Category Archives: Tropical Cyclones

Information about tropical cyclones

Hurricane Melissa Nears Jamaica

The core of Hurricane Melissa was nearing southwestern Jamaica on Tuesday morning.  At 10:00 a.m. EDT on Tuesday the center of Hurricane Melissa was located at latitude 17.7°N and longitude 78.1°W which put the center about 45 miles (75 km) south-southeast of Negril, Jamaica.  Melissa was moving toward the north-northeast at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 185 m.p.h. (300 km/h) and there were wind gusts to 220 m.p.h. (355 km/h).  The minimum surface pressure was 892 mb.

A Hurricane Warning is in effect for Jamaica.

Hurricane Warnings are in effect for the Cuban provinces of Granma, Santiago de Cuba, Guantanamo, and Holguin.

Hurricane Warnings are in effect for the Central Bahamas and the Southeastern Bahamas.

A Hurricane Watch is in effect for the Turks and Caicos.

A Tropical Storm Warning is in effect for Haiti.

A Tropical Storm Warning is in effect for the Cuban province of Las Tunas.

A Tropical Storm Warning is in effect for the Turks and Caicos.

Winds to tropical storm force were already occurring in Jamaica even though the core of Hurricane Melissa was still southwest of Jamaica.  A weather station at the Norman Manley International Airport in Kingston reported a sustained wind speed of 43 m.p.h. (69 km/h) and a wind gust of 59 m.p.h. (93 km/h).  A weather station at the Sangster International Airport in Montego Bay reported a sustained wind speed of 38 m.p.h. (61 km/h) and a wind gust of 54 m.p.h. (87 km/h).  Heavy rain was already falling over parts of Jamaica.

The core of dangerous Hurricane Melissa was nearing the coast of southwestern Jamaica on Tuesday morning.  A circular eye with a diameter of 12 miles (19 km) was at the center of Melissa’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Melissa.  Storms near the center of Melissa generated strong upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass in the upper levels was nearly balanced by a strong inflow of mass in the lower levels of the atmosphere.  The near balance of inflow and outflow of mass caused the surface pressure to remain nearly steady during the past few hours.

Winds to hurricane force extended out 30 miles (50 km) from the center of Hurricane Melissa.   Winds to tropical storm force extended out 195 miles (315 km) in the eastern half of Melissa’s circulation.  Winds to tropical storm force extended out 90 miles (145 km) in the western side of Hurricane Melissa.

The Hurricane Intensity Index (HII) for Hurricane Melissa is 44.1.  The Hurricane Size index (HSI) is 11.4 and the Hurricane Wind Intensity Size Index (HWISI) is 55.5.  Hurricane Melissa is similar in size and intensity to Hurricane Dorian when Dorian hit the Bahamas in 2019.

Hurricane Melissa will move through an environment favorable for a very powerful hurricane during the few hours until it makes landfall in Jamaica.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Melissa is likely to maintain its intensity until it makes landfall in Jamaica unless an eyewall replacement cycle occurs.  If the inner end of a rainband wraps around the existing eye and eyewall, then the formation of concentric eyewalls would cause Melissa to start to weaken.

An upper level trough over the southeastern U.S. will steer Hurricane Melissa toward the northeast during the next 24 hours.  On its anticipated track, the core of Hurricane Melissa will reach southwestern Jamaica on Tuesday morning.  Melissa will move northeast across Jamaica during much of Tuesday.  Hurricane Melissa will reach eastern Cuba early on Wednesday.

Hurricane Melissa will drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic.  Very heavy rain is likely to cause catastrophic floods in some locations.  Hurricane Melissa will also produce very strong winds in Jamaica.  Melissa will be capable of causing severe damage.  Widespread electricity outages are likely.  Infrastructure and transportation are likely to be severely damaged.  Melissa could produce a storm surge of up to 16 feet (5 meters) along the south coast of Jamaica.

Hurricane Melissa will also bring strong winds and locally heavy rain to eastern Cuba, the Central and Southeastern Bahamas, and the Turks and Caicos.  Heavy rain is likely to cause flash floods in some locations.  Widespread electricity outages are also likely in eastern Cuba.

Hurricane Melissa Turns Toward Jamaica

Hurricane Melissa started to make a slow turn toward Jamaica on Monday evening.  At 11:00 p.m. EDT on Monday the center of Hurricane Melissa was located at latitude 16.6°N and longitude 78.5°W which put the center about 150 miles (240 km) southwest of Kingston, Jamaica.  Melissa was moving toward the north-northeast at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 175 m.p.h. (285 km/h) and there were wind gusts to 205 m.p.h. (330 km/h).  The minimum surface pressure was 903 mb.

A Hurricane Warning is in effect for Jamaica.

Hurricane Warnings are in effect for the Cuban provinces of Granma, Santiago de Cuba, Guantanamo, and Holguin.

Hurricane Warnings are in effect for the Central Bahamas and the Southeastern Bahamas.

A Hurricane Watch is in effect for the Turks and Caicos.

A Tropical Storm Warning is in effect for Haiti.

A Tropical Storm Warning is in effect for the Cuban province of Las Tunas.

A Tropical Storm Warning is in effect for the Turks and Caicos.

Powerful Hurricane Melissa started a slow turn toward Jamaica on Monday evening.  A circular eye with a diameter of 12 miles (19 km) was at the center of Melissa’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Melissa.  Storms near the center of Melissa generated strong upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass in the upper levels was nearly balanced by a strong inflow of mass in the lower levels of the atmosphere.  The near balance of inflow and outflow of mass caused the surface pressure to remain nearly steady during the past few hours.

Winds to hurricane force extended out 30 miles (50 km) from the center of Melissa’s circulation.  Winds to tropical storm force extended out 195 miles (315 km) in the eastern half of Hurricane Melissa.  Winds to tropical storm force extended out 90 miles (145 km) in the western side of Melissa’s circulation.

The Hurricane Intensity Index (HII) for Hurricane Melissa is 40.4.  The Hurricane Size index (HSI) is 11.4 and the Hurricane Wind Intensity Size Index (HWISI) is 51.8.  Hurricane Melissa is similar in size and intensity to Hurricane Andrew when Andrew was at its peak intensity in 1992.

Hurricane Melissa will move through an environment favorable for a very powerful hurricane during the next 12 hours.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Melissa is likely to maintain its intensity during the next 12 hours unless an eyewall replacement cycle occurs.  If the inner end of a rainband wraps around the existing eye and eyewall, then the formation of concentric eyewalls would cause Melissa to weaken.

An upper level trough over the southeastern U.S. will start to steer Hurricane Melissa toward the northeast during the next 24 hours.  On its anticipated track, the core of Hurricane Melissa will reach southwestern Jamaica on Tuesday morning.  Melissa will move northeast across Jamaica during much of Tuesday.  Hurricane Melissa will reach eastern Cuba early on Wednesday.

Hurricane Melissa will drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic.  Very heavy rain is likely to cause catastrophic floods in some locations.  Hurricane Melissa will also produce very strong winds in Jamaica.  Melissa will be capable of causing severe damage.  Widespread electricity outages are likely.  Infrastructure and transportation are likely to be severely affected.  Melissa could produce a storm surge of up to 16 feet (5 meters) along the south coast of Jamaica.

Hurricane Melissa will also bring strong winds and locally heavy rain to eastern Cuba, the Central and Southeastern Bahamas, and the Turks and Caicos.  Heavy rain is likely to cause flash floods in some locations.  Widespread electricity outages are also likely in eastern Cuba.

Hurricane Melissa Intensifies to Cat. 5

Hurricane Melissa intensified to Category 5 on the Saffir-Simpson Scale early on Monday.  At 8:00 a.m. EDT on Monday the center of Hurricane Melissa was located at latitude 16.4°N and longitude 78.0°W which put the center about 135 miles (220 km) southwest of Kingston, Jamaica.  Melissa was moving toward the west at 3 m.p.h. (5 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 913 mb.

A Hurricane Warning is in effect for Jamaica.

Hurricane Warnings are in effect for the Cuban provinces of Granma, Santiago de Cuba, Guantanamo, and Holguin.

Hurricane Watches are in effect for the Central Bahamas, the Southeastern Bahamas, and the Turks and Caicos.

A Tropical Storm Warning is in effect for Haiti.

A Tropical Storm Warning is in effect for the Cuban province of Las Tunas.

Hurricane Melissa intensified to Category 5 on the Saffir-Simpson Scale early on Monday.  A circular eye with a diameter of 12 miles (19 km) was at the center of Melissa’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Melissa.  Storms near the center of Melissa generated strong upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

Winds to hurricane force extended out 30 miles (50 km) from the center of Melissa’s circulation.  Winds to tropical storm force extended out 195 miles (315 km) in the eastern half of Hurricane Melissa.  Winds to tropical storm force extended out 90 miles (145 km) in the western side of Melissa’s circulation.

The Hurricane Intensity Index (HII) for Hurricane Melissa is 35.0.  The Hurricane Size index (HSI) is 11.4 and the Hurricane Wind Intensity Size Index (HWISI) is 46.4.  Hurricane Melissa is similar in size and intensity to Hurricane Andrew when Andrew made landfall in South Florida in 1992.

Hurricane Melissa will move through an environment favorable for a very powerful hurricane during the next 24 hours.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Melissa could intensify during the next 24 hours unless an eyewall replacement cycle occur.  If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could cause Melissa to weaken.

The high pressure system that has been steering Hurricane Melissa slowly toward the west is likely to weaken during the next 24 hours.  When the high pressure system weakens, Melissa will start to move slowly toward the north.  On its anticipated track, the core of Hurricane Melissa will hit Jamaica early on Tuesday.

Hurricane Melissa will drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic.  Very heavy rain is likely to cause catastrophic floods in some locations.  Hurricane Melissa will also produce very strong winds in Jamaica.  Melissa will be capable of causing severe damage.  Widespread electricity outages are likely.  Melissa could produce a storm surge of up to 16 feet (5 meters) along the south coast of Jamaica.

Hurricane Melissa will also bring strong winds and locally heavy rain to eastern Cuba, the Central and Southeastern Bahamas, and the Turks and Caicos.

Tropical Cyclone Montha Forms over Bay of Bengal

Tropical Cyclone Montha formed over the Bay of Bengal on Sunday.  At 5:00 p.m. EDT on Sunday the center of Tropical Cyclone Montha was located at latitude 11.6°N and longitude 85.2°E which put the center about 380 miles (615 km) east-southeast of Chennai, India.  Montha was moving toward the west at 8 m.p.h. (13 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 998 mb.

A low pressure system over the Bay of Bengal strengthened on Sunday and the India Meteorological Department designated the system as Tropical Cyclone Montha.

The distribution of thunderstorms in Tropical Cyclone Montha was asymmetrical.  Thunderstorms were occurring in bands in the western side of Montha’s circulation.  The bands in the eastern side of Tropical Cyclone Montha consisted primarily of showers and lower clouds.  Storms near the center of Montha generated upper level divergence that pumped mass away to the west of the tropical cyclone.  The removal of mass caused the surface pressure to decrease.

The strongest winds were occurring in the southwestern part of Tropical Cyclone Montha.  Winds to tropical storm force extended out 85 miles (135 km) in the southwestern quadrant of Montha’s circulation.  The winds in the other parts of Tropical Cyclone Montha were blowing at less than tropical storm force.

Tropical Cyclone Montha will move through an environment somewhat favorable for intensification during the next 24 hours.  Montha will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern part of an upper level ridge that is over Southeast Asia.  The upper level ridge will produce easterly winds that will blow toward the top of Montha’s circulation.  Those winds will cause moderate vertical wind shear.  The moderate vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification.  Tropical Cyclone Montha could intensify a little during the next 24 hours.

Tropical Cyclone Montha will move around the western side of a high pressure system that is over Southeast Asia.  The high pressure system will steer Montha toward the northwest during the next 24 hours.  On its anticipated track, Tropical Cyclone Montha will move toward the east coast of India.

 

Tropical Storm Sonia Spins Southwest of Baja California

Tropical Storm Sonia continued to spin over the Eastern North Pacific Ocean southwest of Baja California on Sunday.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Sonia was located at latitude 13.7°N and longitude 119.9°W which put the center about 910 miles (1470 km) southwest of the southern tip of Baja California.  Sonia was moving toward the west at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1002 mb.

An upper level trough over the Eastern North Pacific Ocean was producing southerly winds that were blowing toward the top of Tropical Storm Sonia.  Those winds were causing moderate vertical wind shear.  The moderate vertical wind shear was causing the distribution of thunderstorms in Tropical Storm Sonia to be asymmetrical.  Thunderstorms were occurring in bands in the northern half of Sonia’s circulation.  Bands in the southern half of Tropical Storm Sonia consisted primarily of showers and lower clouds.

The circulation around Tropical Storm Sonia was small.  Winds to tropical storm force extended out 60 miles (95 km) from the center of Sonia’s circulation.

Tropical Storm Sonia will move through an environment that will be marginally favorable for intensification during the next 24 hours.  Sonia will move over water where the Sea Surface Temperatures are near 27°C.  However, the upper level trough over the Eastern North Pacific Ocean will continue to cause moderate vertical wind shear.  The vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification.  Tropical Storm Sonia could intensify a little during the next 24 hours.

Tropical Storm Sonia will move around the southern side of a high pressure system over the Eastern North Pacific Ocean.  The high pressure system will steer Sonia toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Sonia will remain far to the southwest of Baja California.

Hurricane Melissa Strengthens to Cat. 4

Hurricane Melissa strengthened to Category 4 on the Saffir-Simpson Scale south of Jamaica early on Sunday morning.  At 8:00 a.m. EDT on Sunday the center of Hurricane Melissa was located at latitude 16.3°N and longitude 76.4°W which put the center about 120 miles (195 km) south-southeast of Kingston, Jamaica.  Melissa was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 952 mb.

A Hurricane Warning is in effect for Jamaica.

A Hurricane Watch is in effect for the Cuban provinces of Granma, Santiago de Cuba, Guantanamo, and Holguin.

A Hurricane Watch is in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

A Tropical Storm Warning is also in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

Hurricane Melissa strengthened to Category 4 on the Saffir-Simpson Scale early on Sunday morning.  A circular eye with a diameter of 20 miles (32 km) was at the center of Melissa’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Melissa.  Storms near the center of Melissa generated upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Hurricane Melissa was relatively small.  Winds to hurricane force extended out 25 miles (40 km) from the center of Melissa’s circulation.  Winds to tropical storm force extended out 170 miles (280 km) in the eastern half of Hurricane Melissa.  Winds to tropical storm force extended out 90 miles (145 km) in the western side of Melissa’s circulation.

The Hurricane Intensity Index (HII) for Hurricane Melissa is 28.3.  The Hurricane Size index (HSI) is 9.3 and the Hurricane Wind Intensity Size Index (HWISI) is 37.6.  Hurricane Melissa is similar in size and intensity to Hurricane Charley when Charley made landfall in Southwest Florida in 2004.

Hurricane Melissa will move through an environment that will be favorable for intensification during the next 24 hours.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Melissa will intensify during the next 24 hours. Melissa could intensify rapidly at times.  Melissa could strengthen to category 5 on the Saffir-Simpson Scale.

Hurricane Melissa will move around the southern side of a high pressure system that is north of Cuba.  The high pressure system will steer Melissa slowly toward the west during the next 24 hours.  On its anticipated track, Hurricane Melissa will move slowly south of Jamaica on Sunday.  The high pressure system will weaken on Monday and Melissa will move toward Jamaica

Hurricane Melissa is likely to drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic.  Very heavy rain is likely to cause catastrophic floods in some locations.  Hurricane Melissa will also produce very strong winds in Jamaica.  Melissa will be capable of causing severe damage.  Widespread electricity outages are likely.  Melissa could produce a storm surge of up to 16 feet (5 meters) along the south coast of Jamaica.

Hurricane Melissa will also bring strong winds and locally heavy rain to eastern Cuba early next week.

Melissa Rapidly Intensifies to a Major Hurricane

Hurricane Melissa rapidly intensified to a major hurricane southeast of Jamaica on Saturday evening.  At 11:00 p.m. EDT on Saturday the center of Hurricane Melissa was located at latitude 16.4°N and longitude 75.9°W which put the center about 115 miles (185 km) south-southeast of Kingston, Jamaica.  Melissa was moving toward the west at 3 m.p.h. (5 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. (215 km/h).  The minimum surface pressure was 967 mb.

A Hurricane Warning is in effect for Jamaica.

A Hurricane Watch is in effect for the Cuban provinces of Granma, Santiago de Cuba, Guantanamo, and Holguin.

A Hurricane Watch is in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

A Tropical Storm Warning is also in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

Hurricane Melissa rapidly intensified to a major hurricane on Saturday evening.  A circular eye with a diameter of 20 miles (32 km) was at the center of Melissa’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Melissa.  Storms near the center of Melissa generated upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The size of the circulation around Hurricane Melissa increased on Saturday.  Winds to hurricane force extended out 25 miles (40 km) from the center of Melissa’s circulation.  Winds to tropical storm force extended out 160 miles (260 km) in the eastern half of Hurricane Melissa.  Winds to tropical storm force extended out 90 miles (145 km) in the western side of Melissa’s circulation.

The Hurricane Intensity Index (HII) for Hurricane Melissa is 20.6.  The Hurricane Size index (HSI) is 9.3 and the Hurricane Wind Intensity Size Index (HWISI) is 29.9.

Hurricane Melissa will move through an environment that will be favorable for intensification during the next 24 hours.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Melissa will intensify during the next 24 hours.  Melissa is likely to continue to intensify rapidly during the next few hours.  Melissa could strengthen to category 5 on the Saffir-Simpson Scale.

Hurricane Melissa will move around the southern side of a high pressure system that is north of Cuba.  The high pressure system will steer Melissa slowly toward the west during the next 24 hours.  On its anticipated track, Hurricane Melissa will move slowly south of Jamaica on Sunday.  The high pressure system will weaken on Monday and Melissa will move toward Jamaica

Hurricane Melissa is likely to drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic. Very heavy rain is likely to cause catastrophic floods in some locations.  Hurricane Melissa will also produce very strong winds in Jamaica.  Widespread electricity outages are likely.  Melissa could produce a storm surge of up to 16 feet (5 meters) along the south coast of Jamaica.

Hurricane Melissa will also bring strong winds and locally heavy rain to eastern Cuba early next week.

Melissa Strengthens to a Hurricane

Former Tropical Storm Melissa strengthened to a hurricane southeast of Jamaica on Saturday afternoon.  At 2:00 p.m. EDT on Saturday the center of Hurricane Melissa was located at latitude 16.6°N and longitude 75.2°W which put the center about 145 miles (230 km) southeast of Kingston, Jamaica.  Melissa was moving toward the west-northwest at 1 m.p.h. (2 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 980 mb.

A Hurricane Warning is in effect for Jamaica.

A Hurricane Watch is in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

A Tropical Storm Warning is also in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

Former Tropical Storm Melissa strengthened to a hurricane over the Caribbean Sea southeast of Jamaica on Saturday afternoon.  A circular eye with a diameter of 23 miles (37 km) formed at the center of Melissa’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Melissa.  Storms near the center of Melissa generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The size of the circulation around Hurricane Melissa increased on Saturday.  Winds to hurricane force extended out 35 miles (55 km) from the center of Melissa’s circulation.  Winds to tropical storm force extended out 125 miles (200 km) in the eastern half of Hurricane Melissa.  Winds to tropical storm force extended out 70 miles (110 km) in the western side of Melissa’s circulation.

Hurricane Melissa will move through an environment that will be favorable for intensification during the next 24 hours.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the southwestern part of an upper level trough that is north of Hispaniola.  The upper level trough will produce northerly winds that will blow toward the top of Melissa’s circulation.  Those winds will produce some vertical wind shear, but the winds will get weaker during the next 24 hours.  The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Hurricane Melissa will intensify during the next 24 hours.  Melissa is likely to intensify rapidly at times.  Melissa is likely to strengthen to a major hurricane on Sunday.

Hurricane Melissa will move around the western end of a high pressure system that is over the Atlantic Ocean.  The high pressure system will steer Melissa slowly toward the northwest during the next 24 hours.  On its anticipated track, Hurricane Melissa will move slowly toward Jamaica.

Hurricane Melissa is likely to drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic.  Very heavy rain is likely to cause catastrophic floods in some locations.

 

Tropical Storm Sonia Forms Southwest of Baja California

Tropical Storm Sonia formed over the Eastern North Pacific Ocean southwest of Baja California early on Saturday.  At 5:00 a.m. EDT on Saturday the center of Tropical Storm Sonia was located at latitude 13.3°N and longitude 117.6°W which put the center about 835 miles (1340 km) southwest of the southern tip of Baja California.  Sonia was moving toward the west 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 1006 mb.

A low pressure system over the Eastern North Pacific Ocean southwest of Baja California strengthened early on Saturday and the U.S. National Hurricane Center designated the system as Tropical Storm Sonia.

More thunderstorms developed near the center of Tropical Storm Sonia early on Saturday.  Thunderstorms also were forming in bands revolving around the center of Sonia’s circulation.  Storms near the center of Sonia started to generate upper level divergence that pumped mass away from the tropical storm.

The circulation around Tropical Storm Sonia was small.  Winds to tropical storm force extended out 60 miles (95 km) in the northern half of Sonia’s circulation.  Winds to tropical storm force extended out 25 miles (40 km) in the southern side of Tropical Storm Sonia.

Tropical Cyclone Sonia will move through an environment that is favorable for intensification during the next 24 hours.  Sonia will move over water where the Sea Surface Temperatures are near 27°C.  It will move under the eastern side of an upper level trough that is over the Eastern North Pacific Ocean.  The upper level trough will produce southwesterly winds that will blow toward the top of Sonia’s circulation.  Those winds will cause some vertical wind shear.  The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Tropical Storm Sonia will intensify during the next 24 hours.

Tropical Storm Sonia will move around the southern side of a high pressure system over the Eastern North Pacific Ocean.  The high pressure system will steer Sonia toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Sonia will move farther away from Baja California.

Tropical Storm Melissa Strengthens

Tropical Storm Melissa started to strengthen on Friday afternoon as it meandered over the Caribbean Sea southeast of Jamaica.  At 12:30 p.m. EDT on Friday the center of Tropical Storm Melissa was located at latitude 15.6°N and longitude 74.5°W which put the center about 220 miles (355 km) southeast of Kingston, Jamaica.  Melissa was moving toward the east-southeast at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 999 mb.

A Hurricane Watch is in effect for Jamaica.

A Hurricane Watch is also in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

A Tropical Storm Warning is in effect for Jamaica.

A Tropical Storm Warning is in effect for the southern coast of Haiti from the border with the Dominican Republic to Port Au Prince.

A U.S. Air Force Reserve Hurricane Hunter aircraft determined that Tropical Storm Melissa had started to strengthen early on Friday afternoon.  The reconnaissance plane found stronger winds and a decreasing surface pressure in Tropical Storm Melissa.

Tropical Storm Melissa also looked like a stronger tropical storm on satellite images.  Stronger thunderstorms developed near the center of Melissa’s circulation.  Stronger thunderstorms also formed in bands in the eastern side of Tropical Storm Melissa.  Bands in the western side of Melissa’s circulation still consisted primarily of showers and lower clouds.  Storms near the center of Melissa generated more upper level divergence that pumped mass away to the east of the tropical storm.  The removal of mass caused the surface pressure to decrease.

Even though Tropical Storm Melissa started to strengthen on Friday afternoon, the strongest winds were still occurring in the eastern side of Melissa’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) in the eastern half of Tropical Storm Melissa.  The winds in the western half of Melissa’s circulation were blowing at less than tropical storm force.

Tropical Storm Melissa will move through an environment that will be favorable for intensification during the next 24 hours.  Melissa will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the south part of an upper level trough that is north of Hispaniola.  The upper level trough will produce southwesterly winds that will blow toward the top of Melissa’s circulation.  Those winds will produce some vertical wind shear, but the winds will get weaker during the next 24 hours.  The vertical wind shear will inhibit intensification, but the wind shear will not be enough to prevent intensification.  Tropical Storm Melissa will intensify during the next 24 hours.  Melissa could intensify rapidly at times.  Tropical Storm Melissa is likely to strengthen to a hurricane by Saturday afternoon.  Melissa could intensify to a major hurricane by Sunday.

Tropical Storm Melissa will move around the western end of a high pressure system that is over the Atlantic Ocean.  The high pressure system will steer Melissa slowly toward the north-northwest during the next 24 hours. On its anticipated track, Tropical Storm Melissa will move slowly toward Jamaica.

Tropical Storm Melissa is likely to drop very heavy rain on Jamaica, Haiti and parts of the Dominican Republic.  Very heavy rain is likely to cause catastrophic floods in some locations.