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Tropical Storm Isaias Speeds Past New York City

Tropical Storm Isaias sped past New York City on Tuesday afternoon.  At 2:00 p.m. EDT on Tuesday the center of Tropical Storm Isaias was located at latitude 40.9°N and longitude 75.1°W which put it about 65 miles (105 km) west of New York, New York.  Isaias was moving toward the north-northeast at 40 m.p.h. (65 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 994 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Chincoteague, Virginia to Eastport, Maine including Long Island, Long Island Sound, Block Island, Martha’s Vineyard and Nantucket.

Tropical Storm Isaias sped up the East Coast of the U.S. on Tuesday and the center of circulation was west of New York City by Tuesday afternoon.  Isaias was still generating an area of winds to tropical storm force over the Atlantic Ocean.  A NOAA buoy at the entrance to New York Harbor measured a sustained wind speed of 57 m.p.h. (83 km/h) and a wind gust of 71 m.p.h. (115 km/h).  JFK airport recently reported a wind gust to 70 m.p.h. (113 km/h).

The eastern side of former Hurricane Isaias produced strong wind gusts along the East Coast of the U.S. from North Carolina to Long Island.  A station at Federal Point, North Carolina reported a gust of 99 m.p.h.  (160 km/h).  Wrightsville Beach, North Carolina had a wind gust to 86 m.p.h. (139 km/h).  Stevensville, Maryland measured a gust of 79 m.p.h. (127 km/h).  South Norfolk, Virginia reported a wind gust to 76 m.p.h. (122 km/h) and Nags Head, North Carolina had a gust of 75 m.p.h. (120 km/h).  Ocean City, Maryland measured a gust of 69 m.p.h. (111 km/h).

The strong wind gusts caused widespread power outages.  Shear in the lower levels of the atmosphere also contributed to the spinup of a number of tornadoes.  Tropical Storm isaias dropped heavy rain over parts of the northeastern U.S.  Isaias will continue to speed north-northeastward into Canada during the next 12 hours.  Tropical Storm Isaias will gradually weaken and wind speeds should decrease.  Isaias will continue to drop locally heavy rain over eastern New York, western Massachusetts and Vermont for several more hours.  The potential for flash floods in those areas still exists.

Hurricane Isaias Brings Wind and Rain to MidAtlantic States

Hurricane Isaias brought wind and rain to the MidAtlantic states of the U.S. on Tuesday.  Isaias weakened to a tropical storm on Tuesday morning as it moved over eastern Virginia.  At 8:00 a.m. EDT on Tuesday the center of Tropical Storm Isaias was located at latitude 37.7°N and longitude 76.8°W which put it about 15 miles (25 km) south-southeast of Tappahannock, Virginia.  Isaias was moving toward the north-northeast at 33 m.p.h. (54 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 993 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Surf City, North Carolina to Eastport, Maine including Albemarle Sound, Pamlico, Sound, Long Island, Long Island Sound, Block Island, Martha’s Vineyard and Nantucket.

The center of Hurricane Isaias officially made landfall on the coast at Ocean Isle Beach, North Carolina.  The maximum sustained wind speed at the time of landfall was 85 m.p.h. (135 km/h).  A weather station at Oak Island, North Carolina measured a sustained wind speed of 76 m.p.h. and a wind gust to 87 m.p.h. (140 km/h).

The center of Isaias moved rapidly toward the north-northeast during the overnight hours and it passed between Richmond and Norfolk, Virginia.  The strongest winds were occurring along the coast and over the Atlantic Ocean on Tuesday morning.  A weather station at Duck, North Carolina measured a sustained wind speed of 48 m.p.h. (78 km/h) and a wind gust of 63 m.p.h. (102 km/h).  A weather station at Poquoson, Virginia measured a sustained wind speed of 39 m.p.h. (63 km/h) and a wind gust to 56 m.p.h. (91 km/h).  A weather station on Third Island which is near the Mouth of Chesapeake Bay recently measured a sustained wind speed of 63 m.p.h. (101 km/h) and a wind gust of 77 m.p.h. (124 km/h).

Tropical Storm Isaias will move rapidly toward the north-northeast during the next 24 hours.  The center of Isaias will pass west of New York City later today.  Tropical Storm Isaias will gradually weaken, but it could bring tropical storm force winds to the northeastern U.S.  Wind shear in the lower levels of Tropical Storm Isaias’ circulation is contributing to the spin up of tornadoes.  Isaias will drop locally heavy rain and flash floods could occur.

Tropical Storm Isaias will take a track similar to the tracks taken by Hurricane Irene in 2011 and Hurricane Isabel in 2003.  Hurricane Irene was similar in strength and a little bit larger than Isaias when it hit North Carolina in 2011.  Irene was already weakening when it hit the coast while Isaias was strengthening at landfall.  According to the Tropical Cyclone Report on the National Hurricane Center’s (NHC) website, Hurricane Irene caused 15.8 billions dollars of damage in the U.S.

Hurricane Isabel was larger and stronger than Isaias was when it made landfall in North Carolina.  Isabel was also weakening at the time of landfall.  According to the Tropical Cyclone Report on NHC’s website for Hurricane Isabel, it caused 5.4 billion dollars of damage in the U.S.

 

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 Weakens Over New York

Tropical Storm Fay weakened over New York on Friday night.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Fay was located at latitude 41.0°N and longitude 74.2°W which put it about 15 miles (30 km) northwest of New York, New York.  Fay was moving toward the north at 17 m.p.h. (28 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 1001 mb.

A Tropical Storm Warning was in effect for the portion of the coast from East Rockaway, New York to Watch Hill, Rhode Island including Long Island and Long Island Sound.

Tropical Storm Fay weakened on Friday night as the center moved across eastern New Jersey and into southeastern New York.  An upper level trough over the eastern U.S. was producing southwesterly winds which were blowing across the top of Fay.  Those winds were causing moderate vertical wind shear.  Drier air was wrapping around the southern side of the circulation and it was being pulled into the inner part of Tropical Storm Fay.  Bands near the center of Fay consisted of showers and lower clouds.  Heavier rain was falling in bands over northeastern Pennsylvania and central New York.  Winds to tropical storm force were occurring in the southeastern part of the circulation which is still over the Atlantic Ocean.  The wind speeds over land were much weaker.

The upper level trough will steer Tropical Storm Fay toward the north-northeast during the next several days.  Fay will continue to weaken as the tropical storm moves farther inland.  Tropical Storm Fay will also make a transition to an extratropical cyclone when it moves farther north.  Fay could still drop locally heavy rain over parts of the northeastern U.S. on Saturday.

Tropical Storm Fay Drops Heavy Rain on Delaware and New Jersey

Tropical Storm Fay dropped heavy rain on parts of Delaware and southern New Jersey on Friday morning.  At 8:00 a.m. EDT on Friday the center of Tropical Storm Fay was located at latitude 37.6°N and longitude 74.7°W which put it about 90 miles (145 km) south of Cape May, New Jersey.  Fay was moving toward the north at 10 m.p.h. (16 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 999 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Fenwick Island, Delaware to Watch Hill, Rhode Island including southern Delaware Bay, Long Island and Long Island Sound.

Tropical Storm Fay intensified slowly on Friday morning.  A reconnaissance aircraft reported that the minimum surface pressure decreased to 999 mb.  A ring of showers and lower clouds encircled the center of Tropical Storm Fay.  Bands of showers and thunderstorms wrapped around the northern and western sides of Fay.  Bands in the southern part of the circulation consisted primarily of showers and lower clouds.  Drier air was wrapping around the southern portion of the tropical storm.  Winds to tropical storm force extended out 140 miles (225 km) in the eastern side of Tropical Storm Fay.  Winds to tropical storm force extended out 80 miles (130 km) on the western side of the circulation.

Tropical Storm Fay will move through an environment that could allow for some additional intensification during the next few 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 circulation.  Those winds will cause moderate vertical wind shear.  The shear will inhibit intensification, but it may not be strong enough to prevent Tropical Storm Fay from strengthening a little more.

The upper level trough over the eastern U.S. and a high pressure system over the Atlantic Ocean will interact to steer Tropical Storm Fay toward the north-northeast during the next several days.  On its anticipated track Fay could approach the coast of New Jersey in a few hours.  Tropical Storm Fay will move across Long Island on Friday night.

Tropical Storm Fay will bring gusty winds to the coast of Delaware, New Jersey, New York, Connecticut and Rhode Island.  Locally heavy rain will fall over those areas as the center of Fay approaches.  Flood Watches have been issued for parts of Delaware, New Jersey, eastern Pennsylvania, southeastern New York, Connecticut and western Massachusetts.   Easterly winds blowing around the north side of Tropical Storm Fay could push water toward the coast.  Water Level rises of three feet (1 meter) could occur in some locations.

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 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.