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Isaias Strengthens Back into a Hurricane

Isaias strengthened back into a hurricane on Monday evening.  At 9:00 p.m. EDT on Monday the center of Hurricane Isaias was located at latitude 33.1°N and longitude 78.8°W which put it about 55 miles (90 km) south-southeast of Myrtle Beach, South Carolina.  Isaias was moving toward the north-northeast at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 988 mb.

A Hurricane Warning was in effect for the portion of the coast from South Santee River, South Carolina to Surf City, North Carolina.  Tropical Storm Warnings were in effect for the portion of the coast from Edisto Beach to South Santee River, South Carolina and from Surf City, North Carolina to Stonington, Maine including Albemarle Sound, Pamlico Sound, Long Island, Long Island Sound, Block Island, Martha’s Vineyard, and Nantucket.  A Tropical Storm Watch was in effect for the portion of the coast from Stonington, to Eastport, Maine.

The circulation around Hurricane Isaias became much better organized on Monday afternoon.  A reconnaissance aircraft investigating Isaias found winds to hurricane force.  An elliptical eye developed at the center of Hurricane Isaias.  A broken ring of thunderstorms surrounded the elliptical eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Isaias.  The strongest rainbands were in the northern half of the circulation.  Bands in the southern half of Hurricane Isaias consisted primarily of showers and lower clouds.  Winds to hurricane force extended out 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out 125 miles (200 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Isaias was 12.7.  The Hurricane Size Index (HSI) was 15.3 and the Hurricane Wind Intensity Size Index (HWISI) was 28.0.  Hurricane Isaias was capable of causing regional minor damage.

The center of Hurricane Isaias will make landfall between Myrtle Beach, South Carolina and Southport, North Carolina during the next few hours.  Isaias will bring hurricane force winds to the portion of the coast from Myrtle Beach, South Carolina to Surf City, North Carolina.  It will generate a storm surge of 3 to 6 feet (1 to 2 meters) along the coast.  Hurricane Isaias will drop heavy rain over extreme eastern South Carolina, eastern North Carolina and eastern Virginia.  Heavy rain could cause flooding in some locations.

The center of Hurricane Isaias will pass just west of Norfolk, Virginia on Tuesday morning.  isaias will weaken when it passes over land, but it will still bring gusty winds over eastern Virginia.  Isaias will pass near New York City on Tuesday evening and it will bring gusty winds to New England on Tuesday night.  Isaias could cause widespread power outages along the East Coast of the U.S.  It will also drop heavy rain east of the Appalachians and flash floods could occur in that region.

Tropical Storm Isaias Turns Toward the Carolinas

Tropical Storm Isaias turned toward the Carolinas on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Isaias was located at latitude 30.7°N and longitude 80.1°W which put it about 220 miles (350 km) south-southwest of Myrtle Beach, South Carolina.  Isaias was moving toward the north at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 998 mb.

A Hurricane Warning was in effect for the portion of the coast from South Santee River, South Carolina to Surt City, North Carolina.  Tropical Storm Warnings were in effect for the portions of the coast from Altamaha Sound, Georgia to South Santee River, South Carolina and from Surf City North Carolina to Watch Hill, Rhode Island including Albemarle Sound, Pamlico Sound, Long Island and Long Island Sound.  A Tropical Storm Watch was in effect for the portion of the coast from Watch Hill, Rhode Island to Stonington, Maine including Block Island, Martha’s Vineyard and Nantucket.

Tropical Storm Isaias seemed to begin another cycle where the thunderstorm activity pulsed down during the overnight hours.  However, visible satellite and radar images seemed to indicate that thunderstorms were starting redevelop on Monday morning.  A band of thunderstorms appeared to be wrapping around the northern side of the circulation.  Thunderstorms were also increasing in bands in the northern and eastern parts of Isaias.  Bands in the southern and western sides of Isaias consisted primarily of showers and lower clouds.  The circulation of Tropical Storm Isaias could be pulling in some drier air around the southern and western parts of the storm.  That is a fairly typical occurrence with tropical systems moving up the East Coast of the U.S.  Winds to tropical storm force extended out 125 miles (200 km) in the northern and eastern quadrants of Isaias.  The winds in the southern and western parts of the circulation were mostly at less than tropical storm force.

Tropical Storm Isaias will move through an environment somewhat favorable for intensification during the next 12 hours.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the Central U.S. will produce southwesterly winds which will blow toward the top of Isaias.  Those winds will cause moderate vertical wind shear which will inhibit intensification.  The wind shear is expected to decrease slightly later on Monday, which could allow Isaias to strengthen into a hurricane.

The upper level trough will steer Tropical Storm Isaias toward the north-northeast during the next several days.  On its anticipated track Tropical Storm Isaias will make landfall near Myrtle Beach, South Carolina on Monday night.  Isaias could be a hurricane when it makes landfall.  Isaias will bring gusty winds and a storm surge of 3 to 6 feet (1 to 2 meters) to the coast near and to the east of where the center makes landfall.  The center of Isaias will move across eastern North Carolina and it could be near Norfolk, Virginia on Tuesday morning.  Tropical Storm Isaias could pass near New York City later on Tuesday.

Tropical Storm Isaias will bring gusty winds to the East Coast of the U.S. from South Carolina to Maine.  Isaias will also drop locally heavy rain from eastern South Carolina to New England.  The National Weather Service has indicated that a Moderate Risk of flash floods exists for the region from eastern South Carolina to eastern Pennsylvania.

Tropical Storm Isaias Slightly Stronger, Hurricane Watch Issued for Carolinas

Tropical Storm Isaias strengthened slightly on Sunday afternoon and a hurricane Watch was issued for a portion of the Carolinas’ coast.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Isaias was located at latitude 27.8°N and longitude 79.8°W which put it about 65 miles (105 km) southeast of Cape Canaveral, Florida.  Isaias was moving toward the north-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 994 mb.

A Hurricane Watch was issued for the portion of the coast from South Santee River, South Carolina to Surf City, North Carolina.  A Tropical Storm Warning was in effect for the portion of the coast from Sebastian Inlet, Florida to Ocracoke Inlet, North Carolina.  A Tropical Storm Watch was issued for the portion of the coast from Ocracoke Inlet, North Carolina to Watch Hill, Rhode Island including Albemarle Sound, Pamlico Sound, Long Island and Long Island Sound.

Tropical Storm Isaias strengthened a little on Sunday afternoon, but the middle level center of circulation was displaced to the northeast of the surface center.  An upper level trough over the central U.S. extended to the Gulf of Mexico and it was producing westerly winds which were blowing toward the top of Isaias.  Those winds were causing moderate vertical wind shear and they were also causing the displacement of the middle level center of Tropical Storm Isaias.  Thunderstorms continued to develop around the middle level center of circulation.  Those storms generated upper level divergence which pumped mass away to the east of the tropical storm.  Winds to tropical storm force extended out 115 miles (185 km) on the eastern side of Isaias.  Tropical Storm force winds only extended out 65 miles (105 km) on the western side of the circulation.

Tropical Storm Isaias will move through an environment somewhat favorable for intensification during the next 24 hours.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  The direction of the upper level winds will shift to the southwest as the upper level trough approaches Tropical Storm Isaias.  That will cause the vertical wind shear to decrease.  Tropical Storm Isaias could strengthen into a hurricane, if the shear decreases.

Tropical Storm Isaias will move around the western end of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer Isaias toward the north during the next 12 hours.  The upper level trough will steer Tropical Storm Isaias toward the northeast on Monday.  On its anticipated track Isaias will approach the coast of the Carolinas near Myrtle Beach, South Carolina on Monday night.  Isaias could be a hurricane when it makes landfall.  It will bring gusty winds and locally heavy rain to extreme eastern South Carolina, eastern North Carolina and coastal Virginia.  Isaias will cause a storm surge of 3  to 6 feet (1 to 2 meters) near and to the east of where the center makes landfall.  Tropical Storm Isaias will continue to move up the East Coast toward New England.

Tropical Storm Fay Forms East of Cape Hatteras

Tropical Storm Fay formed east of Cape Hatteras on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Fay was located at latitude 35.5°N and longitude 74.9°W which put it about 40 miles (65 km) east-northeast of Cape Hatteras, North Carolina.  Fay was moving toward the north at 7 m.p.h. (11 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 1005 mb.

A Tropical Storm Warning was issued for the portion of the coast from Cape May, New Jersey to Watch Hill, Rhode Island including Long Island and Long Island Sound.

A new center of circulation formed near the northern end of a band of showers and thunderstorms which was on the eastern side of a larger low pressure system that was previously designated as Invest 98L.  A reconnaissance aircraft detected winds to tropical storm force and the National Hurricane Center designated the system as Tropical Storm Fay.  Fay is the sixth named Atlantic tropical storm of 2020 and it formed earlier than any other sixth Atlantic tropical storm in the satellite era.

The circulation around Tropical Storm Fay was asymmetrical.  The strongest winds were occurring a band of showers and thunderstorms on the eastern side of Fay.  The inner end of the band was wrapping around the northern side of the center of circulation.  Bands on the western side of the tropical storm consisted primarily of showers and lower clouds.  Storms near the center began to generate upper level divergence which was pumping mass away to the north and east of the tropical storm.  Winds to tropical storm force extended out about 140 miles (225 km) in the eastern half of Tropical Storm Fay.  The winds in the western half of Fay were blowing at less than tropical storm force.

Tropical Storm Fay will move through an environment somewhat favorable for intensification during the next 18 to 24 hours.  Fay will move over water where the Sea Surface Temperature is near 26°C.  An upper level trough over the eastern U.S. will produce southwesterly winds which will blow toward the top of the tropical storm.  Those winds will impede upper level divergence to the west of Tropical Storm Fay and they will cause moderate vertical wind shear.  The wind shear will inhibit intensification, but it will not likely to be strong enough to prevent Fay from strengthening.  Tropical Storm Fay could intensify during the next 12 to 18 hours.

The upper level trough and a high pressure system over the Atlantic Ocean will interact to steer Tropical Storm Fay toward the north during the next day or two.  On its anticipated track the center of Tropical Storm Fay could approach southern New Jersey on Friday afternoon.  Fay could move across Long Island on Friday night.

Since the strongest rainband and winds are on the eastern side of Tropical Storm Fay, the portion of the coast south of New Jersey may not experience tropical storm force winds.  Gusty winds are likely along the coast of New Jersey, Long Island, southeastern New York, Connecticut and Rhode Island.  Heavy rain could also fall in those locations.  Easterly winds blowing around the northern side of Tropical Storm Fay will push water toward the coast.  The water level could rise several feet (one meter) at some locations.  Waves could also cause some beach erosion.

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.

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.

Hurricane Florence Causes Watches for Carolinas, Isaac for the Lesser Antilles

The potential impacts of Hurricane Florence caused Hurricane Watches to be issued for the Carolinas on Tuesday morning while the approach of Tropical Storm Isaac also caused Watches to be issued for some of the Lesser Antilles.  At 11:00 a.m. EDT on Tuesday the center of Hurricane Florence was located at latitude 26.7°N and longitude 65.3°W which put it about 905 miles (1455 km) east-southeast of Cape Fear, North Carolina.  Florence was moving toward the west-northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 950 mb.  A Hurricane Watch was in effect for the portion of the coast from Edisto Beach, South Carolina to the North Carolina-Virginia border including Pamlico and Albemarle Sounds.

Hurricane Florence was nearing the end of an eyewall replacement cycle on Tuesday morning.  A thin ring of showers and thunderstorms around the center of circulation was all that was left of the original eyewall.  A larger ring of thunderstorms surrounded an eye with a diameter of 36 miles (58 km).  Several other bands of showers and thunderstorms surround the new, larger eyewall.  Storms near the core of Hurricane Florence generated strong upper level divergence which pumped mass away from the hurricane.

The eyewall replacement cycle temporarily weakened Hurricane Florence, but it also made the circulation larger.  Winds to hurricane force extended out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extended out about 150 miles (240 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Florence was 25.1.  The Hurricane Size Index (HSI) was 15.3 and the Hurricane Wind Intensity Size Index (HWISI) was 40.4.

Hurricane Florence will be moving through an environment favorable for strong hurricanes.  Florence will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Florence is likely to strengthen during the next 24 hours, but additional eyewall replacement cycles could cause the intensity to fluctuate.

Hurricane Florence will move around the western end of the subtropical high pressure system over the western Atlantic Ocean.  The high will steer Florence in a general west-northwesterly direction.  On its anticipated track the center of Hurricane Florence could approach the coast of North Carolina and South Carolina on Thursday.  It will very likely be a major hurricane at that time.

Tropical Storm Isaac moved steadily toward the Lesser Antilles and Watches were issued for some of those islands.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Isaac was located at latitude 14.6°N and longitude 49.7°W which put it about 775 miles (1250 km) east of the Lesser Antilles.  Isaac was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 996 mb.  Hurricane Watches were in effect for Guadeloupe, Martinique and Dominica.  Tropical Storm Watches were in effect for Antigua and Montserrat.

Elsewhere over the tropical Atlantic Ocean, Hurricane Helene moved far south of the Azores.  At 11:00 a.m. EDT on Tuesday the center of Hurricane Helene was located at latitude 16.5°N and longitude 34.3°W which put it about 1550 miles (2495 km) south-southwest of the Azores.  Helene was moving toward the northwest at 12 m.p.h. (19 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 966 mb.

Florence Strengthens Into a Major Hurricane

Hurricane Florence strengthened into a Major Hurricane on Monday.  At 11:00 p.m. EDT on Monday the center of Hurricane Florence was located at latitude 25.9°N and longitude 62.4°W which put it about 1085 miles (1745 km) east-southeast of Cape Fear, North Carolina.  Florence was moving toward the west-northwest at 13 m.p.h. (20 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 944 mb.

Hurricane Florence intensified rapidly on Monday morning and early afternoon.  An eye with a diameter of 18 miles (29 km) formed at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Hurricane Florence.  Storms near the core were generating strong upper level divergence which pumped mass away from the hurricane.

Hurricane Florence increased in size on Monday.  Winds to hurricane force extended out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extended out about 150 miles (240 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Florence was 28.2.  The Hurricane Size Index (HSI) was 14.0 and the Hurricane Wind Intensity Size Index (HWISI) was 42.2.  Hurricane Florence was capable of causing extensive significant damage.

Microwave satellite imagery indicated that an inner rainband may have wrapped around the original eye and eyewall.  An eyewall replacement cycle may have begun and that may have halted the rapid intensification of Hurricane Florence.  Florence could weaken during the next few hours while the inner eyewall weakens.  Hurricane Florence will move through an area capable of supporting strong hurricanes on Tuesday and Wednesday.  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.  If the inner eyewall dissipates during the next day or so, then Hurricane Florence could strengthen again.

Hurricane Florence will move around the western end of the subtropical high pressure system during the next several days.  The high will steer Florence toward the west-northwest.  On its anticipated track Hurricane Florence will approach the coast of North Carolina on Thursday afternoon.  The winds steering Florence could weaken as it approaches the coast and the track forecast becomes much more uncertain at that time.

Elsewhere, Hurricane Helene and Tropical Storm Isaac were spinning over the tropical Atlantic Ocean.  At 11:00 p.m. EDT on Monday the center of Hurricane Helene was located at latitude 15.5°N and longitude 32.4°W which put it about 1590 miles (2555 km) south of the Azores.  Helen was moving toward the west-northwest at 12 m.p.h. (19 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 968 mb.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Isaac was located at latitude 14.5°N and longitude 46.9°W which put it about 960 miles (1550 km) east of the Lesser Antilles.  Isaac was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 997 mb.

Florence Strengthens Back Into a Hurricane

Florence strengthened back into a hurricane on Sunday morning.  At 11:00 a.m. EDT on Sunday the center of Hurricane Florence was located at latitude 24.4°N and longitude 56.3°W which put it about 750 miles (1210 km) southeast of Bermuda.  Florence was moving toward the west at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 984 mb.

Hurricane Florence was better organized on Sunday morning.  A NOAA research aircraft reported a circular eye with a diameter of 24 miles (39 km).  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Hurricane Florence.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.  Winds to hurricane force extended out about 20 miles (35 km) to the east of the center of circulation.  Winds to tropical storm force extended out about 115 miles (185 km) to the north of the center and about 50 miles (80 km) to the south of the center.

Hurricane Florence will be moving through an environment favorable for intensification.  Florence will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Florence will strengthen and it could intensify rapidly at times.  Florence is likely to be a major hurricane on Monday.

Hurricane Florence will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Florence in a general west-northwesterly direction.  On its anticipated track the center of Hurricane Florence will approach the southeast coast of the U.S. on Thursday.  It is likely to be a major hurricane at that time.

Elsewhere, Tropical Storm Helene and Tropical Storm Isaac moved westward over the tropical Atlantic Ocean.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Helene was located at latitude 13.2°N and longitude 25.0°W which put it about 120 miles (195 km) south-southwest of the Cabo Verde Islands.  Helene was moving toward the west at 13 m.p.h. (20 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 997 mb.  Tropical Storm Warnings were in effect for Santiago, Fogo and Brava.

At 11:00 a.m. EDT on Sunday the center of Tropical Storm Isaac was located at latitude 14.3°N and longitude 39.1°W which put it about 1470 miles (2370 km) east of the Windward Islands.  Isaac was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 65 m.p.h. (105km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 999 mb.

Tropical Storm Florence Reorganizes Southeast of Bermuda

Tropical Storm Florence reorganized southeast of Bermuda on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Florence was located at latitude 24.6°N and longitude 55.2°W which put it about 790 miles (1270 km) southeast of Bermuda.  Florence was moving toward the west at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 989 mb.

Vertical wind shear decreased around Tropical Storm Florence and the circulation showed evidence of better organization.  Stronger thunderstorms developed near the center of circulation and a primary rainband wrapped about three quarters of the way around the center.  An eye appeared to be forming.  Thunderstorms near the center generated more upper level divergence which pumped away mass and the surface pressure decreased on Saturday.  More thunderstorms also developed in other rainbands that were revolving around the core of the circulation.  Tropical Storm Florence appeared to be on the threshold of regaining hurricane intensity.

Tropical Storm Florence will be moving through an environment favorable for intensification during the next two or three days.  Florence will move over water where the Sea Surface Temperature is near 29°C.  It will move into a region where the upper level winds are weaker and there will be less vertical wind shear.  Tropical Storm Florence will intensify back into a hurricane on Sunday.  It could intensify rapidly once a eye and complete eyewall form.  Florence is likely to become a major hurricane by early next week.

Tropical Storm Florence will move near the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Florence in a general west-northwesterly direction during the next few days.  On its anticipated track Florence could approach the southeast coast of the U.S. by Thursday.  It is likely to be a major hurricane at that time.  The steering currents could weaken when Florence approaches the U.S. and it is too early to make a precise forecast of landfall.

Elsewhere, Tropical Storms Helene and Isaac strengthened over the eastern tropical Atlantic Ocean.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Helene was located at latitude 13.2°N and longitude 22.8°W which put it about 155 miles (250 km) southeast of the Cabo Verde Islands.  Helene was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120km/h).  The minimum surface pressure was 999 mb.  Tropical Storm Warnings were in effect for Santiago, Fogo and Brava.

At 11:00 p.m. EDT the center of Tropical Storm Isaac was located at latitude 14.4°N and longitude 37.5°W which put it about 1580 miles (2540 km) east of the Windward Islands.  Isaac was moving toward the west at 8 m.p.h. (13 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 1002 mb.