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Hurricane Matthew Causing Serious Flooding in the Carolinas

Hurricane Matthew produced heavy rainfall which led to serious flooding in South Carolina and North Carolina on Saturday.  The total rainfall in some locations exceeded 10 inches (25 cm) in numerous locations in those two states.  Heavy prolonged rain caused creeks and rivers to rapidly rise and flood.

The National Hurricane Center (NHC) still classified Hurricane Matthew as a hurricane in its 11:00 p.m. EDT advisory.  At 11:00 p.m. EDT on the center of Hurricane Matthew was located at latitude 34.1°N and longitude 76.5°W which put it about 35 miles (55 km) south of Cape Lookout, North Carolina.  Matthew was moving toward the east-northeast at 14 m.p.h. (22 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 982 mb.

A Hurricane Warning is in effect for the portion of the coast from Little River Inlet to Surf City, North Carolina.  A Hurricane Watch has been issued for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Warning is in effect for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.

According to NHC the center of Hurricane Matthew made an official landfall near Cape Romain southeast of McClellanville, South Carolina at 11:00 a.m. EDT on Saturday.  Since that time the center of Hurricane Matthew has moved back out over the Atlantic Ocean.  New bands of showers are forming closer to the center south of the coast of North Carolina.  The winds to hurricane force are occurring over a small area on the southwestern side of Hurricane Matthew.

Easterly winds blowing around the north side of Hurricane Matthew converged with northerly winds blowing along a cold front to generate a broad area of rising motion.  The rising motion and the existing rainbands of the hurricane combined to produce very heavy rain over South Carolina and the southeastern half of North Carolina.  The area of heavy rain spread into southeastern Virginia around Norfolk on Saturday night.  The prolonged heavy rainfall caused the water in creeks and rivers to rise very quickly.  Serious flooding was occurring in parts of South Carolina and North Carolina.  Numerous roads were closed because of flooding in those two states.

Along the coast of North Carolina southeasterly winds were blowing water toward the coast and Hurricane Matthew was still generating storm surges.  When Matthew moves east of the Outer Banks of North Carolina, the wind will change direction and it will blow from the northwest.  Those northwesterly winds will push water in Pamlico and Albemarle Sounds onto the western sides of the Outer Banks.  Storms surges caused by Hurricane Matthew caused varying amounts of damage from Florida to North Carolina.  The most destructive storm surges appear to have been near Jacksonville Beach, Florida, around the barrier islands of Georgia and South Carolina.  However, a full damage assessment has not been made of those locations at this time.

Even though the center of Hurricane Matthew stayed over the Atlantic Ocean most of the time, gusty winds caused power outages from Florida to North Carolina.  As the heavy rain saturated the ground, gusts of winds toppled trees which fell onto power lines.  More power outages are likely in eastern North Carolina and southeastern Virginia as more trees are uprooted.

Hurricane Matthew will slowly move out to sea on Sunday.  Matthew appears to be making a transition to an extratropical cyclone.  During that transition the wind field is likely to expand.  So, conditions should improve slowly over North Carolina and Virginia on Sunday.

Hurricane Matthew Bringing Wind and Heavy Rain to the Carolinas

Hurricane Matthew was bringing wind and heavy rain to South Carolina and North Carolina on Saturday morning after causing damage along the coasts of Florida and Georgia on Friday.  At 9:00 a.m. EDT on Saturday the center of Hurricane Matthew was located at latitude 32.6°N and longitude 79.7°W which put it about 30 miles (50 km) southeast of Charleston, South Carolina.  Matthew was moving toward the northeast at 12 m.p.h. (19 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 963 mb.

A Hurricane Warning is in effect for the portion of the coast from Altamaha Sound, Georgia to Surf City, North Carolina.  A Hurricane Watch is in effect for the portion of the coast from Surf City to Cape Lookout, North Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Surf City to Duck, North Carolina.

The center of Hurricane Matthew is moving just south of the coast of South Carolina.  The winds to hurricane force are occurring in a small area over the Atlantic ocean near the center of Matthew.  Wind gusts to near hurricane force were occurring occasionally at the coast.  Beaufort, South Carolina reported a wind gust to 71 m.p.h. (114 km/h).  Earlier on Saturday a pier at Foley Beach, South Carolina reported a wind gust to 76 m.p.h. (122 km/h).  Inland stations in South Carolina and North Carolina were reporting winds in the range of 20 to 50 m.p.h. (30 to 80 km) with occasional higher gusts.

The wind damage caused by Hurricane Matthew is likely to be minor in many locations.  The winds are strong enough to bring down trees and cause widespread power outages.  There are also some stronger thunderstorms in some of the rainbands that are capable of causing more severe local wind damage and could spin up brief tornadoes.  Hurricane Matthew is also producing heavy rain over South Carolina and North Carolina.  The relatively slow movement of Hurricane Matthew could produce prolonged periods of heavy rain and cause fresh water flooding.  In addition, southeasterly winds on the east side of Hurricane Matthew are pushing water toward the shore and are causing storm surges at the coast.

An upper level trough over the eastern U.S. is steering Hurricane Matthew toward the northeast and that general motion will continue to today.  On its anticipated track the center of Hurricane Matthew will move very near the coast of South Carolina and North Carolina.  Since about half of the circulation of Hurricane Matthew is over land, friction will cause the hurricane to weaken slowly.

Hurricane Matthew Brings Wind, Rain and Surge to Northeast Florida

Hurricane Matthew brought gusty winds, heavy rain and storm surges to northeast Florida as the center of the hurricane moved northward just east of Florida on Friday.  A weather station on the tip of Cape Canaveral reported a wind gust to 107 m.p.h. (170 km/h) when the western side of the eyewall moved over that location.  Wind gusts to 71 m.p.h. (115 km/h) were reported at Daytona Beach.  A wind gust to 86 m.p.h. (139 km/h) was reported by a C-MAN station in St. Augustine, Florida.  Some wind damage and numerous power outages were reported in conjunction with the strong winds.  Easterly winds pushing water toward the coast were generating storms surges along the coast.

At 5:00 p.m. EDT on Friday the center of Hurricane Matthew was located at latitude 30.2°N and longitude 80.7°W which put it about 40 miles (65 km) east of Jacksonville Beach, Florida and about 135 miles (215 km) south of Savannah, Georgia.  Matthew was moving toward the north 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 948 mb.  Hurricane Matthew was a Category 2 hurricane on the Saffir-Simpson Scale.

A Hurricane Warning is in effect for the portion of the coast from the Flagler/Volusia County line in Florida to Surf City, North Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Warning is also in effect for the portion of the coast from the Brevard/Volusia County lie to the Volusia/Flagler County line in Florida.

The eye and the core of Hurricane Matthew remained over the Atlantic Ocean as Matthew moved parallel to the east coast of Florida.  Occasionally, the western side of the eyewall would move over the coast and bring stronger winds to those areas.  The remnants of the smaller inner eyewall dissipated during the afternoon.  Once the eyewall cycle was completed the remaining outer eyewall began to contract.  Thunderstorms around the eye generated enough upper level divergence to pump out mass and limited the increase of the surface pressure.  As a result, a strong pressure gradient force is still producing winds of over 100 m.p.h. (160 km/h) in the north and northeastern parts of the eyewall.

Hurricane Matthew has been moving around the western end of a subtropical high pressure system which steered the hurricane toward the north on Friday.  An upper level trough over the Central U.S. will move east and southwesterly winds with the trough will start to steer Matthew toward the northeast later tonight.  It is not clear exactly when the turn will occur and the exact timing of the turn to the northeast is very important.  If Hurricane Matthew continues to move north, the northern eyewall which contains the strongest winds could reach Savannah and the coast of South Carolina in 6-10 hours.  If those winds reach the coast, then the damage will be more severe.  If Hurricane Matthew turns northeast before the northern eyewall reaches the coast, then the damage will be less.

Even though Hurricane Matthew weakened slightly to a Category 2 hurricane and is no longer officially a major hurricane, it is still capable of causing regional serious damage.  Matthew will cause wind damage and widespread power outages along the coasts of Georgia and South Carolina, even if the center of the eye does not officially make landfall.  If the center of the eye brings the northern eyewall over the coast, the winds will be much stronger and the damage will be greater.  In addition, easterly winds on the northern side of Hurricane Matthew will drive water toward the coast and create serious storm surges.  In places where the shape of the coast funnels water into smaller areas, the surges will be even more dangerous.

Hurricane Matthew Develops Concentric Eyewalls on Its Way Toward Florida

The structure of Hurricane Matthew changed on Thursday as it strengthened on its way toward Florida.  A second larger outer eyewall formed around the small tight inner eye and eyewall.   At 5:00 p.m. EDT on Thursday the center of Hurricane Matthew was located at latitude 26.2°N and longitude 78.6°W which put it about 25 miles (40 km) south-southeast of Freeport, Bahamas and about 100 miles (160 km) east-southeast of West Palm Beach, Florida.  Matthew was moving toward the 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 938 mb.  Hurricane Matthew was a Category 4 hurricane on the Saffir-Simpson Scale.

A Hurricane Warning is in effect for the portion of the coast from Golden Beach, Florida to South Santee River, South Carolina including Lake Okeechobee.  A Tropical Storm Warning is in effect for the portion of the coast South Santee River, South Carolina to Surf City, North Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Anclote River, Florida to Suwanee River.  A Tropical Storm Warning is in effect for the portion of the coast from Chokoloskee to Golden Beach, Florida and for the Florida Keys from Seven Mile Bridge eastward including Florida Bay.  A Tropical Storm Watch has been issued for the portion of the coast from Chokoloskee, Florida to Anclote River.  A Hurricane Warning is in effect for the northwestern Bahamas including the Abacos, Andros Island, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.

Hurricane Matthew began to strengthen early on Thursday morning.  The minimum surface pressure decreased from 961 mb at 11:00 p.m. EDT on Wednesday night to 940 mb at 8:00 a.m. EDT on Thursday morning.  A decrease of 17 mb in nine hours is a very rapid pressure fall, but the maximum wind speed only increased from 115 m.p.h. ((185 km/h) to 125 m.p.h. (205 mk/h) during that time period.  The rapid decrease in pressure and the increase in the pressure gradient force around the center of Hurricane Matthew contributed to the reformation of a small circular eye at the center of the hurricane.  Once the new eyewall was established, the wind speed increased to 140 m.p.h. (225 km/h) within three hours.

The structure of the circulation of Hurricane Matthew continued to improve during the day on Thursday as the hurricane moved over the very warm water around the Bahamas.  A circular inner eye with a diameter of 18 miles (29 km) was surrounded by a ring of strong thunderstorms.  A rainband wrapped all the way around the original eye and eyewall and a second outer eyewall formed.  The outer eyewall has a diameter of 70 miles (105 km).  The strongest winds in Hurricane Matthew are occurring in the inner eyewall.  Hurricane Matthew has maintained a double eyewall structure in recent hours.

Matthew is moving through an environment that is favorable for hurricanes.  The Sea Surface Temperature is near 30°C.  There upper level winds are weak and there is not much vertical wind shear.  Hurricane Matthew is likely to maintain its current intensity as long as the inner eyewall remains intact.  If the inner eye starts to dissipate, then the strongest winds would be found in the outer eyewall, but those winds are not as strong as the winds in the inner eyewall.  So the intensity of Hurricane Matthew would decrease if that happened.  However, the wind field of a hurricane typically gets larger if the outer eyewall becomes the strongest part of the circulation.

Hurricane Matthew is moving around the western end of a subtropical high pressure system which is steering it toward the northwest and that general motion is expected to continue until the hurricane gets close to the coast of Florida.  When Hurricane Matthew gets close to the coast, it will be at the western end of the high and the hurricane will turn north.  It is still unclear if the turn will occur just before Matthew reaches the coast or whether it will occur after the center of Matthew moves on shore.  Eventually, when Hurricane Matthew moves farther north, an upper level trough approaching form the west will steer it toward the northeast, but the timing of that turn is still uncertain too.

The future track of Hurricane Matthew will be a critical factor in determining the damage it causes.  If Matthew turns north before it reaches the east coast of Florida, the the strongest winds would stay over the Atlantic Ocean.  The same holds true for the turn toward the northeast.  If the turn occurs before Hurricane Matthew reaches Georgia and South Carolina, then the strongest winds would stay offshore.  A much more destructive scenario would unfold if Hurricane Matthew reaches the coast of Florida and then turns north.  If Matthew grinds its way north along the coast, the strongest winds and highest storm surge would occur.  Matthew could move over cities like Daytona Beach and Jacksonville.  If the turn to the northeast is delayed, then Matthew would also move near Savannah, Georgia and Charleston, South Carolina.

The Hurricane Intensity Index (HII) for Hurricane Matthew is 28.2.  The Hurricane Size Index (HSI) is 18.4 and the Hurricane Wind Intensity Size Index (HWISI) is 46.6  The indices indicate that Hurricane Matthew is stronger than Hurricanes Frances and Jeanne were when they hit southeast coast of Florida in 2004.  Matthew is smaller than Frances and Jeanne were in 2004.  The HWISI for Matthew is similar to the ones for Frances and Jeanne, which would suggest that Matthew is capable of causing similar damage.  Hurricane Frances cause 11 billion dollars of damage in 2004.  Hurricane Jeanne caused about 8 billion dollars of damage.  So, Hurricane Matthew has the potential to be a very destructive hurricane, but the damage it does will be determined by its ultimate path.  Matthew will do much less damage if the core of the hurricane stays offshore.

Hurricane Matthew will bring gusty winds and heavy rain to the southeast coast of Florida on Thursday night.  It will do the same to the northeast coast of Florida on Friday.  Strong easterly winds on the northern side of the center of circulation will drive water toward the shore and create dangerous storm surges as Hurricane Matthew moves along the coast.  The heavy rain is likely to cause fresh water flooding in some locations.  Hurricane Matthew could have the greats impact on the coasts of Georgia and South Carolina on Friday night and Saturday.

Hurricane Matthew Moves Across the Bahamas Toward Florida

Hurricane Matthew moved away from Cuba and across the Southeastern Bahamas on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Matthew was located at latitude 23.4°N and longitude 76.4°W which put it about 125 miles (205 km) south-southeast of Nassau, Bahamas and about 325 miles (525 km) southeast of West Palm Beach, Florida.  Matthew was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 135 m.p.h. (220 km/h).  The minimum surface pressure was 961 mb.  Hurricane Matthew was a Category 3 hurricane on the Saffir-Simpson Scale.

A Hurricane Warning is in effect for the portion of the coast from Golden Beach, Florida to Fernandina Beach including Lake Okeechobee.  A Hurricane Watch has been issued for the portion of the coast of Florida from Fernandina Beach to Edisto Beach, South Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Chokoloskee to Golden Beach, Florida and for the Florida Keys from Seven Mile Bridge eastward including Florida Bay.  A Tropical Storm Watch has been issued for the portion of the coast from Chokoloskee, Florida to Suwanee River.  Hurricane Warnings are also in effect for the Southeastern Bahamas including the Inaguas, Mayaguana, Acklins, Crooked Island, Long Cay, Ragged Island, and for the Central Bahamas including Long Island, Exuma, Rum Cay, San Salvador and Cat Island.  A Hurricane Warning is in effect for the northwestern Bahamas including the Abacos, Andros Island, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.

Hurricane Matthew weakened after it passed over southwestern Haiti and the eastern end of Cuba.  The structure of the eyewall deteriorated on Wednesday morning, when the core of Hurricane Matthew started to move north of Cuba.  After a few hours over the warm water around the Bahamas, a circular eyewall began to reform around the center of circulation.  The eyewall appeared to weaken for a time on Wednesday afternoon, but it then became much more well organized around a distinct eye appeared on Wednesday night.  The loss of organization around the eye resulted in a decrease in the maximum sustained wind speed to 115 m.p.h. and an increase in the  minimum surface pressure to 964 mb.

Hurricane Matthew appeared to be intensifying on Wednesday night.  A reconnaissance aircraft observed a minimum surface pressure that was several millibars lower and the structure of the core of the hurricane was displaying more organization.  Thunderstorms around the eye of Hurricane Matthew were beginning to generate stronger upper level divergence which was pumping mass out in all directions.  The divergence was allowing the surface pressure to decrease as measured by the recon plane.

Hurricane Matthew is moving through a very favorable environment.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is little vertical wind shear.  As the minimum pressure decrease, the pressure gradient force will accelerate the air faster and the wind speeds will increase.  Hurricane Matthew could become a Category 4 hurricane on Thursday and there is a chance it could get near Category 5.

A ridge of high pressure is steering Matthew toward the northwest and that general motion is expected to continue on Thursday.  The center of strong hurricanes sometimes wobble a bit from side to side in response to bursts of thunderstorms in the eyewall, but the general motion is likely to be toward the northwest.  The center of Hurricane Matthew is passing just west of the Exumas in the Bahamas.  Matthew is likely to pass near Nassau on New Providence and near Andros Island on Thursday morning.

On its anticipated track Hurricane Matthew could be very near the southeast coast of Florida by Thursday evening.  Matthew could make landfall in the portion of the coast between Fort Lauderale and West Palm Beach or the center could stay just offshore.  The center of Hurricane Matthew is forecast to move along the east coast of Florida on Friday.  An upper level trough approaching from the west is expected to turn Hurricane Matthew toward the northeast on Friday night or Saturday.  However, the timing and location of that turn is still uncertain.  It could occur near the coast of Georgia and South Carolina or it could occur a little sooner and move the center of Matthew back over the Atlantic Ocean.

Hurricane Matthew poses a serious potential risk to the southeast coast of the U.S.  The Hurricane Intensity Index (HII) is 20.6.  The Hurricane Size Index (HSI) is 15.7 and the Hurricane Wind Intensity Size index (HWISI) is 36.3.  Those indices indicate that Matthew will be capable of causing regional wind damage.  Matthew could get bigger and stronger before it reaches Florida, which would increase the risk.  If Matthew tracks along the coast or just inland, will bring hurricane force winds to the populated areas on the east coast of Florida.  In addition, strong easterly winds north of the center of Hurricane Matthew will blow water toward the coast and create the potential for dangerous storm surges.  Matthew will move slowly enough that locally heavy rain could fall and fresh water flooding could also create problems.

Hurricane Matthew Crosses Southwest Haiti, Watches Issued for Florida

Hurricane Matthew crossed the western end of the Tiburon Peninsula of Haiti on Tuesday morning.  The eye emerged intact over the Golfe de la Gonave and the center of Hurricane Matthew is about half way between Haiti and the eastern end of Cuba.  At 2:00 pm. EDT on Tuesday the center of Hurricane Matthew was located at latitude 19.4°N and longitude 74.3°W which put it about 65 miles (105 km) east-southeast of Guantanamo, Cuba.  Matthew was moving toward the north at 10 m.p.h. (16 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 949 mb.

A Hurricane Watch has been issued for the portion of the coast of Florida from Deerfield Beach to the Volusia/Brevard County line.  A Tropical Storm Watch has been issued from Seven Mile Bridge in the Florida Keys to Deerfield Beach.  Hurricane Warnings are in effect for Haiti and the Cuban provinces of Guantanamo, Santiago de Cuba, Holguin, Granma and Las Tunas.  Hurricane Warnings are also in effect for the Southeastern Bahamas including the Inaguas, Mayaguana, Acklins, Crooked Island, Long Cay, Ragged Island, and for the Central Bahamas including Long Island, Exuma, Rum Cay, San Salvador and Cat Island.  A Hurricane Warning is in effect for the northwestern Bahamas including the Abacos, Andros Island, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  A Hurricane Watch has been issued for the Cuban province of Camaguey.  A Tropical Storm Warning is in effect for the Turks and Caicos and the south coast of the Dominican Republic from Barahona to Haiti.  Tropical Storm Watches have been issued for the northern coast of the Dominican Republic from Puerto la Plata to Haiti.

Even after passing over the mountains of the Massif de la Hotte on the southwestern peninsula of Haiti, the structure of Hurricane Matthew remained well organized.  Matthew has a circular eye with a diameter of 24 miles (39 km).  The eye is surrounded by a ring of strong thunderstorms.  The wind field around Hurricane Matthew actually expanded after it crossed southwestern Haiti.  Winds to hurricane force extend out about 60 miles (95 km) from the center of circulation.  Thunderstorms around the eye are generating upper level divergence which is pumping out mass in all directions.  Additional rainbands are rotating around the core of Matthew.

Hurricane Matthew is moving through a very favorable environment.  It is moving over water where the Sea Surface Temperature is 30°C.  The winds in the upper levels are weak and the is little vertical wind shear.  Hurricane Matthew could weaken slightly when the center passes over eastern Cuba, but it will likely restrengthen when it moves over the very warm water around the Bahamas.  Matthew is likely to remain a Category 4 hurricane on the Saffir-Simpson Scale. and it could become a Category 5 hurricane while it is moving over the Bahamas.  Hurricane Joaquin almost reached Category 5 while it was near the Bahamas in early October last year.

Matthew is moving around the western end of subtropical high pressure system, which is steering the hurricane toward the north.  That general motion is expected to continue for another 12 hours or so.  The high is expected to strengthen and extend west on Wednesday.  When that happens, Hurricane Matthew will be steered more toward the northwest.  On its anticipated track Hurricane Matthew will move across the eastern end of Cuba later on Tuesday and across the Bahamas on Wednesday.  Hurricane Matthew could be very near the east coast of Florida on Thursday.  Matthew could come very close to the coast of South Carolina on Friday and it could be near the coast of North Carolina on Saturday morning.  It is still not clear if the eye of Hurricane Matthew will reach landfall in any of those places.

The Hurricane Intensity Index (HII) for Matthew is 29.8.  The Hurricane Size Index (HSI) is 19.5 and the Hurricane Wind Intensity Size Index (HWISI) is 49.3.  Those indices mean that Hurricane Matthew is capable of causing regional significant wind damage.  Matthew will also generate a significant storm surge over eastern Cuba and the Bahamas.  Water level rises will occur along the southeast coast of the U.S. where easterly winds push the water toward the shore.  Hurricane Matthew is stronger, but a little smaller than Hurricane Jeanne was in 2004, when Jeanne made landfall on the coast of Florida.

Hurricane Matthew Moves Toward Haiti, Threat to U.S. Increases

Hurricane Matthew moved toward Haiti on Monday and the threat to the U.S. increased.  At 5:00 pm. EDT on Monday the center of Hurricane Matthew was located at latitude 16.3°N and longitude 74.7°W which put it about 140 miles (220 km) south of Tiburon, Haiti.  Matthew was moving toward the north at 7 m.p.h. (11 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. (265 km/h).  The minimum surface pressure was 940 mb.

Hurricane Warnings are in effect for Haiti and the Cuban provinces of Guantanamo, Santiago de Cuba, Holguin, Granma and Las Tunas.  Hurricane Warnings are also in effect for the Southeastern Bahamas including the Inaguas, Mayaguana, Acklins, Crooked Island, Long Cay, Ragged Island, and for the Central Bahamas including Long Island, Exuma, Rum Cay, San Salvador and Cat Island.  Hurricane Watches have been issued for the Cuban province of Camaguey and the northwestern Bahamas including the Abacos, Andros Island, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence, and for the Turks and Caicos.  A Tropical Storm Warning is in effect for Jamaica and the south coast of the Dominican Republic from Barahona to Haiti.  Tropical Storm Watches have been issued for the northern coast of the Dominican Republic from Puerto la Plata to Haiti.

The structure of Hurricane Matthew is well organized.  It has a circular eye with a diameter of 18 miles (29 km).  The eye is surrounded by a ring of strong thunderstorms.  Winds to hurricane force extend out about 40 miles (65 km) from the center of circulation.  Thunderstorms around the eye are generating upper level divergence which is pumping out mass in all directions.  Additional rainbands are rotating around the core of Matthew.

The Hurricane Intensity Index (HII) for Matthew is 28.2.  The Hurricane Size Index (HSI) is 15.1 and the Hurricane Wind Intensity Size Index (HWISI) is 43,3.  These indices suggest that Hurricane Matthew is capable of causing regional significant wind damage to Haiti.  Hurricane Matthew is very similar in size and intensity to what Hurricane Dennis was when Dennis hit northwest Florida in 2005.  Hurricane Matthew is stronger and a little bigger than Hurricane Sandy was when Sandy was over the northwestern Caribbean Sea in 2012.

Hurricane Matthew is moving through a very favorable environment.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is not much vertical wind shear.  Matthew is likely to maintain its intensity as it moves toward Haiti.  If a rainband wraps around the eye, then an eyewall replacement cycle could cause temporary fluctuations in intensity.  The future path of Matthew could have a big impact on the intensity of the hurricane.  If the center of Matthew moves over southwestern Haiti, then the Massif de la Hotte could seriously disrupt the lower levels of the circulation.  Mountains in Massif de la Hotte extend up to 7700 feet (2347 meters).  On the other hand, if the eye and eyewall move just west of Haiti, then the inner core is likely to remain intact.  The water around the Bahamas is very warm and if the core of Hurricane Matthew is reasonably intact when it gets there, Matthew will likely regain its intensity.

Hurricane Matthew is moving around the southwestern end of a subtropical high pressure system, which has allowed the hurricane to move just east of due north.  That general motion is expected to continue for another day or so.  In about 24 hours the subtropical high is expected to strengthen and extend westward.  If the high does strengthen, it will force Hurricane Matthew to move more toward the northwest.  Guidance from numerical models has supported this scenario today.  The northwest motion could take Hurricane Matthew over the Central and Northwestern Bahamas during the middle of the week.  A northwesterly track could bring Hurricane Matthew close to Florida on Thursday and near the Mid-Atlantic Coast on Friday.  Based on guidance from the forecast models, the threat to the U.S. increased significantly on Monday.

Hurricane Matthew has the potential to cause regional significant wind damage to Haiti.  Even if the center moves west of Haiti, Matthew will produce very heavy rain and the potential for devastating flash floods and mudslides exists.  There will also be significant storm surges along the coasts of Haiti, the Dominican Republic and eastern Cuba.

Tropical Storm Julia Edges Farther from the Southeast U.S.

Tropical Storm Julia moved slowly eastward on Thursday which took it farther from the Southeastern coast of the U.S.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Julia was located at latitude 32.1°N and longitude 77.1°W which put it about 150 miles (245 km) south-southeast of Wilmington, North Carolina.  Julia was moving toward the east at 8 m.p.h. (13 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 1007 mb.

The circulation of Tropical Storm Julia is not well organized.  All of the stronger thunderstorms are well to the east of the center of circulation.  The broad low level circulation is elongated from the west-southwest of the east-northeast.  There are no thunderstorms close to the center of circulation.

Tropical Storm Julia is in an environment that is unfavorable for intensification.  It is moving over water where the Sea Surface Temperature is near 29°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, upper level westerly winds are causing strong vertical wind shear.  The upper level winds have at least temporarily blown the upper part of the circulation east of the lower third of the circulation.  As long as the upper level winds are as strong as they are now, Tropical Storm Julia will slowly weaken.  If the upper level winds slow down, then more thunderstorms could develop near the center and Julia could get a little stronger.  With the current strong vertical wind shear Tropical Storm Julia should slowly weaken during the next few hours.

The vertical structure of Tropical Storm Julia maintained enough integrity that the westerly winds pushed the thunderstorms toward the east and they dragged the low level center with them.  However, it now appears that the vertical parts of the circulation have separated.  The low level circulation is being steered slowly back toward the southwest by a surface high pressure system to the north of Julia.  Tropical Storm Julia could move erratically during the next several days.  As long as no thunderstorms form near the center, it will drift slowly toward the southwest.  Any time thunderstorms form near the center of circulation, the taller storm will be pushed toward the east.

Tropical Storm Julia Forms over Northeast Florida

Although tropical storms normally form over an ocean, Tropical Storm Julia formed over northeast Florida on Tuesday.  The National Hurricane Center (NHC) had tracked a tropical disturbance from Africa across the Atlantic Ocean to Florida.  NHC had designated the system as Invest 93L for tracking purposes.  Although the disturbance moved over the Florida peninsula on Monday, a distinct center of circulation developed at the surface on Tuesday while the disturbance moved north over the northeastern part of Florida.  An area of stronger thunderstorms formed over the Atlantic Ocean east of the center of circulation on Tuesday afternoon and persisted into Tuesday evening.  Because the system had a distinct surface center, persistent thunderstorms and winds to tropical storm force, the National Hurricane Center named it Tropical Storm Julia at 11:00 p.m. EDT on Tuesday and initiated advisories on the Julia.

At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Julia was located at latitude 30.3°N and longitude 81.6°W which put it about 5 miles (10 km) west of Jacksonville, Florida.  Julia was moving toward the north-northwest at 9 m.p.h. (15 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 1009 mb.

A Tropical Storm Warning has been issued for the portion of the coast from Ponte Vedra Beach, Florida to Altamaha Sound, Georgia.

The circulation of Tropical Storm Julia is very asymmetrical.  Most of the thunderstorms and rain are north and east of the of circulation.  There are few storms or rain west and south of the center.  One primary rainband extends part of the way around the southeastern portion of the circulation.  The thunderstorms to the east of the center are generating upper level divergence which is pumping out mass to the northeast of the circulation.

Since the center of Tropical Storm Julia is over land, intensification would normally be unlikely.  However, about half of the circulation is over water where the Sea Surface Temperature is near 28.5°C.  In addition, the atmospheric environment is favorable for strengthening.  The upper level winds are not too strong and the vertical wind shear is moderate.  It is possible that the wind speeds could increase in the thunderstorms in the part of the circulation that is over the Atlantic Ocean on Wednesday.

The steering currents around Tropical Storm Julia are quite complicated.  There is an upper low over the Gulf of Mexico, a ridge over the western Atlantic Ocean and an upper level trough moving toward the Great Lakes and East Coast of the U.S.  The upper low and ridge over the western Atlantic combined to steer Julia mainly toward the north-northwest on Tuesday.  At times the asymmetric circulation and the upper level divergence to the east of the circulation caused the center to move east as well.  It is likely that this motion will continue on Wednesday.  The center of Julia could move very close to the coast of Georgia.  If the center remains inland, then Tropical Storm Julia will start to weaken slowly.  If the center moves over the water, then it could intensify and persist longer.

The primary risk posed by Tropical Storm Julia will be locally heavy rain and the potential for flash flooding.  Winds and waves along the coast will cause rip currents and some beach erosion.  Water rises of several feet (one meter) will be possible.

Hurricane Hermine Making Landfall in North Florida

After intensifying into a hurricane on Thursday, Hurricane Hermine is making landfall near St. Marks, Florida.  At midnight EDT the center of Hurricane Hermine was located at latitude 29.8°N and longitude 84.2°W which put it about 20 miles (30 km) south of St. Marks, Florida.  Hermine was moving toward the north-northeast at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 984 mb.

A Hurricane Warning is in effect from Suwannee River to Mexico Beach, Florida.  A Hurricane Watch is in effect from Anclote River to Suwannee River and from Mexico Beach to the Walton County/Bay County line.  A Tropical Storm Warning is in effect from Englewood to Suwannee River and from Mexico Beach to the Walton County/Bay County line.  A Tropical Storm Warning is also in effect from the Flagler County/Volusia County line to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Watch is in effect from Duck, North Carolina to Sandy Hook, New Jersey including the Chesapeake Bay from Smith Point southward and southern Delaware Bay.

The circulation of Hurricane Hermine organized quickly on Thursday.  It developed an eye with a mostly complete eyewall.  Spiral rainbands developed with strong winds in the eastern half of the circulation.  Upper level divergence to the east of Hermine pumped out mass and allowed the surface pressure to decrease.  The circulation is still asymmetrical with most of the stronger winds east of the center, but it looks a lot more typical of hurricanes that move toward the northern coast of the Gulf of Mexico.

Hurricane Hermine will weaken after it makes landfall.  It could interact with a cold front moving into the southeastern U.S.  It is possible that Hermine could develop a hybrid structure that is part tropical and part extratropical.  Hermine could have winds to tropical storm force as it passes over the Mid-Atlantic coast.  The stronger winds are likely to be out over the Atlantic Ocean and winds should be weaker farther inland.

An upper level trough is steering Hurricane Hermine toward the north-northeast and a general northeasterly motion is expected to continue for another 36 hours.  Later in the weekend a surface high pressure system could move north of Hermine and stall its progress.  Hermine could be stationary for a time.  On its anticipated track center of Hermine is likely to pass east of Tallahassee, Florida.  The center could pass north of Savannah, Georgia before coming near Charleston, South Carolina.  Hermine is likely to move near Cape Hatteras, North Carolina and out into the Atlantic Ocean.

Hurricane Hermine is capable of causing regional minor wind damage.  It is likely to cause widespread power outages.  The coast of the northeastern Gulf of Mexico is susceptible to storm surges and high water will effect that area overnight.  Locally heavy rainfall will create the potential for flooding.  When rainbands move ashore, wind shear could spin up tornadoes.  As Hermine moves near the Mid-Atlantic coast, easterly winds could cause water rises.

The Hurricane Intensity Index (HII) for Hurricane Hermine is 11.5.  The Hurricane Size Index (HSI) is 14.0.  The Hurricane Wind Intensity SIze Index (HWISI) is 25.5.  These indices are very similar to the ones for Hurricane Isaac before it hit the coast of Louisiana n 2012.  The HII for Isaac was 11.5.  Its HSI was 16.7 and its HWISI was 28.2.  This means that Hurricane Hermine is as strong and just smaller than Hurricane Isaac was just before it made landfall.  Hurricane Isaac did hit a more populated and more built up region.  Hurricane Isaac did 970 million dollars worth of insured damage.  It caused 407 million dollars to be paid out for flood insurance.  It is estimated that Hurricane Isaac caused 2.35 billion dollars worth of damage in the U.S.