny toward the west-northwest. On its anticipated track the center of Tropical Storm Danny could make landfall near Edisto Beach, South Carolina on Monday night. Danny will produce gusty winds along the coast of South Carolina. It could also drop locally heavy rain over parts of southern South Carolina and extreme eastern Georgia.

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Tropical Depression Four Forms, Tropical Storm Warning for South Carolina

Tropical Depression Four formed on Monday morning and the National Hurricane Center issued a Tropical Storm Warning for a portion of the coast of South Carolina. At 11:00 a.m. EDT on Monday the center of Tropical Depression Four was located at latitude 31.9°N and longitude 78.3°W which put it about 110 miles (175 km) east-southeast of Charleston, South Carolina. Tropical Depression Four was moving toward the west-northwest at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1013 mb.

A Tropical Storm Warning was issued for the portion of the coast from Edisto Beach to South Santee River, South Carolina. The Tropical Storm Warning included Charleston.

The National Hurricane Center designated a low pressure system off the coast of South Carolina as Tropical Depression Four on Monday morning. Bands of showers and lower clouds were revolving around the center of Tropical Depression Four. Thunderstorms were occurring in bands on the far western side of the circulation around the depression. An upper low was centered over northern Florida on Monday morning. The upper low was producing easterly winds that were blowing across the top of the tropical depression. The easterly winds were causing moderate vertical wind shear and the wind shear was blowing the tops off clouds in many of the bands closer to the center of the depression

Tropical Depression Four will move through an environment that is only slightly favorable for intensification during the next 12 hours. The depression will move over water where the Sea Surface Temperatures are near 27°C. The upper level low will continue to cause vertical wind shear that will inhibit the formation of thunderstorms near the center of Tropical Depression Four. If the wind shear decreases, then there is a chance Tropical Depression Four could strengthen to a tropical storm later on Monday.

Tropical Depression Four will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer the depression toward the west-northwest. On its anticipated track the center of Tropical Depression Four could make landfall near Edisto Beach, South Carolina on Monday night. The depression will produce gusty winds along the coast of South Carolina. It could also drop locally heavy rain over parts of southern South Carolina and extreme eastern Georgia.

Low Pressure System Approaches Southeast U.S.

A surface low pressure system that developed under the eastern side of an upper level low was approaching the southeastern U.S. on Monday morning. At 8:00 a.m. EDT on Monday the center of the low pressure system which was designated as Invest 96L was located at latitude 31.6°N and longitude 77.6°W which put it about 140 miles (220 km) southeast of Charleston, South Carolina. The low pressure system was moving toward the west-northwest at 17 m.p.h. (28 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1013 mb.

A surface low pressure system formed over the Atlantic Ocean near the southeastern U.S. under the eastern side of an upper level low on Sunday. The surface low pressure system was clearly evident in visible satellite imagery on Monday morning. Bands of showers and lower clouds were revolving around the center of the surface low. Thunderstorms were occurring in bands on the far western side of the circulation around the surface low. The upper low was centered over northern Florida on Monday morning. It was producing easterly winds that were blowing across the top of the surface low. The easterly winds were causing moderate vertical wind shear and the wind shear was blowing the tops off clouds in many of the bands closer to the center of the surface low.

The surface low will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer the surface low toward the west-northwest. On its anticipated track the center of the surface low will reach the coast near the border between Georgia and South Carolina on Monday evening. The low pressure system could bring gusty winds and locally heavy rain to the areas around Savannah, Georgia and Hilton Head Island, South Carolina.

If thunderstorms develop near the center of the surface low, the National Hurricane Center could designate the system as a tropical depression or a tropical storm. If the low pressure system strengthens, then a Tropical Storm Watch or Tropical Storm Warning could be issued for a portion of the coast. A reconnaissance plane is tentatively scheduled to investigate the low pressure system on Monday afternoon, if necessary.

Potential Tropical Development Near East Coast of U.S.

There is the potential for the development of a tropical cyclone near the East Coast of the U.S. during the next several days.  A low pressure system, currently designated as Invest 98L developed over the northern Gulf of Mexico during the weekend.  The low moved slowly toward the northeast across the southeastern U.S.  At 2:00 a.m. EDT on Wednesday the low level center of Invest 98L was located at latitude 33.3°N and longitude 80.5°W which put it about 25 miles (40 km) west of Charleston, South Carolina.  The low was moving toward the east at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1013 mb.

Invest 98L currently consists primarily of a lower level circulation.  Much of the circulation is over land and the center is west of Charleston, South Carolina.  Many of the bands revolving around the center of the low pressure system consist of showers and lower clouds.  There are bands of showers and thunderstorms on the far eastern edge of the circulation which is over the Gulf Stream.  An upper level trough over the southeastern U.S. is producing westerly winds which are blowing across the top of the low level circulation.

Invest 98L will move into an environment more favorable for the development of a tropical cyclone.  It will move over water where the Sea Surface Temperature is near 27°C when the center moves over the Atlantic Ocean.  The upper level trough will over the southeastern U.S. will cause moderate vertical wind shear.  The wind shear will inhibit development.  If thunderstorms develop closer to the center of circulation, those storms could cause the circulation grow vertically into the middle and upper troposphere.  If the thunderstorms release enough latent energy in the middle and upper troposphere, a warm core could form and Invest 98L could become a tropical cyclone.

The National Hurricane Center indicated in the 8:00 a.m. EDT Tropical Weather Outlook on Wednesday that the probability was 70% that a tropical or subtropical cyclone could form during the next five days.  An upper level trough approaching the eastern U.S. will steer the low pressure system toward the north-northeast during the next few days.  On its anticipated track the low pressure system will move near the East Coast of the U.S.  A reconnaissance aircraft is tentatively scheduled to investigate Invest 98L later on Wednesday, if necessary.

Tropical Storm Bertha Brings Wind and Rain to the Carolinas

Tropical Storm Bertha brought wind and rain to the Carolinas on Wednesday.  Bertha weakened to a tropical depression after it moved inland on Wednesday afternoon.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Bertha was located at latitude 36.0°N and longitude 80.5°W which put it about 40 miles (65 km) west of Greensboro, North Carolina.  Bertha was moving toward the north at 23 m.p.h. (37 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h.  (65 km/h).  The minimum surface pressure was 1009 mb.

Flash Flood Watches were in effect for northeast South Carolina, southern and west central North Carolina, southwest Virginia and southwest West Virginia.

Tropical Storm Bertha developed rapidly on Wednesday morning and it was still strengthening when it made landfall on the coast of South Carolina.  The center of Bertha officially made landfall east of Charleston near Mount Pleasant around midday on Wednesday.  NOAA buoy 41004 which is located southeast of Charleston measured a sustained wind speed of 40 m.p.h (65 km/h) and a gust of 58 m.p.h. (94 km/h).  NOAA buoy 41029 (Capers Nearshore) measured a surface pressure of 1005.8 mb when the center of Bertha passed near it.

A weather station at Shaw Air Force Base measured 2.00 inches (51 mm)  of rain.  A weather station in downtown Charleston, South Carolina measured 1.61 inches (41 mm).  Charlotte, North Carolina received 1.64 inches (42 mm), Greensboro received 1.09 inches (28 mm) and Winston Salem received 1.04 inches (26 mm).

Tropical Depression Bertha will move around the western end of a surface high pressure system over the Atlantic Ocean.  The high will steer Bertha toward the north on Thursday.  On its anticipated track Tropical Depression Bertha will move across western Virginia, West Virginia, eastern Ohio and western Pennsylvania.  Bertha will drop rain over those areas on Thursday.  Locally heavy rain could cause flooding in some locations.

Storm Storm Bertha Forms Near South Carolina

Tropical Storm Bertha formed quickly near the coast of South Carolina on Wednesday morning.  At 8:00 a.m. EDT on Wednesday the center of Tropical Storm Bertha was located at latitude 32.7°N and longitude 79.4°W which put it about 30 miles (50 km) east-southeast of Charleston, South Carolina.  Bertha was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1009 mb.

The National Hurricane Center issued a Tropical Storm Warning for the portion of the coast from Edisto Beach to South Santee River, South Carolina.

The circulation around a low pressure system off the southeast coast of the U.S. organized quickly on Wednesday morning.  A distinct center of circulation was evident on radar.  Radar and satellite images also showed bands of showers and thunderstorms revolving around the center of circulation.  NOAA buoy 41004 southeast of Charleston, South Carolina measured a sustained wind speed of 40 m.p.h. (65 km/h) and a gust to 58 m.p.h. (94 km/h).  Based on all of that information the National Hurricane Center designated the system as Tropical Storm Bertha.

Tropical Storm Bertha will move around the western end of a high pressure system over the Atlantic Ocean.  The high will steer Bertha toward the north during the next 24 hours.  On its anticipated track Tropical Storm Bertha will make landfall on the coast of South Carolina east of Charleston later on Wednesday.  Bertha will move over water where the Sea Surface Temperature is near 24°C.  It will move under the western side of an upper level ridge over the western Atlantic Ocean.  The ridge will produce southerly winds which will blow toward the top of the circulation.  Those winds will cause moderate vertical wind shear.  Based on recent trends Tropical Storm Bertha could strengthen before it makes landfall.  Bertha will drop heavy rain over eastern South Carolina and eastern North Carolina.  The heavy rain could cause floods in some locations.  Waves will cause erosion along the coast of South Carolina and North Carolina.

Major Hurricane Dorian Moves Toward the Carolinas

Major Hurricane Dorian moved toward the Carolinas on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Dorian was located at latitude 31.3°N and longitude 79.6°W which put it about 105 miles (170 km) south of Charleston, South Carolina.  Dorian was moving toward the north at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 115 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (220 km/h).  The minimum surface pressure was 955 mb.

A Hurricane Warning was in effect for the portion of the coast from Savannah River, Georgia to the North Carolina/Virginia border including Albemarle and Pamlico Sounds.  A Hurricane Watch was in effect for the portion of the coast from the mouth of the St. Mary’s River, Florida to Savannah River, Georgia.  Tropical Storm Warnings were in effect for the portions of the coast from the mouth of the St. Mary’s River to Savannah River, Georgia and from the North Carolina/Virginia border to Chincoteague, Virginia.  A Tropical Storm Warning was also in effect for Chesapeak Bay south of Smith Point.  Tropical Storm Watches were in effect for the portion of the coast from Chincoteague, Virginia to Fenwick Island, Delaware, for Chesapeake Bay from Smith Point to Drum Point and for the Tidal Potomac south of Cobb Island.

Hurricane Dorian strengthened back into a major hurricane on Wednesday night as it moved over the warm water in the Gulf Stream.  A large eye with a diameter of 45 miles (75 km) became more circular and symmetrical.  The ring of thunderstorms surrounding the eye became continuous and a little thicker.  The strongest winds were occurring in that ring of storms.  Other bands of showers and thunderstorms revolving around the core of Hurricane Dorian also got stronger.  Storms around the core of Dorian generated upper level divergence which pumped mass away from the hurricane and the surface pressure decreased.

The circulation around Hurricane Dorian increased in size on Wednesday.  Winds to hurricane force extended out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Dorian was 20.6.  The Hurricane Size Index (HSI) was 22.6 and the Hurricane Wind Intensity Size Index (HWISI) was 43.2.  Hurricane Dorian was capable of causing widespread major damage.

Hurricane Dorian will move through an environment favorable for intensification during the next 12 hours.  Dorian will move over water where the Sea Surface Temperature is near 28°C.  It will move through a region where the upper level winds are weak and there is little vertical wind shear.  Hurricane Dorian could get a little stronger during the night.  An upper level trough over the central U.S. will move toward Hurricane Dorian on Thursday.  The upper level trough will produce southwesterly winds which will blow toward the top of the hurricane.  Those winds will cause the vertical wind shear to increase, which will cause Dorian to start to weaken.

Hurricane Dorian will move around the western end of a subtropical ridge over the western Atlantic Ocean.  The ridge will steer Dorian toward the north on Wednesday night.  The upper level trough will turn Hurricane Dorian toward the northeast on Thursday.  On its anticipated track Hurricane Dorian could approach the coast of South Carolina on Thursday morning.  Dorian will move along the coast of North Carolina on Thursday afternoon and Thursday night.

Even if the center of Hurricane Dorian stays just south of the coast of South Carolina and North Carolina, the large circulation means that locations near the coast are likely to get hurricane force winds.  Winds blowing water toward the coast could cause storm surges of 5 to 8 feet (1.5 to 2.5 meters) in some locations.  Dorian could also drop locally heavy rain and cause flash flooding  near the coast.

Elsewhere, Tropical Storm Fernand made landfall north of La Pesca, Mexico on Wednesday and Tropical Storm Gabrielle developed south of the Azores.  Ar 11:00 p.m. EDT on Wednesday the center of Tropical Depression Fernand was located at latitude 25.0°N and longitude 99.0°W which put it about 100 miles (160 km) west-northwest of La Pesca, Mexico.  Dorian was moving toward the west-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1007 mb.

At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Gabrielle was located at latitude 21.5°N and longitude 34.4°W which put it about 1220 miles (1965 km) south-southwest of the Azores.  Gabrielle was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 m/h).  The minimum surface pressure was 1002 mb.

Powerful Hurricane Michael Nearing North Florida

Powerful hurricane Michael was nearing north Florida on Wednesday morning.  Michael intensified rapidly to Category 4 on the Saffir-Simpson Scale during the overnight hours.  At 8:00 a.m. EDT on Wednesday the center of Hurricane Michael was located at latitude 29.0°N and longitude 86.3°W which put it about 90 miles south-southwest of Panama City, Florida.  Michael was moving toward the north at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 933 mb.

A Hurricane Warning was in effect for the portion of the coast from the Alabama-Florida border to Suwanee River, Florida.  Tropical Storm Warnings were in effect for the portions of the coast from the Alabama-Florida border to the Alabama-Mississippi border and from Suwanee River to Chassahowitzka, Florida.  A Tropical Storm Warning was in effect for the Atlantic Coast from Fernandina Beach, Florida to Surf City, North Carolina.  Tropical Storm Watches were in effect for the portions of the coast from the Alabama-Mississippi border to the Mouth of the Pearl River and from Chassahowitzka to Anna Maria Island, Florida.  A Tropical Storm Watch was also in effect from Surf City to Duck, North Carolina including Albemarle and Pamlico Sounds.

Hurricane Michael intensified rapidly during the past 12 hours.  An eye with a diameter of 20 miles (32 km) is surrounded by a ring of strong thunderstorms.  The strongest winds are occurring in that ring of storms.  Storms near the core of Hurricane Michael are generating strong upper level divergence which is pumping large quantities of mass away from the hurricane.  The removal of mass allowed the surface pressure to decrease rapidly to 933 mb.

Winds to hurricane force extend out about 45 m.p.h. (75 km/h) from the center of Hurricane Michael.  Winds to tropical storm force extend out about 185 miles (290 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Michael is 29.9.  The Hurricane Size Index (HSI) is 16.1 and the Hurricane Wind Intensity Size Index (HWISI) is 46.0.  Hurricane Michael is capable of causing regional significant damage.

Hurricane Michael is stronger than any other hurricane to hit north Florida in the historical record.  Michael is similar in intensity to what Hurricane Charley was when Charley hit southwest Florida in 2004.  Hurricane Michael is bigger than Charley was in 2004.

An upper level trough over the Central U.S. and a subtropical high pressure system over the western Atlantic Ocean are combining to steer Hurricane Michael toward the north.  The trough will turn Michael toward the northeast when it reaches the coast.  On its anticipated track Hurricane Michael will make landfall near Panama City and Port St. Joe, Florida in about six hours.

Hurricane Michael will bring destructive winds to the coast of north Florida.  The strongest winds will be near the center and east of the center.  Those winds will push water toward the coast and a storm surge of 10 to 15 feet (3 to 5 meters) will occur east of where the center of Michael makes landfall.  The coast of the northeast Gulf of Mexico is very vulnerable to storm surges and significant damage will occur.

The center of Hurricane Michael will move between Dothan, Alabama and Tallahassee, Florida.  It will pass near Albany, Georgia and then move south of Macon, Georgia.  The center of Michael could move near Columbia, South Carolina and then it could exit the East Coast of the U.S. near Norfolk, Virginia.

Michael will bring hurricane force winds to northeast Florida, extreme southeast Alabama and southern Georgia.  There will be widespread power outages.  Winds to tropical storm force will occur in South Carolina and North Carolina.  Hurricane Michael will drop locally heavy rain when it moves inland.  The wind and rain will disrupt efforts to recover from the effects of Hurricane Florence in South Carolina and North Carolina.

Hurricane Florence Moves Closer to the Carolinas

Hurricane Florence moved closer to the Carolinas on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Florence was located at latitude 32.0°N and longitude 73.7°W which put it about 280 miles (455 km) east-southeast of Wilmington, North Carolina.  Florence was moving toward the northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 957 mb.

A Hurricane Warning was in effect for the portion of the coast from South Santee River, South Carolina to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Hurricane Watch was in effect for the portion of the coast from Edisto Beach, South Carolina to South Santee River, South Carolina.  A Tropical Storm Warning is in effect for the portion of coast from Duck, North Carolina to the North Carolina-Virginia border.  A Tropical Storm Watch was in effect for the portion of the coast from the North Carolina-Virginia border to Cape Charles Light, Virginia and for Chesapeake Bay south of New Point Comfort.

The wind speed in Hurricane Florence decreased on Wednesday but the circulation increased in size.  It appeared that another eyewall replacement cycle could have started.  Satellite microwave images suggested that there could be two eyewalls and a reconnaissance plane reported a double wind maxima.  Both of those things could be evidence of concentric eyewalls.  In addition, counterclockwise flow around a small upper level low near Florida may have produced southerly winds that blew toward the south side of Hurricane Frances.  Those winds may have inhibited the upper level divergence to the south of Florence.  Since the hurricane was unable to pump out as much mass, the surface pressure increased and the wind speed decreased.

The circulation of Hurricane Florence increased in size on Wednesday.  Winds to hurricane force extended out about 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Florence was 19.2.  The Hurricane Size Index (HSI) was 25.5 and the Hurricane Wind Intensity Size Index (HWISI) was 44.7.  Those indices are very similar to the numbers for Hurricane Jeanne just before Jeanne made landfall in southeast Florida in 2004.

Hurricane Florence will move through an environment favorable for intensification on Thursday.  Florence will move over water where the Sea Surface Temperature is near 29°C.  Florence will move farther away from the upper low near Florida and the low should not inhibit divergence to the south of the hurricane as much.  In addition, Hurricane Florence will move over the warm water in the Gulf Stream about 6 to 12 hours before it reaches the coast.  It will be able to extract extra energy at that time.  If the inner core becomes more organized, then Hurricane Florence could intensify on Thursday.  If the inner core does not get better organized, then Florence will likely maintain its current intensity or weaken slowly.

Hurricane Florence will move near the western end of the subtropical high pressure system over the western Atlantic Ocean.  The high will steer Florence toward the northwest on Thursday.  On its anticipated track the center of Hurricane Florence will be near the coast of North Carolina on Thursday night.  A ridge over the eastern U.S. is likely to block the northward motion of Hurricane Florence when it reaches the coast.  The ridge will steer Florence slowly toward the west-southwest on Friday and Saturday.

Hurricane Florence will have the impact of a major hurricane regardless of the actual sustained wind speed.  The large circulation and slow rate of movement when Florence reaches the coast means that locations could experience strong winds for extended periods of time.  Wind damage and power outages could be extensive.  Some places in North Carolina had a rainy summer and strong winds could uproot trees.  Hurricane Florence will produce a dangerous storm surge along the coast.  The surge could exceed 10 feet (3 meters) in some locations east of where the center makes landfall.  The slow forward speed also means that Hurricane Florence could drop locally heavy rain and severe flooding could occur.

Elsewhere the rest of the Atlantic Ocean was also very active.  Tropical Storm Isaac was nearing the Lesser Antilles, Hurricane Helene was weakening south of the Azores and Subtropical Storm Joyce formed northwest of Helene.

At 11:00 p.m. EDT on Thursday the center of Tropical Storm Isaac was located at latitude 15.3°N and longitude 58.0°W which put it about 220 miles (355 km) east of Dominica.  Isaac was moving toward the west at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1006 mb.  Tropical Storm Warnings were in effect for Guadeloupe, Martinique and Dominica.  Tropical Storm Watches were in effect for Antigua, Montserrat, St, Kitts and Nevis, Saba and St. Eustatius, St. Martin and St. Maarten.

At 11:00 p.m. EDT on Thursday the center of Hurricane Helene was located at latitude 22.4°N and 36.9°W which put it about 1270 mile (2045 km) south-southwest of the Azores.  Helene was moving toward the north at 13 m.p.h. (20 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 983 mb.

At 11:00 p.m. EDT on Thursday the center of Subtropical Storm Joyce was located at latitude 15.3°N and longitude 46.6°W which put it about 910 miles (1465 km) west-southwest of the Azores.  Joyce was moving toward the southwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1006 mb.

Hurricane Warnings Issued for Carolinas for Hurricane Florence

Hurricane Warnings were issued for the Carolinas on Tuesday for the potential impacts of Hurricane Florence.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Florence was located at latitude 28.4°N and longitude 68.7°W which put it about 670 miles (1075 km) east-southeast of Cape Fear, North Carolina.  Florence was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (270 km/h).  The minimum surface pressure was 946 mb.

A Hurricane Warning was in effect for the portion of the coast from South Santee River, South Carolina to Duck, North Carolina.  Hurricane Watches were in effect for the portions of the coast from Edisto Beach to South Santee River, South Carolina and from Duck, North Carolina to the North Carolina-Virginia border.  Tropical Storm Watches were in effect for the portions of the coast from Duck, North Carolina to Cape Charles Light, Virginia and for Chesapeake Bay south of New Point Comfort.

Hurricane Florence completed an eyewall replacement cycle and it continues to be a powerful hurricane.  There was a circular eye with a diameter of 30 miles (48 km) at the center of Florence.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  The eyewall replacement cycle resulted in a larger circulation.

Winds to hurricane force extended out about 60 miles (95 km) from the center of circulation of Hurricane Florence.  Winds to tropical storm force extended out about 175 miles (280 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Florence was 28.2.  The Hurricane Size Index (HSI) was 18.9 and the Hurricane Wind Intensity Size Index (HWISI) was 47.1.  Hurricane Florence is capable of causing extensive significant damage.

Hurricane Florence will move through an environment favorable for strong hurricanes during the next 24 to 36 hours.  Florence will move over water where the Sea Surface Temperature is near 29°C.  it will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Florence is likely to maintain its intensity and it could strengthen.  If another eyewall replacement cycle occurs, then there could be fluctuations in intensity.

Hurricane Florence will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Florence toward the west-northwest during the next 24 to 36 hours.  On its anticipated track Hurricane Florence could approach the coast of the Carolinas later on Thursday.  The steering winds are forecast to weaken when Florence nears the coast and there is great uncertainty about the track when that occurs.  Hurricane Florence will bring strong winds to coastal North Carolina and eastern South Carolina.  Wind pushing water toward the shore will cause a significant storm surge.  A slow forward speed will mean that Hurricane Florence will drop a lot of rain and there is a risk of significant flooding of rivers and streams.

Elsewhere over the Atlantic Ocean, Tropical Storm Isaac was speeding toward the Lesser Antilles and Hurricane Helene was weakening far south of the Azores.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Isaac was located at latitude 14.5°N and longitude 52.3°W which put it about 580 miles (935 km) east of Martinique.  Isaac was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 999 mb.  Tropical Storm Warnings were in effect for Dominica, Martinique and Guadeloupe.  Tropical Storm Watches were in effect for Antigua, Montserrat, St. Kitts and Nevis, and Saba and St. Eustatius.

At 11:00 p.m. EDT on Tuesday the center of Hurricane Helene was located at latitude 18.0°N and longitude 35.4°W which put it about 1479 miles (2370 km) south-southwest of the Azores.  Helene was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 973 mb.