Tag Archives: the Bahamas

Tropical Depression Four Develops East of the Lesser Antilles

Tropical Depression Four developed east of the Lesser Antilles on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Four was located at latitude 12.8°N and longitude 38.4°W which put it about 1545 (2485 km) east of the Lesser Antilles.  The depression was moving toward the west-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1009 mb.

A larger area of thunderstorms formed and persisted on the western side of a tropical disturbance formerly designated as Invest 94L on Wednesday and the National Hurricane Center classified the system as Tropical Depression Four.  The distribution of thunderstorms is still asymmetrical.  Most of the stronger storms are developing in the western half of the circulation.  The thunderstorms in the western part of the circulation were beginning to generate upper level divergence.  There were few thunderstorms in the eastern half of the depression and the vertical structure of the circulation could be tilted to the west with height.

Tropical Depression Four will be moving through an environment that contains both positive and negative factors for intensification.  The depression will move over water where the Sea Surface Temperature is near 27°C.  So, there is sufficient energy in the upper ocean to support intensification.  An upper level ridge is producing easterly winds which are blowing toward the top of the circulation.  Those winds could be causing the circulation to tilt toward the west with height.  Moderate vertical wind shear could inhibit intensification.  Drier air is north of the tropical depression.  If the depression remains south of the drier air and if the vertical wind shear does not become too strong, then the depression could strengthen.  Alternatively, if the depression pulls in drier air and/or the vertical shear increases, then the depression could weaken back to a tropical wave.

The subtropical ridge over the Atlantic Ocean is steering Tropical Depression Four toward the west-northwest.  A general west-northwesterly motion is expected for the next several days.  The actual track will also have a significant effect on the future intensity of Tropical Depression Four. If the depression moves on a more southerly track, it will stay south of the drier air and it would have a greater opportunity to intensify.  If the depression moves farther to the north, it will move into the drier air and will be more likely to weaken,

Invest 94L Likely to Develop East of Lesser Antilles

A tropical disturbance currently designated as Invest 94L is likely to develop into a tropical cyclone east of the Lesser Antilles.  The National Hurricane Center’s probability of formation of a tropical cyclone from this system during the next five days is 70%.  At 2:00 p.m. EDT on Monday the center of Invest 94L was located at latitude 8.7°N and longitude 32.7°W which put it about 1830 miles (2950 km) east of the Lesser Antilles.  It was moving toward the west at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1011 mb.

Invest 94L consists of a broad area of low pressure, but it has not developed a well organized inner core.  The initial area of low pressure consisted of a counterclockwise rotation associated with a tropical wave that moved over the eastern Atlantic Ocean.  The initial low slowed down as it was moving westward and a second tropical wave caught up to it.  The thunderstorms from the two waves appear to be merging into a single system.  An area of showers and thunderstorms on the northern and western sides of the surface low was part of the first tropical wave.  Other bands of showers and thunderstorms south and east of the low are associated with the second tropical wave.  If the broad low pressure system can collect the rotation from the two tropical waves, it could strengthen the surface low.

Invest 94L will move through an environment that will be favorable for the development of a tropical cyclone.  It will move over water where the Sea Surface Temperature (SST) is near 28°C.  There are easterly winds blowing at multiple levels in the atmosphere and there is little vertical winds shear.  The existence of a surface low pressure system, warm SSTs and little vertical wind shear are the primary ingredients for the development of a tropical cyclone.  That is the reason why there is strong probability that Invest 94L will develop into a tropical depression or a tropical storm.

Invest 94L will be steered by the subtropical high pressure system over the Atlantic Ocean.  A general westerly or west-northwesterly track is forecast during the next few days.  There is still significant uncertainty about the ultimate track and intensity of this system beyond that time frame.  It will need to be monitored closely as it moves west.

Low Pressure Develops East of the Bahamas

An area of low pressure developed east of the Bahamas and the system was designated as Invest 90L on Sunday afternoon.  At 5:00 p.m. EDT on Sunday the center of Invest 90L was located at latitude 24.0°N and longitude 71.0°W which put it about 260 miles (420 km) east of the Bahamas.  Invest 90L was moving toward the northwest at 11 m.p.h. (17 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.

The circulation of Invest 90L consists of a large asymmetrical low pressure system.  Most of the showers and thunderstorms are occurring northeast of the center of circulation.  Those showers and thunderstorms are being generated by convergence of winds from a large high pressure system over the north Atlantic Ocean into the area of low pressure.  A swirl of low clouds has emerged on the southwestern side of the low, but it is unclear if this is the actual center of circulation or is just a transient mesoscale feature.  A strong pressure gradient between the high pressure system and the low is producing an area of winds to tropical storm force northeast of the center of the low.  The winds are weaker in other parts of the circulation.

Invest 90L is in an environment that is mostly unfavorable for tropical cyclones.  It is moving over water where the Sea Surface Temperature is near 25°C.  So, there is less energy in the upper ocean to support tropical development.  An upper level trough over the southeastern U.S. is producing strong southwesterly winds which are blowing across the top of Invest 90L.  Those winds are producing strong vertical wind shear.  Marginal Sea Surface Temperatures and strong vertical wind shear make the classical development of a tropical cyclone unlikely.  However, the temperature in the upper troposphere is also cold and there may be enough instability in the atmosphere to produce thunderstorms.  If the wind shear decrease, then more thunderstorms could develop closer to the center of circulation and a subtropical cyclone could form.

The high over the north Atlantic is blocking northward movement of Invest 90L and the high is steering it toward the northwest.  A general northwesterly motion is expected to continue for another day or so.  Eventually the high will move off to the east and Invest 90L will start to move toward the northeast.  On its anticipated track Invest 90L will stay east of the U.S. and the Bahamas.  Invest 90L could pass close to Bermuda and it has the potential to bring gusty winds.

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.

Hurricane Matthew Moving Slowly North Toward the Greater Antilles

Powerful Hurricane Matthew was moving slowly north over the Northwestern Caribbean Sea on Sunday night.  At 11:00 p.m. EDT on Sunday the center of Hurricane Matthew was located at latitude 14.7°N and longitude 75.0°W which put it about 255 miles south-southeast of Kingston, Jamaica.  Matthew was moving toward the north at 5 m.p.h. (8 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 943 mb.

Hurricane Warnings are in effect for Haiti, Jamaica, 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 and Ragged Island.  A Hurricane Watch has been issued for the Cuban province of Camaguey, the Central Bahamas and the Turks and Caicos.  A Tropical Storm Warning is in effect for the south coast of the Dominican Republic from Barahona to the border with Haiti.  A Tropical Storm Watch has been issued for the north coast of the Dominican Republic from Puerto la Plata to the border with Haiti.

Matthew is a very well organized symmetrical hurricane.  There is a circular eye with a diameter of about 14 miles (22 km).  The eye is surrounded by a ring of strong thunderstorms.  Numerous bands of thunderstorms are rotating around the core of the circulation.  The thunderstorms are generating well developed upper level divergence which is pumping out mass.

The Hurricane Intensity Index (HII) is 29.9.  The Hurricane Size index (HSI) is 10.4 and the Hurricane Wind Intensity Size Index (HWISI) is 40.3.  The indices indicate that Hurricane Matthew is as strong as Hurricane Dennis was in 2005, but Matthew is a little smaller than Dennis was.

Hurricane Matthew will be moving through a very favorable environment.  Matthew will be moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  There could be some fluctuations in intensity, especially if eyewall replacement cycles occur.  Matthew is likely to remain a powerful hurricane.

Hurricane Matthew has reached the western end of a subtropical high pressure system.  Matthew is likely to continue to move north around the western end of the subtropical high.  On its anticipated track Hurricane Matthew could be near Jamaica and western Haiti on Monday night.  Matthew could reach eastern Cuba on Tuesday and it could be over the Bahamas on Wednesday.

Hurricane Matthew is capable of causing region significant wind damage.  It will bring locally heavy rain to parts of Haiti, Jamaica and Cuba.  Matthew will also create dangerous storm surges along the coast.

Powerful Hurricane Matthew Turns Northwest

After completing a tight slow cyclonic loop near the northern coast of Colombia, Hurricane Matthew started moving toward the northwest on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Matthew was located at latitude 13.8°N and longitude 73.6°W which put it about 360 miles (580 km) southeast of Kingston, Jamaica.  Matthew was moving toward the north-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 940 mb.

A Hurricane Warning has been issued for Jamaica.  A Hurricane Warning is in effect for the coast of Haiti from the southern border with the Dominican Republic to Le Mole St. Nicholas.  A Hurricane Watch is in effect from Le Mole St. Nicholas to the northern border with the Dominican Republic.  A Hurricane Watch is also in effect for Cuba from Camaguey province to Guantanamo province.

Matthew is a compact hurricane.  It has a circular eye with a diameter of less than 10 miles (16 km).  The eye is surrounded by a tight ring of strong thunderstorms and the strongest winds are occurring in that ring.  Additional rainbands are rotating around the core of the circulation.  Thunderstorms in the core are generating upper level divergence which is pumping out mass to the east of Hurricane Matthew.

The Hurricane Intensity Index (HII) is 31.6.  The Hurricane Size Index (HSI) is 10.3 and the Hurricane Wind Intensity Size index (HWISI) is 41.9.  The indices indicate that Hurricane Matthew is as intense and a little smaller than Hurricane Dennis was when Dennis was over the northwestern Caribbean Sea in 2005.

Hurricane Matthew will continue to move through a favorable environment on Sunday.  It will move over water where the Sea Surface Temperature is near 30°.  An upper level trough west of Matthew will generate southwesterly winds which will blow near the northwestern part of the hurricane.  Although there will be some vertical wind shear, it may not have a significant impact on Hurricane Matthew.  If one of the rainbands wraps around the existing eye, then an eyewall replacement cycle could cause a temporary weakening of Hurricane Matthew.

Hurricane Matthew is moving around the western end of a subtropical high pressure system.  The combination of the subtropical high and the upper level trough to the west of Matthew should steer the hurricane toward the north-northwest on Sunday.  On its anticipate track Hurricane Matthew could reach Jamaica and southern Haiti on Monday afternoon.  Matthew could reach eastern Cuba on Monday night and it could be over the southeastern Bahamas on Tuesday.

Hurricane Matthew is a dangerous hurricane.  The indices suggest that it is capable of causing significant regional wind damage.  It could also bring flooding rains to parts of Haiti.  Hurricane Matthew could also produce dangerous storm surges on the south coasts of Haiti, Jamaica and Cuba.

Hurricane Matthew Becomes the First Category 5 Atlantic Hurricane Since 2007

Hurricane Matthew continued its rapid intensification on Friday night and it became the first Atlantic hurricane to reach Category 5 on the Saffir-Simpson Scale since Hurricane Felix did so in 2007.  At 11:00 p.m. EDT on Friday the center of Hurricane Matthew was located at latitude 13.3°N and longitude 72.3°W which put it about 440 miles (710 km) southeast of Kingston, Jamaica.  Matthew was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 941 mb.

The Hurricane Intensity Index (HII) for Matthew was 35.0.  The Hurricane Size Index (HSI) was 13.7 and the Hurricane Wind Intensity Size Index (HWISI) was 48.7.  These indices indicate that Hurricane Matthew is not as intense and slightly smaller than Hurricane Wilma was, when Wilma was a Category 5 hurricane over the northwestern Caribbean Sea in 2005.

A Hurricane Watch is in effect for Jamaica.  A Tropical Storm Watch is in effect for the portion of the coast from the Haiti/Dominican Republic border to Port-Au-Prince, Haiti.  A Tropical Storm Warning is in effect for the portion of the coast from the Colombia/Venezuela border to Riohacha, Colombia.

Hurricane Matthew remains in a very favorable environment of minimal vertical wind shear and warm Sea Surface Temperatures.  The intensity may fluctuate as a result of eyewall replacement cycles.

A strong subtropical high is steering Hurricane Matthew toward the west.  Matthew is slowing as it approaches the western end of the subtropical high.  It will turn toward the north when it reaches the western end of that high pressure system.  However, the location, time and sharpness of the turn to the north are still uncertain.  That uncertainty means that the longer term track of Hurricane Matthew is also uncertain.  We should get more clarity about the future direction of Hurricane Matthew during the next several days.